U.S. patent application number 10/352865 was filed with the patent office on 2003-07-24 for satellite broadcasting system.
Invention is credited to Fujimori, Yukiyoshi, Kikuchi, Hideo, Koishi, Yoichi, Oka, Masaru, Suenaga, Masashi.
Application Number | 20030137963 10/352865 |
Document ID | / |
Family ID | 27553481 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030137963 |
Kind Code |
A1 |
Suenaga, Masashi ; et
al. |
July 24, 2003 |
Satellite broadcasting system
Abstract
In a broadcasting receiver, to quickly switch channels of the
received multiplexed broadcasting signals at a high response speed
to improve the convenience for a viewer, when broadcasting signals
of a plurality of channels are to be code-division-multiplexed and
broadcasted from a ground broadcasting station (BC1, BC2) to a
broadcasting receiver (MS) in a service area via a geostationary
satellite (SAT), the broadcasting signals are multiplexed and
transmitted after matching the spreading code phase between the
channels in the ground broadcasting station (BC1, BC2).
Alternatively, the spreading code phase difference between the
channels of a CDM broadcasting signal arriving from the ground
broadcasting station (BC1, BC2) is detected in the geostationary
satellite (SAT), and the broadcasting signal is transmitted to the
broadcasting receiver (MS) after matching the spreading code phase
between the channels on the basis of the detection result.
Inventors: |
Suenaga, Masashi;
(Zushi-shi, JP) ; Oka, Masaru; (Yokohama-shi,
JP) ; Koishi, Yoichi; (Ota-ku, JP) ; Fujimori,
Yukiyoshi; (Yokohama-shi, JP) ; Kikuchi, Hideo;
(Kawaguchi-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
27553481 |
Appl. No.: |
10/352865 |
Filed: |
January 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10352865 |
Jan 29, 2003 |
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09147763 |
Mar 3, 1999 |
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09147763 |
Mar 3, 1999 |
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PCT/JP98/03020 |
Jul 3, 1998 |
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Current U.S.
Class: |
370/342 ;
370/320 |
Current CPC
Class: |
H04B 7/18526
20130101 |
Class at
Publication: |
370/342 ;
370/320 |
International
Class: |
H04B 007/216 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 3, 1997 |
JP |
9-178659 |
Jul 3, 1997 |
JP |
9-178674 |
Jul 3, 1997 |
JP |
9-178676 |
Jul 3, 1997 |
JP |
9-178677 |
Jul 3, 1997 |
JP |
9-178678 |
Jul 3, 1997 |
JP |
9-178679 |
Claims
1. A radio receiver (MS) carried by a mobile (MS) and used in a
radio communication system for radio-transmitting a transmission
signal modulated by a predetermined modulation scheme for multipath
transmission for which both a direct wave and an indirect wave are
used, said apparatus (MS) comprising: signal synthesis means (213)
for synthesizing signals obtained by a plurality of antennas (211,
212) spaced apart from each other; and reception means (214) for
receiving a synthesis signal obtained by said signal synthesis
means and performing predetermined multipath reception
processing.
2. A radio receiver according to claim 1, wherein two of the
plurality of antennas (211, 212) are arranged on the mobile while
being offset from each other both in a moving direction of the
mobile carrying the antennas and in a direction perpendicular to
the moving direction.
3. A radio receiver according to claim 1, wherein two antennas
(211, 212) provided on the mobile while being offset from each
other both in a moving direction of the mobile carrying the
antennas and in a direction perpendicular to the moving direction
are respectively arranged near two points on a contour of the
mobile where a linear distance between the two antennas is
maximized.
4. A radio receiver (MS) used in a radio communication system for
radio-transmitting a predetermined transmission signal and carried
by a mobile (MS), said apparatus (MS) comprising: reception means
(214) for demodulating transmission data from the radio-transmitted
transmission signal; storage means (225) for storing the
transmission data obtained by said reception means at least for a
predetermined period; hit detection means (226) for detecting a hit
generated in the transmission signal received by said reception
means; and compensation means (227) for compensating transmission
data corresponding to a transmission signal portion where the hit
is detected by said hit detection means, on the basis of the
transmission data stored in said storage means.
5. A radio broadcasting system for radio-broadcasting a
predetermined transmission signal from a radio broadcasting
apparatus (BC1, BC2) to a radio receiver (MS), said system
comprising: reception means (228), arranged in the radio receiver,
for demodulating transmission data from the radio-broadcasted
transmission signal; delay means (229), arranged in the radio
receiver, for delaying the transmission data obtained by said
reception means at least for a predetermined period; hit detection
means (231), arranged in the radio receiver, for detecting a hit
generated in-the transmission signal received by said reception
means; retransmission request means (232), arranged in the radio
receiver, for requesting the radio broadcasting apparatus to
retransmit a transmission signal corresponding to a portion where
the hit is detected by said hit detection means; retransmission
means (237), arranged in the radio broadcasting apparatus, for
transmitting the transmission signal corresponding to the requested
portion using a predetermined retransmission channel in response to
the retransmission request from said retransmission request means;
and compensation means (230), arranged in the radio receiver, for
compensating, in the transmission data delayed by said delay means,
transmission data corresponding to the transmission signal portion
where the hit is detected by said hit detection means, using
transmission data demodulated, by said reception means, from the
transmission signal transmitted from said retransmission means in
response to the request from said retransmission request means and
arriving through the retransmission channel.
6. A radio receiver (MS) carried by a mobile (MS) and used in a
radio broadcasting system for radio-broadcasting a predetermined
transmission signal from a radio broadcasting apparatus (BC1, BC2)
to the radio receiver (MS), said apparatus.(MS) comprising:
reception means (228) for demodulating transmission data from the
radio-broadcasted transmission signal; delay means (229) for
delaying the transmission data obtained by said reception means at
least for a predetermined period; hit detection means (231) for
detecting a hit generated in the transmission signal received by
said reception means; retransmission request means (232) for
requesting the radio broadcasting apparatus to retransmit a
transmission signal corresponding to a portion where the hit is
detected by said hit detection means; and compensation means (230)
for compensating, in the transmission data delayed by said delay
means, transmission data corresponding to the transmission signal
portion where the hit is detected by said hit detection means,
using transmission data demodulated, by said reception means, from
the transmission signal transmitted from the radio broadcasting
apparatus in response to the request from said retransmission
request means and arriving through a predetermined retransmission
channel.
7. A radio broadcasting apparatus (BC1, BC2) used in a radio
broadcasting system for radio-broadcasting a predetermined
transmission signal from the radio broadcasting apparatus (BC1,
BC2) to a radio receiver (MS), said apparatus (BC1, BC2)
comprising: means (240) for receiving a retransmission request from
the radio receiver; and retransmission means (237) for transmitting
a transmission signal of a requested portion using a predetermined
retransmission channel in response to the request.
Description
TECHNICAL FIELD
[0001] The present invention relates to a satellite broadcasting
system for broadcasting information such as video, audio, and data
to a specific ground service area using a broadcasting satellite or
a communication satellite on the geostationary orbit and, more
particularly, to a system for multiplexing and broadcasting a
plurality of channels by code division multiplex (CDM: Code
Division Multiplex).
BACKGROUND ART
[0002] In recent years, various communication systems have been
developed along with an increase in requirements for communications
and progress in communication technologies. One of such
communication systems is a satellite broadcasting system using a
broadcasting satellite or a communication satellite on the
geostationary orbit. The satellite broadcasting system has an
advantage that it can provide an information broadcasting service
to a wide service area without any large-scale infrastructure on
the ground.
[0003] A satellite broadcasting system in operation to date is an
analog system which multiplexes a plurality of channels by
frequency division multiplex (FDM: Frequency Division Multiplex).
In a system of this type, however, the degree of channel multiplex
per frequency is low, so this system cannot meet a requirement for
more channels, which has arisen along with recent advances in
multimedia technologies.
[0004] Recently, digital satellite broadcasting systems have been
extensively studied and developed. In this case, use of, e.g.,
orthogonal frequency division multiplex (OFDM: Orthogonal Frequency
Division Multiplex) or code division multiplex (CDM: Code Division
Multiplex) has been examined as channel multiplex schema.
[0005] However, these multiplex schema have various problems to be
solved before they are applied to the satellite broadcasting
system. Especially, CDM requires a time as long as, e.g., ten-odd
seconds until the receiver establishes spreading code
synchronization for a broadcasting signal. For this reason, the
receiver needs a long time from the start to completion of channel
switching. The viewers must wait for a long time every time the
channel is switched and feel displeased. In some cases, important
information may be lost during the channel switching period, and a
measure is necessary.
[0006] Considering the above problems, a demand has arisen for a
satellite broadcasting system which allows the broadcasting
receiver to quickly switch the channels for the received
multiplexed broadcasting signals at a high response speed, thereby
improving the convenience for the viewers.
[0007] In Japan, satellite broadcasting systems using a BS
(Broadcasting Satellite) and a CS (Communication Satellite) have
already been put into practice, and digital broadcasting has also
been started. In other countries as well, satellite broadcasting
systems of almost the same scale have been developed and put into
practice.
[0008] However, these satellite broadcasting systems require use of
a parabolic antenna having a diameter of about 40 to 50 cm or a
planar array antenna almost equal in size as a reception antenna.
In addition, unless the antenna is precisely directed to the
satellite, no sufficient gain is obtained, and reception is
disabled.
[0009] These systems assume indoor reception/viewing, so it is hard
to provide a satellite broadcasting receiver using a simple antenna
system meeting requirements for use on a mobile or use as a
portable device. An apparatus meeting these requirements can
effectively function as a means for providing urgent information in
disasters or the like and its implementation in the near future is
awaited.
[0010] Various types of satellite broadcasting systems, receivable
by a receiver using a simple antenna system, or satellite
broadcasting receivers have been proposed to cope with the
requirements. However, since these systems or apparatuses use a
very high frequency in, e.g., the S band, and radio waves have high
linear propagation properties, the radio waves maybe shielded by a
small obstacle such as an electrical wire in an extreme case.
Generally, when the reception terminal is moving, small obstacles
frequently enter between the broadcasting satellite and the
reception terminal. This repeatedly generates hits and largely
influences the reception quality.
[0011] From this viewpoint, a demand has arisen for a radio
receiver, a radio broadcasting system, and a radio broadcasting
apparatus capable of minimizing the influence of hits due to
obstacles and obtaining a satisfactory reception quality.
[0012] A direct wave from the satellite cannot be received in an
area behind buildings. To solve this problem, conventionally, a
public antenna having a large diameter is arranged on the rooftop
of a high-rise building or a pylon. The radio signal from the
satellite is received and amplified by this public antenna. This
received radio signal is distributed to the receivers of users
behind buildings through coaxial cables or optical cables. With
this arrangement, users behind buildings, who cannot receive the
radio signal from the satellite, can also completely receive
transmission information from the satellite.
[0013] However, such a public reception system requires large-scale
construction and enormous cost because cables must be laid to all
users. Recently, information transmission using the satellite
broadcasting system not only to fixed stations but also to mobile
stations has been proposed. In this case, users as fixed stations
behind buildings can receive information from the satellite through
the above-described public reception system. However, mobile
stations behind the buildings cannot receive information from the
satellite because no coaxial cables or optical cables can be laid
to the mobile stations.
[0014] Under the circumstance, a demand has arisen for a satellite
broadcasting system capable of making not only a fixed station but
also a mobile station in an area behind buildings, where a radio
signal from the satellite cannot be directly received, properly
receive the radio signal without preparing large-scale equipment,
thereby realizing an inexpensive and effective gap filler, and a
gap filler apparatus therefor.
[0015] In satellite broadcasting systems of any types, when the
number of broadcasting channels is increased, the output
requirement for a repeater-side power amplifier on the satellite
becomes high accordingly, so it is difficult to require an increase
in number of broadcasting channels.
[0016] In view of the foregoing, a demand has arisen for a
satellite broadcasting system and a reception terminal, which can
easily increase the number of channels with a simple
arrangement.
[0017] The satellite broadcasting systems require use of a
parabolic antenna having a diameter of about 40 to 50 cm or a
planar array antenna almost equal in size as a reception antenna.
In addition, unless the antenna is precisely directed to the
satellite, no sufficient gain is obtained, and reception is
disabled. These systems assume indoor reception/viewing, so it is
hard to provide a satellite broadcasting receiver using a simple
antenna system meeting requirements for use on a mobile or use as a
portable device. An apparatus meeting these requirements can
effectively function as a means for providing urgent information in
disasters or the like and its implementation in the near future is
awaited.
[0018] Under the circumstance, a demand has arisen for a satellite
broadcasting system, receivable by a receiver using a simple
antenna system meeting requirements for use on a mobile or use as a
portable device, and a satellite broadcasting receiver.
[0019] Development of a satellite broadcasting receiver for
receiving the above-described satellite broadcasting on a mobile
such as an automobile is prevalent recently.
[0020] To receive the satellite broadcasting on a mobile such as an
automobile, the driver must switch the reception channel in a
number of channels, as described above. Since this channel
selection operation is cumbersome and distracts the driver from
driving, a traffic accident may be caused.
[0021] To prevent this danger, various danger prevention methods
have been proposed conventionally but any conclusive methods has
not appeared. Therefore, a demand has arisen for a satellite
broadcasting receiver capable of switching the reception channel
without distracting the driver from driving.
[0022] Music for stimulating the driver sometimes contributes to
prevent driving asleep. However, depending on the degree of fatigue
of the driver, monotonous music may make the driver sleep,
resulting in an adverse effect. This applies not only to the
drivers of automobiles but also to operators steering various
mobiles.
[0023] From this viewpoint, a demand has arisen for a satellite
broadcasting receiver capable of switching the reception channel
without distracting the driver of a mobile from driving. Also, a
demand has arisen for a satellite broadcasting receiver capable of
controlling reception channel switching in accordance with the
fatigue state of the driver to prevent a traffic accident.
[0024] Accordingly, it is an object of the present invention to
provide a satellite broadcasting system allowing a broadcasting
receiver to quickly switch the channels of received multiplexed
broadcasting signals at a high response speed, thereby improving
the convenience for a viewer.
[0025] It is another object of the present invention to provide a
radio receiver, a radio broadcasting system, and a radio
broadcasting apparatus capable of minimizing the influence of hits
due to obstacles and obtaining a satisfactory reception
quality.
[0026] It is still another object of the present invention to
provide a satellite broadcasting system capable of making not only
a fixed station but also a mobile station in an area behind
buildings, where a radio signal from the satellite cannot be
directly received, properly receive the radio signal without
preparing large-scale equipment, thereby realizing an inexpensive
and effective gap filler, and a gap filler apparatus therefor.
[0027] It is still another object of the present invention to
provide a satellite broadcasting system and a reception terminal,
which can easily increase the number of channels with a simple
arrangement.
[0028] It is still another object of the present invention to
provide a satellite broadcasting system capable of receiving a
signal by a receiver using a simple antenna system meeting
requirements for not only indoor use but also use on a mobile or
use as a portable device, and a satellite broadcasting
receiver.
[0029] It is still another object of the present invention to
provide a satellite broadcasting receiver capable of switching the
reception channel without distracting the driver of a mobile from
driving. It is still another object of the present invention to
provide a satellite broadcasting receiver capable of controlling
reception channel switching in accordance with the fatigue state of
the driver to prevent a traffic accident.
DISCLOSURE OF INVENTION
[0030] According to an aspect of the present invention, there is
provided a satellite broadcasting system for transmitting a
plurality of broadcasting signals of a plurality of channels from a
ground broadcasting station, repeating the broadcasting signals
with a geostationary satellite, and broadcasting the broadcasting
signals to a broadcasting receiver in a predetermined service area
on the ground, the ground broadcasting station comprising multiplex
means for spreading spectra of the broadcasting signals using
different spreading codes in units of channels and synthesizing the
broadcasting channels to code-division-multiplex the broadcasting
signals of the plurality of channels, and transmitting the
broadcasting signals, and transmission synchronization means for
setting a phase relationship of the spreading codes between the
broadcasting signals of the channels code-division-multiplexed by
the multiplex means in a predetermined synchronization state.
[0031] According to another aspect of the present invention, there
is provided a satellite broadcasting system for transmitting a
plurality of broadcasting signals of a plurality of channels from a
ground broadcasting station, repeating the broadcasting signals
with a geostationary satellite, and broadcasting the broadcasting
signals to a broadcasting receiver in a predetermined service area
on the ground, the ground broadcasting station comprising multiplex
means for spreading spectra of the broadcasting signals using
different spreading codes in units of channels and synthesizing the
broadcasting channels to code-division-multiplex the broadcasting
signals of the plurality of channels, and transmitting the
broadcasting signals, and the geostationary satellite comprising
phase difference detection means for receiving the
code-division-multiplexed broadcasting signals transmitted from the
ground broadcasting station and detecting a phase difference of the
spreading codes between the channels of the
code-division-multiplexed broadcasting signals, and transmission
synchronization means for setting a phase relationship of the
spreading codes between the channels of the received
code-division-multiplexed broadcasting signals in a predetermined
synchronization state on the basis of a detection result from the
phase difference detection means and transmitting the broadcasting
signals to the predetermined service area.
[0032] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for transmitting
a plurality of broadcasting signals of a plurality of channels from
a ground broadcasting station, repeating the broadcasting signals
with a geostationary satellite, and broadcasting the broadcasting
signals to a broadcasting receiver in a predetermined service area
on the ground, the ground broadcasting station comprising multiplex
means for spreading spectra of the broadcasting signals using
different spreading codes in units of channels and synthesizing the
broadcasting channels to code-division-multiplex the broadcasting
signals of the plurality of channels, and transmitting the
broadcasting signals, and phase difference information transmission
means for transmitting information representing a phase difference
of the spreading codes between the broadcasting signals of the
channels, which are multiplexed by the multiplex means, to notify
the geostationary satellite of the information, and the
geostationary satellite comprising phase difference information
reception means for receiving the information representing the
phase difference, and transmission synchronization means for
setting a phase relationship of the spreading codes between the
channels of the received code-division-multiplexed broadcasting
signals in a predetermined synchronization state on the basis of
the information representing the phase difference, which is
received by the phase difference information reception means, and
transmitting the broadcasting signals to the predetermined service
area.
[0033] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for transmitting
a plurality of broadcasting signals of a plurality of channels from
a ground broadcasting station, repeating the broadcasting signals
with a geostationary satellite, and broadcasting the broadcasting
signals to a broadcasting receiver in a predetermined service area
on the ground, the ground broadcasting station comprising multiplex
means for spreading spectra of the broadcasting signals using
different spreading codes in units of channels and synthesizing the
broadcasting channels to code-division-multiplex the broadcasting
signals of the plurality of channels, and transmitting the
broadcasting signals, and phase difference information transmission
means for transmitting information representing a phase difference
of the spreading codes between the broadcasting signals of the
channels, which are multiplexed by the multiplex means, to notify
the broadcasting receiver of the information, and the broadcasting
receiver comprising phase difference information reception means
for receiving the information representing the phase difference,
and reception synchronization means for establishing spreading code
synchronization for the channels of the code-division-multiplexed
broadcasting signals received via the geostationary satellite, on
the basis of the information representing the phase difference,
which is received by the phase difference information reception
means.
[0034] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for transmitting
a plurality of broadcasting signals of a plurality of channels from
a ground broadcasting station, repeating the broadcasting signals
with a geostationary satellite, and broadcasting the broadcasting
signals to a broadcasting receiver in a predetermined service area
on the ground, the ground broadcasting station comprising multiplex
means for spreading spectra of the broadcasting signals using
different spreading codes in units of channels and synthesizing the
broadcasting channels to code-division-multiplex the broadcasting
signals of the plurality of channels, and transmitting the
broadcasting signals, the geostationary satellite comprising phase
difference detection means for receiving the
code-division-multiplexed broadcasting signals transmitted from the
ground broadcasting station and detecting a phase difference of the
spreading codes between the channels of the
code-division-multiplexed broadcasting signals, and phase
difference information transmission means for transmitting
information representing the phase difference of the spreading
codes between the broadcasting signals of the channels, which is
detected by the phase difference detection means, to notify the
broadcasting receiver of the information, and the broadcasting
receiver comprising phase difference information reception means
for receiving the information representing the phase difference,
and reception synchronization means for establishing spreading code
synchronization for the channels of the code-division-multiplexed
broadcasting signals received via the geostationary satellite, on
the basis of the information representing the phase difference,
which is received by the phase difference information reception
means.
[0035] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for transmitting
a broadcasting signal of at least one channel from each of a
plurality of ground broadcasting stations, repeating the
broadcasting signals with a geostationary satellite, and
broadcasting the broadcasting signals to a broadcasting receiver in
a predetermined service area on the ground, each of the plurality
of ground broadcasting stations comprising transmission means for
spreading spectra of broadcasting signals to be transmitted from a
self station using different spreading codes in units of channels
and transmitting the broadcasting signals, and the geostationary
satellite comprising phase difference detection means for receiving
the broadcasting signals of the channels, which are transmitted
from the plurality of ground broadcasting stations, and detecting a
phase difference of the spreading codes between the broadcasting
signals of the channels, and repeat transmission synchronization
means for setting a phase relationship of the spreading codes
between the channels of the broadcasting signals received from the
plurality of ground broadcasting stations in a predetermined
synchronization state on the basis of a detection result from the
phase difference detection means and transmitting the broadcasting
signals to the predetermined service area. There is also provided a
satellite broadcasting system for transmitting a broadcasting
signal of at least one channel from each of a plurality of ground
broadcasting stations, repeating the broadcasting signals with a
geostationary satellite, and broadcasting the broadcasting signals
to a broadcasting receiver in a predetermined service area on the
ground, each of the plurality of ground broadcasting stations
comprising transmission means for spreading spectra of broadcasting
signals-to be transmitted from a self station using different
spreading codes in units of channels and transmitting the
broadcasting signals, and transmission timing control means for
variably controlling a transmission timing of the broadcasting
signals to be transmitted by the transmission means in units of
channels, and the geostationary satellite comprising phase
difference detection means for receiving the broadcasting signals
of the channels, which are transmitted from the plurality of ground
broadcasting stations, and detecting a phase difference of the
spreading codes between the broadcasting signals of the channels,
and phase difference information notification means for supplying
information representing the phase difference detected by the phase
difference detection means to each of the ground broadcasting
stations as sources, thereby causing the transmission timing
control means to variably control the transmission timing such that
the phase difference of the spreading codes between the
broadcasting signals of the channels transmitted from the ground
broadcasting stations is made zero.
[0036] According to still another aspect of the present invention,
there is provided a radio receiver carried by a mobile and used in
a radio communication system for radio-transmitting a transmission
signal modulated by a predetermined modulation scheme for multipath
transmission for which both a direct wave and an indirect wave are
used, comprising signal synthesis means for synthesizing signals
obtained by a plurality of antennas spaced apart from each other,
and reception means for receiving a synthesis signal obtained by
the signal synthesis means and performing predetermined multipath
reception processing. There is also provided a radio receiver used
in a radio communication system for radio-transmitting a
predetermined transmission signal and carried by a mobile,
comprising reception means for demodulating transmission data from
the radio-transmitted transmission signal, storage means for
storing the transmission data obtained by the reception means at
least for a predetermined period, hit detection means for detecting
a hit generated in the transmission signal received by the
reception means, and compensation means for compensating
transmission data corresponding to a transmission signal portion
where the hit is detected by the hit detection means, on the basis
of the transmission data stored in the storage means.
[0037] According to still another aspect of the present invention,
there is provided a radio broadcasting system for
radio-broadcasting a predetermined transmission signal from a radio
broadcasting apparatus to a radio receiver, comprising reception
means, arranged in the radio receiver, for demodulating
transmission data from the radio-broadcasted transmission signal,
delay means, arranged in the radio receiver, for delaying the
transmission data obtained by the reception means at least for a
predetermined period, hit detection means, arranged in the radio
receiver, for detecting a hit generated in the transmission signal
received by the reception means, retransmission request means,
arranged in the radio receiver, for requesting the radio
broadcasting apparatus to retransmit a transmission signal
corresponding to a portion where the hit is detected by the hit
detection means, retransmission means, arranged in the radio
broadcasting apparatus, for transmitting the transmission signal
corresponding to the requested portion using a predetermined
retransmission channel in response to the retransmission request
from the retransmission request means, and compensation means,
arranged in the radio receiver, for compensating, in the
transmission data delayed by the delay means, transmission data
corresponding to the transmission signal portion where the hit is
detected by the hit detection means, using transmission data
demodulated, by the reception means, from the transmission signal
transmitted from the retransmission means in response to the
request from the retransmission request means and arriving through
the retransmission channel.
[0038] According to still another aspect of the present invention,
there is provided a radio receiver carried by a mobile and used in
a radio broadcasting system for radio-broadcasting a predetermined
transmission signal from a radio broadcasting apparatus to the
radio receiver, comprising reception means for demodulating
transmission data from the radio-broadcasted transmission signal,
delay means for delaying the transmission data obtained by the
reception means at least for a predetermined period, hit detection
means for detecting a hit generated in the transmission signal
received by the reception means, retransmission request means for
requesting the radio broadcasting apparatus to retransmit a
transmission signal corresponding to a portion where the hit is
detected by the hit detection means, and compensation means for
compensating, in the transmission data delayed by the delay means,
transmission data corresponding to the transmission signal portion
where the hit is detected by the hit detection means, using
transmission data demodulated, by the reception means, from the
transmission signal transmitted from the radio broadcasting
apparatus in response to the request from the retransmission
request means and arriving through a predetermined retransmission
channel.
[0039] According to still another aspect of the present invention,
there is provided a radio broadcasting apparatus used in a radio
broadcasting system for radio-broadcasting a predetermined
transmission signal from the radio broadcasting apparatus to a
radio receiver, comprising means for receiving a retransmission
request from the radio receiver, and retransmission means for
transmitting a transmission signal of a requested portion using a
predetermined retransmission channel in response to the
request.
[0040] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for repeating a
broadcasting signal transmitted from a ground broadcasting station
with a satellite and broadcasting the broadcasting signal to a
predetermined service area on the ground, comprising a gap filler
apparatus comprising means for receiving the broadcasting signal
repeated by the satellite, and means for radio-transmitting a
signal having the same frequency as that of the broadcasting signal
transmitted from the satellite, to an area in the service area,
where the broadcasting signal from the satellite cannot be
received.
[0041] According to still another aspect of the present invention,
there is provided a gap filler apparatus used in a satellite
broadcasting system for transmitting a broadcasting signal to a
predetermined service area on the ground via a satellite,
comprising a first antenna for receiving the broadcasting signal
transmitted from the satellite, a radio circuit section for at
least amplifying the broadcasting signal received by the first
antenna and outputting a transmission broadcasting signal having
the same frequency as that of the received broadcasting signal, and
a second antenna for radio-transmitting the transmission
broadcasting signal output from the radio circuit section to an
area in the service area, where the broadcasting signal from the
satellite cannot be received. There is also provided a satellite
broadcasting system comprising a first satellite placed in a
predetermined orbit to transmit a broadcasting signal sent from a
ground broadcasting station to a predetermined service area on the
ground, and a second satellite placed in the same orbit as that of
the first satellite while being spaced apart from the first
satellite by a predetermined distance to synchronously transmit the
same broadcasting signal as that transmitted from the first
satellite to the service area.
[0042] According to still another aspect of the present invention,
there is provided a satellite broadcasting system comprising a
satellite for repeating a broadcasting signal transmitted from a
ground broadcasting station and transmitting the broadcasting
signal to a predetermined service area on the ground, a plurality
of broadcasting receivers each having a function of receiving and
reconstructing the broadcasting signal repeated by the satellite in
the service area, and a gap filler apparatus for receiving the
broadcasting signal repeated by the satellite and transmitting the
received broadcasting signal to an area in the service area, where
the broadcasting signal from the satellite cannot be received,
wherein the satellite comprises conversion means for converting the
broadcasting signal transmitted from the ground broadcasting
station into first and second broadcasting signals having different
frequencies and radio-transmitting the first and second
broadcasting signals, and the gap filler apparatus comprises means
for receiving the second broadcasting signal transmitted from the
satellite and converting the second broadcasting signal into a
third broadcasting signal having the same frequency as that of the
first broadcasting signal, and means for radio-transmitting the
third broadcasting signal to the area in the service area, where
the first broadcasting signal from the satellite cannot be
received.
[0043] According to still another aspect of the present invention,
there is provided a satellite broadcasting system comprising a
satellite for repeating a broadcasting signal transmitted from a
ground broadcasting station and transmitting the broadcasting
signal to a predetermined service area on the ground, a plurality
of broadcasting receivers each having a function of receiving and
reconstructing the broadcasting signal repeated by the satellite in
the service area, and a gap filler apparatus for receiving the
broadcasting signal repeated by the satellite and transmitting the
received broadcasting signal to an area in the service area, where
the broadcasting signal from the satellite cannot be received,
wherein the satellite comprises means for repeating a first
broadcasting signal transmitted from the ground broadcasting
station and a second broadcasting signal having the same contents
as those of the first broadcasting signal, and the gap filler
apparatus comprises means for receiving the second broadcasting
signal transmitted from the satellite and converting the second
broadcasting signal into, a third broadcasting signal having the
same frequency as that of the first broadcasting signal, and means
for radio-transmitting the third broadcasting signal to the area in
the service area, where the first broadcasting signal from the
satellite cannot be received.
[0044] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for repeating a
broadcasting signal transmitted from a ground broadcasting station
with a satellite and transmitting the broadcasting signal to a
predetermined service area on the ground, comprising ground network
transmission means for transmitting, through a ground network, a
second broadcasting signal having the same contents as those of a
first broadcasting signal transmitted from the ground broadcasting
station to the satellite, and a gap filler apparatus for receiving
the second broadcasting signal transmitted by the ground network
transmission means, converting the received second broadcasting
signal into a third broadcasting signal in the same frequency band
as that of the broadcasting signal transmitted from the satellite,
and radio-transmitting the third broadcasting signal to an area in
the service area, where the broadcasting signal from the satellite
cannot be received.
[0045] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for repeating a
broadcasting signal transmitted from a ground broadcasting station
with a satellite and transmitting the broadcasting signal to a
predetermined service area on the ground, comprising another
satellite for repeating a second broadcasting signal having the
same contents as those of a first broadcasting signal transmitted
from the ground broadcasting station to the satellite, and a gap
filler apparatus for receiving the second broadcasting signal
repeated by the other satellite, converting the received second
broadcasting signal into a third broadcasting signal in the same
frequency band as that of the broadcasting signal transmitted from
the satellite, and radio-transmitting the third broadcasting signal
to an area in the service area, where the broadcasting signal from
the satellite cannot be received.
[0046] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for repeating a
broadcasting signal transmitted from a ground broadcasting station
with a satellite and transmitting the broadcasting signal to a
predetermined service area on the ground, comprising ground network
transmission means for transmitting, through a ground network, a
second broadcasting signal having the same contents as those of a
first broadcasting signal transmitted from the ground broadcasting
station to the satellite, another satellite for repeating a second
broadcasting signal having the same contents as those of a first
broadcasting signal transmitted from the ground broadcasting
station to the satellite, and a gap filler apparatus for
selectively receiving one of the second broadcasting signal
transmitted by the ground network transmission means and the second
broadcasting signal repeated by the other satellite, converting the
received second broadcasting signal into a third broadcasting
signal in the same frequency band as that of the broadcasting
signal transmitted from the satellite, and radio-transmitting the
third broadcasting signal to an area in the service area, where the
broadcasting signal from the satellite cannot be received.
[0047] According to still another aspect of the present invention,
there is provided a gap filler apparatus used in a satellite
broadcasting system for repeating a broadcasting signal transmitted
from a ground broadcasting station with a satellite and
transmitting the broadcasting signal to a predetermined service
area on the ground, comprising ground network reception means for
receiving, from the ground broadcasting station through a ground
network, a second broadcasting signal having the same contents as
those of the broadcasting signal transmitted from the ground
broadcasting station to the satellite, conversion means for
converting the second broadcasting signal received by the ground
network reception means into a third broadcasting signal in the
same frequency band as that of the broadcasting signal transmitted
from the satellite, and transmission means for radio-transmitting
the third broadcasting signal obtained by the conversion means to
an area in the service area, where the broadcasting signal from the
satellite cannot be received.
[0048] According to still another aspect of the present invention,
there is provided a gap filler apparatus used in a satellite
broadcasting system for repeating a broadcasting signal transmitted
from a ground broadcasting station with a satellite and
transmitting the broadcasting signal to a predetermined service
area on the ground, comprising satellite reception means for
receiving the broadcasting signal transmitted from the satellite,
ground network reception means for receiving, through a ground
network, a second broadcasting signal having the same contents as
those of the broadcasting signal transmitted from the ground
broadcasting station to the satellite, conversion means for
converting the second broadcasting signal received by the ground
network reception means into a third broadcasting signal in the
same frequency band as that of the broadcasting signal transmitted
from the satellite, and selective transmission means for selecting
one of the broadcasting signal received by the satellite reception
means and the third broadcasting signal obtained by the conversion
means and radio-transmitting the selected signal to an area in the
service area, where the broadcasting signal from the satellite
cannot be received.
[0049] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for repeating a
broadcasting signal with a satellite and broadcasting the
broadcasting signal to a predetermined service area on the ground,
comprising a gap filler apparatus for receiving the broadcasting
signal repeated by the satellite and radio-transmitting the
received broadcasting signal to an area in the service area,
wherein the broadcasting signal from the satellite cannot be
received, and a monitor apparatus connected to the gap filler
apparatus through a communication line, wherein the gap filler
apparatus comprises monitor information transmission means for
generating monitor information representing an operation state of a
self apparatus and transmitting the monitor information to the
monitor apparatus through the communication line, and the monitor
apparatus comprises means for receiving the monitor information
transmitted from the gap filler apparatus through the communication
line, and performing predetermined processing of monitoring the
operation state of the gap filler apparatus on the basis of the
received monitor information.
[0050] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for repeating a
broadcasting signal with a satellite and broadcasting the
broadcasting signal to a predetermined service area on the ground,
comprising a gap filler apparatus for receiving the broadcasting
signal repeated by the satellite and radio-transmitting the
received broadcasting signal to an area in the service area,
wherein the broadcasting signal from the satellite cannot be
received, a monitor receiver set in the reception disabled area and
having a function of receiving the received broadcasting signal
transmitted from the gap filler apparatus, and a monitor apparatus
connected to the monitor receiver through a communication line,
wherein the gap filler apparatus comprises means for generating
monitor information representing an operation state of a self
apparatus, inserting the monitor information into the received
broadcasting signal, and radio-transmitting the broadcasting
signal, the monitor receiver comprises means for receiving the
received broadcasting signal transmitted from the gap filler
apparatus and extracting the monitor information from the received
broadcasting signal, means for detecting a reception state of the
received broadcasting signal, and means for transmitting the
extracted monitor information and detection information of the
reception state to the monitor apparatus through the communication
line, and the monitor apparatus comprises means for receiving the
monitor information and the detection information, which are
transmitted from the monitor receiver through the communication
line, and performing predetermined processing of monitoring the
operation state of the gap filler apparatus on the basis of the
received monitor information and detection information.
[0051] According to still another aspect of the present invention,
there is provided a satellite broadcasting system in which a
plurality of channel signals having different center frequencies
are transmitted from a transmission station to a satellite placed
in a geostationary orbit, and the channel signals are transmitted
from the satellite to a service area and received by a reception
terminal, the satellite comprising signal reception means for
receiving the plurality of channel signals transmitted from the
transmission station, classification means for frequency-converting
the channel signals received by the reception means and classifying
the signals in accordance with frequency positions, polarization
setting means for amplifying the channel signals classified by the
classification means and then setting, for each channel signal,
right circular polarization or left circular polarization in
accordance with classification, and signal transmission means for
transmitting the channel signals for which polarization is set by
the polarization setting means, and the reception terminal
comprising reception means for receiving the channel signals
transmitted from the signal transmission means, polarization
processing means for selecting circular polarization corresponding
to selected channels of the channel signals received by the
reception means, and channel selection means for selecting a
desired channel signal from the channel signals for which circular
polarization is selected by the polarization processing means.
[0052] According to still another aspect of the present invention,
there is provided a satellite broadcasting system in which a
plurality of channel signals having different center frequencies
are transmitted from a transmission station to a satellite placed
in a geostationary orbit, and the channel signals are transmitted
from the satellite to a service area and received by a reception
terminal, the satellite comprising signal reception means for
receiving the plurality of channel signals transmitted from the
transmission station, classification means for frequency-converting
the channel signals received by the reception means and classifying
the signals in accordance with frequency positions, polarization
setting means for amplifying the channel signals classified by the
classification means and then setting, for each channel signal,
vertical polarization or horizontal polarization in accordance with
classification, and signal transmission means for transmitting the
channel signals for which polarization is set by the polarization
setting means, and the reception terminal comprising reception
means for receiving the channel signals transmitted from the signal
transmission means, polarization processing means for selecting
linear polarization corresponding to selected channels of the
channel signals received by the reception means, and channel
selection means for selecting a desired channel signal from the
channel signals for which linear polarization is selected by the
polarization processing means.
[0053] According to still another aspect of the present invention,
there is provided a reception terminal comprising reception means
for receiving a plurality of right- or left-circularly polarized
channel signals, and channel selection means for selecting circular
polarization corresponding to selected channels for the channel
signals received by the reception means and outputting the channel
signals.
[0054] According to still another aspect of the present invention,
there is provided a reception terminal comprising reception means
for receiving a plurality of vertically or horizontally polarized
channel signals, polarization processing means for selecting linear
polarization corresponding to selected channels for the channel
signals received by the reception means, and channel selection
means for selecting a desired channel signal from the channel
signals for which linear polarization is selected by the
polarization processing means.
[0055] According to still another aspect of the present invention,
there is provided a satellite broadcasting system for providing
digital broadcasting using a geostationary satellite placed in a
geostationary orbit above the equator, comprising a reception
antenna mounted on the geostationary satellite to receive digital
signals of a plurality of channels sent to the geostationary
satellite, a signal processing unit mounted on the geostationary
satellite to signal-convert the digital signals of the plurality of
channels received by the reception antenna, power-amplify the
signals, and output the signals, and a transmission antenna mounted
on the geostationary satellite and comprising a primary radiator
for radiating the digital channels of the plurality of channels
output from the signal processing unit and a reflecting mirror for
radiating a radio wave radiated by the primary radiator to a
specific area to form a transmission beam, the reflecting mirror
having a diameter for obtaining a power strength receivable by a
receiver for satellite broadcasting in the specific area.
[0056] According to still another aspect of the present invention,
there is provided a satellite broadcasting receiver for receiving
digital broadcasting using a geostationary satellite placed in a
geostationary orbit above the equator, comprising a microphone for
converting speech of a user into an electrical signal, speech
recognition means for recognizing a channel designated by the user
from the electrical signal obtained by the microphone, and
reception means for receiving, from broadcasting signals
transmitted from the geostationary satellite, the channel
recognized by the speech recognition means.
[0057] According to still another aspect of the present invention,
there is provided a satellite broadcasting receiver for receiving
digital broadcasting using a geostationary satellite placed in a
geostationary orbit above the equator, comprising fatigue state
estimation means for detecting a fatigue state of a driver of a
mobile on the basis of a moving state of the mobile carrying the
satellite broadcasting receiver, and reception means for receiving,
from broadcasting signals transmitted from the geostationary
satellite, a channel corresponding to the fatigue state detected by
the fatigue state estimation means.
[0058] According to still another aspect of the present invention,
there is provided a satellite broadcasting receiver for receiving
digital broadcasting using a geostationary satellite placed in a
geostationary orbit above the equator, comprising timepiece means
for counting time, view data detection means for detecting a
channel received by the satellite broadcasting receiver and a
reception time, an interface connectable to a recording medium
on/from which data can be written/read, and view data recording
control means for recording, on the recording medium connected to
the interface, the reception channel and time detected by the view
data detection means in correspondence with each other.
BRIEF DESCRIPTION OF DRAWINGS
[0059] FIG. 1 is a schematic view showing a satellite broadcasting
system according to the first embodiment of the present
invention.
[0060] FIG. 2 is a block diagram showing the arrangement of a
ground broadcasting station in the first embodiment.
[0061] FIG. 3 is a block diagram showing the arrangement of a
geostationary satellite in the second embodiment of the present
invention.
[0062] FIG. 4 is a block diagram showing the arrangement of a
ground broadcasting station in the third embodiment of the present
invention.
[0063] FIG. 5 is a block diagram showing the arrangement of a
broadcasting receiver in the third embodiment.
[0064] FIG. 6 is a block diagram showing the arrangement of a
geostationary satellite in the fourth embodiment of the present
invention.
[0065] FIG. 7 is a block diagram showing the arrangement of a
geostationary satellite in the fifth embodiment of the present
invention.
[0066] FIG. 8 is a block diagram showing the arrangement of a
geostationary satellite in the sixth embodiment of the present
invention.
[0067] FIG. 9 is a block diagram showing the arrangement of a
ground broadcasting station in the sixth embodiment.
[0068] FIGS. 10A and 10B are timing charts used to explain the
operation of the sixth embodiment.
[0069] FIG. 11 is a view showing the schematic arrangement of a
satellite broadcasting system according to the seventh to ninth
embodiments of the present invention.
[0070] FIG. 12 is a perspective view showing the outer appearance
of a broadcasting satellite SAT in FIG. 11.
[0071] FIG. 13 is a view showing the arrangement of a satellite
broadcasting receiver according to the seventh embodiment of the
present invention.
[0072] FIG. 14 is a perspective view showing an example of antenna
set state on a mobile in the seventh embodiment.
[0073] FIGS. 15A to 15C are views showing a change in radio wave
arrival at the satellite broadcasting receiver shown in FIG. 13
when a mobile having the satellite broadcasting receiver moves
under an obstacle.
[0074] FIGS. 16A and 16B are views showing a change in radio wave
arrival at the satellite broadcasting receiver shown in FIG. 13
when the mobile having the satellite broadcasting receiver moves
under the obstacle.
[0075] FIG. 17 is a view showing a modification of the satellite
broadcasting receiver according to the seventh embodiment.
[0076] FIG. 18 is a view showing the arrangement of a satellite
broadcasting receiver according to the eighth embodiment of the
present invention.
[0077] FIG. 19 is a view showing the arrangement of a satellite
broadcasting system according to the ninth embodiment of the
present invention.
[0078] FIG. 20 is a schematic view showing a satellite broadcasting
system having a gap filler function according to the 10th
embodiment of the present invention.
[0079] FIG. 21 is a block diagram showing the arrangement of a gap
filler apparatus used in the satellite broadcasting system
according to the 10th embodiment.
[0080] FIG. 22 is a plan view for explaining a satellite
broadcasting system according to the 11th embodiment of the present
invention.
[0081] FIG. 23 is a front view for explaining the satellite
broadcasting system according to the 11th embodiment.
[0082] FIG. 24 is a view for explaining coverage of a dead area in
the satellite broadcasting system according to the 11th
embodiment.
[0083] FIG. 25 is a view for explaining coverage of the dead area
in the satellite broadcasting system according to the 11th
embodiment.
[0084] FIG. 26 is a block diagram showing the arrangement of a
transmission section of a ground broadcasting station used in a
satellite broadcasting system having a gap filler function
according to the 12th embodiment of the present invention.
[0085] FIG. 27 is a block diagram showing the arrangement of a
broadcasting receiver used in the satellite broadcasting system
having a gap filler function according to the 12th embodiment.
[0086] FIG. 28 is a block diagram showing the arrangement of the
receiver of the broadcasting receiver shown in FIG. 27.
[0087] FIG. 29 is a schematic view showing a satellite broadcasting
system having a gap filler function according to the 13th
embodiment of the present invention.
[0088] FIG. 30 is a schematic view showing a satellite broadcasting
system having a gap filler function according to the 14th
embodiment of the present invention.
[0089] FIG. 31 is a block diagram showing the arrangement of a
transponder of a geostationary satellite used in the system shown
in FIG. 30.
[0090] FIG. 32 is a block diagram showing the arrangement of a gap
filler apparatus used in the system shown in FIG. 30.
[0091] FIG. 33 is a schematic view showing a satellite broadcasting
system having a gap filler function according to the 15th
embodiment of the present invention.
[0092] FIG. 34 is a schematic view showing a modification of the
system shown in FIG. 33.
[0093] FIG. 35 is a schematic view showing the first arrangement of
a satellite broadcasting system having a gap filler function
according to the 16th embodiment of the present invention.
[0094] FIG. 36 is a schematic view showing the second arrangement
of the satellite broadcasting system having the gap filler function
according to the 16th embodiment.
[0095] FIG. 37 is a schematic view showing the third arrangement of
the satellite broadcasting system having the gap filler function
according to the 16th embodiment.
[0096] FIG. 38 is a view showing the schematic arrangement of a
satellite broadcasting system according to the 17th embodiment of
the present invention.
[0097] FIG. 39 is a view showing the arrangement of a transmission
station shown in FIG. 38.
[0098] FIG. 40 is a view showing the arrangement of a geostationary
satellite shown in FIG. 38.
[0099] FIG. 41 is a view showing a reception terminal according to
the 17th embodiment.
[0100] FIG. 42 is a view showing the receiver of the reception
terminal shown in FIG. 41.
[0101] FIG. 43 is a schematic view showing a satellite broadcasting
system according to the 18th embodiment of the present
invention.
[0102] FIG. 44 is a perspective view showing the specific outer
appearances of a geostationary satellite used in the system of the
18th embodiment and an antenna carried by the satellite.
[0103] FIG. 45 is a view showing an example of division of service
areas when a multibeam scheme is employed in the system of the 18th
embodiment.
[0104] FIG. 46 is a perspective view showing the outer appearance
of a receiver for receiving a satellite broadcasting wave of the
system of the 18th embodiment.
[0105] FIG. 47 is a block diagram showing the internal circuit
arrangement of the receiver for receiving a satellite broadcasting
wave of the system of the 18th embodiment.
[0106] FIGS. 48A and 48B are views showing the directivity
characteristics of an antenna used in the receiver for receiving a
satellite broadcasting wave of the system of the 18th
embodiment.
[0107] FIG. 49 is a block diagram showing the arrangement of an
MPEG4 image transmission apparatus applicable to the system of the
18th embodiment.
[0108] FIGS. 50A and 50B are views showing an example of the
broadcasting screen layout in the system of the 18th
embodiment.
[0109] FIG. 51 is a block diagram showing the arrangement of a
satellite broadcasting receiver according to the 19th embodiment of
the present invention.
[0110] FIG. 52 is a view showing a display example of a selection
window of hierarchical reception channels stored in the program
data storage area of the satellite broadcasting receiver shown in
FIG. 51.
BEST MODE OF CARRYING OUT THE INVENTION
[0111] The present invention will be described in more detail with
reference to the accompanying drawings.
[0112] The first aspect of the present invention will be described
throughout the first to sixth embodiments.
[0113] (First Embodiment)
[0114] FIG. 1 is a schematic view showing a satellite broadcasting
system according to the first embodiment of the present
invention.
[0115] This satellite broadcasting system includes a plurality of
ground broadcasting stations (VSAT) BC1 and BC2 or feeder link
stations, a geostationary satellite SAT, and a satellite tracking
control station STCC.
[0116] Each of the ground broadcasting stations (VSAT) BC1 and BC2
or the feeder link stations transmits program information prepared
and edited by a broadcaster to the geostationary satellite SAT
through an uplink transmission channel in the Ka band (26.5 to 40
GHz) or the Ku band (12.5 to 18 GHz).
[0117] The geostationary satellite SAT has a Ka-band or Ku-band
antenna having a diameter of 2.5-m class and an S-band (e.g., 2.6
GHz) antenna having a diameter of 15-m class. A broadcasting signal
multiplexed and transmitted from one of the broadcasting stations
(VSAT) BC1 and BC2 or the feeder link stations is received and
amplified by the Ka- or Ku-band antenna and then converted into a
signal for the S band. The converted broadcasting signal is
transmitted from the S-band antenna to a service area through a
downlink transmission channel in the S band. The uplink
transmission antenna carried by the geostationary satellite SAT may
have a diameter smaller than 2.5-m class. The S-band antenna may
also have a diameter of not 15-m class but 8-m class.
[0118] The satellite tracking control station STCC monitors and
controls the operation state of the geostationary satellite
SAT.
[0119] In the service area, a broadcasting receiver (not shown)
stationarily set, e.g., in an office or at home or a movable
broadcasting receiver MS carried by an automobile or carried as a
portable device receives the broadcasting signal transmitted from
the geostationary satellite SAT to the S-band downlink transmission
channel in the S band. In the S-band downlink transmission channel,
a plurality of channels, a maximum of 900 channels having a
transmission rate of 64 to 256 Kbps/channel are multiplexed. To
transmit a video signal using a channel, MPEG4 (moving picture
experts group 4) is used as a video coding method.
[0120] Each of the ground broadcasting stations BC1 and BC2 of the
first embodiment has a function of matching the phases of spreading
codes between a plurality of channels when a plurality of programs
are to be subjected to code division multiplex and transmitted and
has the following arrangement. FIG. 2 is a block diagram showing
the arrangement of the transmission section.
[0121] Broadcasting signals of a plurality of programs (N programs
in FIG. 2) edited by a circuit (not shown) are input to modulators
111 to 11n, respectively. The spread modulators 111 to 11n
spread-spectrum-modulate the broadcasting signals using different
spreading codes generated from spreading code generators 121 to
12n, respectively. The broadcasting signals
spread-spectrum-modulated by the spread modulators 111 to 11n are
synthesized into one code division multiplex (CDM) broadcasting
signal by a synthesizer 131 and input to a modulator 132. The
modulator 132 further modulates the CDM broadcasting signal by
digital modulation such as QPSK or QAM. The modulated CDM
broadcasting signal is frequency-converted into a Ka- or Ku-band
radio signal by a transmitter 133. The radio signal is amplified to
a predetermined transmission power level and then transmitted from
an antenna 134 to the geostationary satellite.
[0122] The ground broadcasting station MS has a control circuit
140. The control circuit 140 generates a reference phase signal for
designating the reference phase of a spreading code and supplies it
to the spreading code generators 121 to 12n. The spreading code
generators 121 to 12n start to generate spreading codes in
synchronism with the reference phase signal supplied from the
control circuit 140.
[0123] With this arrangement, the broadcasting signals of the
programs are spread-modulated by the spread modulators 111 to 11n
using the spreading codes generated from the spreading code
generators 121 to 12n in synchronism with the reference phase,
respectively. For this reason, the CDM broadcasting signal output
from the synthesis circuit 131 has spreading code phases matched
between the channels, so the CDM broadcasting signal having matched
spreading code phases is broadcasted to the broadcasting receiver
MS through the geostationary satellite SAT.
[0124] Spreading code synchronization is established for one of the
channels in the CDM broadcasting signal arriving through the
geostationary satellite SAT upon, e.g., powering on, and then, the
spreading codes corresponding to all channels are generated in
phase. Even when switching to another channel is performed, the
broadcasting receiver MS can receive the channel in a very short
time only by switching the spreading code without newly
establishing spreading code synchronization to the channel.
[0125] (Second Embodiment)
[0126] In the second embodiment of the present invention, a
geostationary satellite SAT detects the spreading code phase
difference between the channels of a CDM broadcasting signal
arriving from each of a ground broadcasting station BC1 or BC2,
matches the spreading code phases between the channels on the basis
of the detection result, and then transmits a signal to a
broadcasting receiver MS.
[0127] FIG. 3 is a block diagram showing the arrangement of the
geostationary satellite SAT according to the second embodiment.
Referring to FIG. 3, a CDM broadcasting signal transmitted from the
ground broadcasting station BC1 or BC2 is received by a Ku-band
reception antenna 151 and input to a reception circuit 152. The CDM
broadcasting signal is low-noise-amplified, down-converted into an
IF signal, and distributed to k correlators 161 to 16k. The number
of correlators 161 to 16k is set in correspondence with a total
number k of channels to be multiplexed/transmitted by the ground
broadcasting station BC1 or BC2. The correlators 161 to 16k
despread the spectrum of the received IF signal using spreading
codes which are set in advance in units of channels. The despread
reception signals are input to spread modulation circuits 171 to
17k, respectively.
[0128] When the spectrum of the received IF signal is to be
despread, each of the correlators 161 to 16k correlates the
received IF signal with a spreading code (a quadrature code such as
a Walsh code or a Gold code prepared independently of the PN code)
and inputs the correlation value to a control circuit 180. The
control circuit 180 detects the phase difference between a
quadrature code generated in the geostationary satellite SAT with
the received quadrature code on the basis of the correlation value
input from each of the correlators 161 to 16k in units of channels.
A phase control signal for making the detected phase difference
zero is generated in units of channels and supplied to a
corresponding one of the spread modulation circuits 171 to 17k.
[0129] Each of the spread modulation circuits 171 to 17k adjusts
the spreading code generation phase on the basis of the phase
control signal supplied from the control circuit 180. The spectra
of the received signals input from the correlators 161 to 16k are
spread using the spreading codes, and the spread broadcasting
signals are input to a synthesis circuit 153. The synthesis circuit
153 synthesizes the broadcasting signals output from the spread
modulators 171 to 17k. The CDM broadcasting signal obtained by
synthesis is input to a frequency conversion circuit 154.
[0130] The frequency conversion circuit 154 frequency-converts the
CDM broadcasting signal into a frequency in the S band (2.6 GHz),
which is assigned to the self system in advance, and inputs the
signal to a transmitter 155. The transmitter 155 amplifies the
frequency-converted CDM broadcasting signal to a predetermined
transmission power level and transmits the CDM broadcasting signal
from an S-band transmission antenna 156 to a service area.
[0131] With this arrangement, the phase difference between the
spreading codes of the channel signals in the CDM broadcasting
signal transmitted from the ground broadcasting station BC1 or BC2
is detected in the geostationary satellite SAT. The spectra of the
channel signals are spread again using spreading codes
phase-controlled to make the detected phase difference zero and
then transmitted to the service area in the S band. For this
reason, even when the spreading code phases do not match between
the channels of the CDM broadcasting signal arriving from the
ground broadcasting station BC1 or BC2, the CDM broadcasting signal
is transmitted and received by the broadcasting receiver MS after
the phase difference is absorbed in the geostationary satellite
SAT.
[0132] Spreading code synchronization is established for one of the
channels in the CDM broadcasting signal arriving through the
geostationary satellite SAT upon, e.g., powering on. Even when
switching to another channel is performed, the broadcasting
receiver MS can receive the channel in a very short time only by
switching the spreading code without newly establishing spreading
code synchronization to the channel.
[0133] (Third Embodiment)
[0134] In the third embodiment of the present invention, a ground
broadcasting station BC1 or BC2 detects the spreading code phase
difference between channels in generating a CDM broadcasting signal
and transmitting the CDM broadcasting signal, and the phase
difference information is multiplexed to the CDM broadcasting
signal and transmitted. In selectively receiving one of the
channels of the CDM broadcasting signal arriving through a
geostationary satellite SAT, a broadcasting receiver MS initializes
the chip phase of the spreading code on the basis of the phase
difference information received together with the CDM broadcasting
signal, and selectively despreads the spectrum of the broadcasting
signal of each channel using the spreading code to reconstruct the
broadcasting signal.
[0135] FIG. 4 is a block diagram showing the arrangement of the
transmission section of each of the ground broadcasting stations
BC1 and BC2 according to this embodiment. The same reference
numerals as in FIG. 2 denote the same parts in FIG. 4, and a
detailed description thereof will be omitted.
[0136] Spreading codes generated from spreading code generators 121
to 12n are input to a phase difference information transmission
circuit 141. The phase difference information transmission circuit
141 detects the phase difference of each spreading code from the
reference phase. Information representing the phase difference is
coded and primary-modulated and input to a spread modulator 143.
The spread modulator 143 spreads the spectrum of the phase
difference information input from the phase difference information
transmission circuit 141 using a spreading code generated from a
spread modulator 42 and inputs the phase difference information to
a synthesis circuit 135. The synthesis circuit 135 synthesizes the
spread-modulated signal of each of the channel broadcasting signals
output from spread modulators 111 to 11n with the spread-modulated
signal of the phase difference information output from the spread
modulator 142 and supplies the synthesized signal to a modulator
132 for transmission.
[0137] The broadcasting receiver MS has the following arrangement.
FIG. 5 is a block diagram showing the arrangement of the
broadcasting receiver MS. The CDM broadcasting signal arriving from
the geostationary satellite SAT is received by an S-band reception
antenna 191, input to a reception circuit 192, low-noise-amplified,
and frequency-converted into an IF signal. The received IF signal
is distributed to first and second correlators 193 and 194.
[0138] The first correlator 193 despreads the spectrum of the
received IF signal using a spreading code corresponding to a
reception channel designated from a control circuit 190, and inputs
the despread channel signal to a detector (DET) 195. The reception
channel is designated by the user by operating a remote-control
operation section 197. The detector 195 detects the channel signal
by a detection method corresponding to, e.g., QPSK. The obtained
received broadcasting signal is input to an audio/video separation
circuit 1101.
[0139] The audio/video separation circuit 1101 separates the
reconstructed reception signal into audio data, video data, and
additional data such as text data. The separated received audio
data is input to an audio decoder 1102. The received video signal
is input to a video decoder 1104. The additional data is input to
an additional data decoder 1103. The audio decoder 1102 decodes the
received audio data to reconstruct the audio signal, and the audio
signal is amplified and output from a loudspeaker 1105. The video
decoder 1104 decodes the received video data by MPEG4 and causes a
display device 1106 constituted by, e.g., a liquid crystal display
to display the decoded video signal. The additional data decoder
1103 decodes the additional data such as text data and causes the
display device 1106 to display the decoded data together with the
video signal.
[0140] The second correlator 194 despreads the spectrum of the
received IF signal output from the reception circuit 192 using a
spreading code prepared in advance for transmission of phase
difference information. The phase difference information signal
obtained by despreading is detected by a detector 196, decoded, and
input to the control circuit 190.
[0141] Every time the operation section 197 switches channels, the
control circuit 190 designates a spreading code corresponding to
the designated channel for the first correlator 193 and also
designates the spreading code generation phase set on the basis of
the phase difference information. For this reason, the first
correlator 193 generates the spreading code corresponding to the
reception channel, designated by the control circuit 190, from the
designated chip phase, so the spectrum of the received IF signal is
despread using this spreading code.
[0142] In this system, information representing the spreading code
phase difference between the channels is multiplexed on the CDM
broadcasting signal and transmitted from the ground broadcasting
station BC1 or BC2 together with the CDM broadcasting signal. The
broadcasting receiver MS separates and extracts the phase
difference information from the CDM broadcasting signal. The chip
phase of the spreading code is initialized on the basis of the
phase difference information, so the spectrum of the broadcasting
signal of a desired channel is despread using this spreading code
to reconstruct the broadcasting signal.
[0143] Even when, in spreading the spectra of the broadcasting
signals of channels using spreading codes and transmitting them,
the ground broadcasting station BC1 or BC2 spreads the spectra of
the broadcasting signals of the channels without synchronizing the
spreading codes of the channels, the broadcasting receiver MS
initializes the chip phases of the spreading codes on the basis of
the phase difference information sent from the ground broadcasting
station BC1 or BC2 together with the CDM broadcasting signal so
that the spectrum of the CDM broadcasting signal is despread using
the spreading code. For this reason, as compared to a case wherein
the spreading code of each channel is searched for to establish
synchronization, spreading code synchronization for each channel
can be established in a short time. Therefore, the channels can be
quickly switched at a high response speed
[0144] (Fourth Embodiment)
[0145] In the fourth embodiment of the present invention, when a
ground broadcasting station BC1 or BC2 is to generate a CDM
broadcasting signal and transmit it, the phase difference between
the spreading codes of channels is detected, and the phase
difference information is multiplexed on the CDM broadcasting
signal and transmitted. In a geostationary satellite SAT, the phase
difference information is separated and extracted. Using a
spreading code whose phase is set on the basis of the phase
difference information, the spectrum of each channel signal of the
CDM broadcasting signal is newly spread, and the signal is
transmitted to a service area.
[0146] FIG. 6 is a block diagram showing the arrangement of the
geostationary satellite SAT according to this embodiment. The same
reference numeral as in FIG. 3 denote the same parts in FIG. 6, and
a detailed description thereof will be omitted.
[0147] The geostationary satellite SAT has not only a group of
correlators 161 to 16k for despreading the spectra of the CDM
broadcasting signal in units of channels but also a correlator 157
for separating and extracting the phase difference information. The
correlator 157 despreads the spectrum of the received IF signal
output from a reception circuit 152 using a spreading code which is
set in advance for transmission of the phase difference
information, thereby separating and extracting the phase difference
information.
[0148] A control circuit 181 generates phase control signals for
designating the chip phases of the spreading codes of the channels
on the basis of the phase difference information separated and
extracted by the correlator 157 and supplies the phase control
signals to spread modulation circuits 171 to 17k, respectively.
[0149] Each of the spread modulation circuits 171 to 17k
initializes the chip phase of the spreading code on the basis of
the phase control signal and newly spreads the spectrum of the
channel signal, which has temporarily been despread by a
corresponding one of the correlators 161 to 16k, using the
spreading code with the initialized phase. The spectra of the
channel signals newly spread by the spread modulation circuits 171
to 17k are synthesized into a CDM broadcasting signal by a
synthesis circuit 153. The CDM broadcasting signal is converted
into a frequency in the S band by a frequency conversion circuit
154, amplified to a predetermined transmission power level by a
transmitter 155, and then transmitted from an S-band transmission
antenna 156 to a ground service area.
[0150] With this arrangement, even when the ground broadcasting
station BC1 or BC2 spreads the spectra of the broadcasting signals
of channels without synchronizing the spreading codes of the
channels, the spectrum of the CDM broadcasting signal transmitted
from the ground broadcasting station BC1 or BC2 is newly spread in
the geostationary satellite SAT on the basis of phase difference
information simultaneously transmitted from the ground broadcasting
station BC1 or BC2, and transmitted to the ground service area.
[0151] A broadcasting receiver MS receives the CDM broadcasting
signal wherein spreading code synchronization between channels is
established. For this reason, once spreading code synchronization
is established for any one of the channels of the CDM broadcasting
signal, the broadcasting receiver MS can separate the broadcasting
signal of a desired channel and reconstruct it only by switching
the spreading code without newly establishing spreading code
synchronization for the remaining channels. Therefore, the channels
can be quickly switched at a high response speed. In addition, in
this embodiment, the broadcasting receiver MS need not have a
circuit for initializing the spreading code generation phase for
each channel on the basis of the phase difference information, so
the arrangement of the broadcasting receiver MS can be
simplified.
[0152] (Fifth Embodiment)
[0153] In the fifth embodiment of the present invention, the phase
difference of the spreading code of each channel of a CDM
broadcasting signal, arriving from a ground broadcasting station
BC1 or BC2, from a reference phase is detected in a geostationary
satellite SAT, and the detected phase difference information is
multiplexed on the CDM broadcasting signal and transmitted to a
ground service area. Upon selectively receiving the channels of the
CDM broadcasting signal, a broadcasting receiver MS initializes the
chip phases of the spreading codes on the basis of the phase
difference information which has been received together with the
CDM broadcasting signal, so the spectrum of the broadcasting signal
of each channel is selectively despread using the spreading code to
reconstruct the broadcasting signal.
[0154] FIG. 7 is a block diagram showing the arrangement of the
geostationary satellite SAT according to this embodiment. The same
reference numeral as in FIG. 3 denote the same parts in FIG. 7, and
a detailed description thereof will be omitted.
[0155] The CDM broadcasting signal arriving from the ground
broadcasting station BC1 or BC2 is received by a reception antenna
151, and then low-noise-amplified and converted into an IF signal
by a reception circuit 152. The received IF signal is distributed
to correlators 161 to 16k which are arranged in correspondence with
the total number of channels to be transmitted from the ground
broadcasting station BC1 or BC2.
[0156] Each of the correlators 161 to 16k correlates the received
IF signal with a spreading code and inputs the correlation value to
a control circuit 182. The control circuit 182 detects the phase
difference between a quadrature code generated by the geostationary
satellite SAT and the received quadrature code on the basis of the
correlation value input from a corresponding one of the correlators
161 to 16k in units of channels. Information representing the phase
difference detected in units of channels is coded and input to a
spread modulation circuit 158.
[0157] The spread modulation circuit 158 spreads the spectrum of
the phase difference information using the spreading code, and the
spread phase difference information is input to a synthesis circuit
159. The synthesis circuit 159 synthesizes the spread signal of the
phase difference information with the CDM broadcasting signal
output from the reception circuit 152. The CDM broadcasting signal
obtained by synthesis is frequency-converted into a frequency in
the S-band by a frequency conversion circuit 154, amplified to a
predetermined transmission power level by a transmitter 155, and
then transmitted from an S-band transmission antenna 156 to the
ground service area.
[0158] As the broadcasting receiver to be used in this embodiment,
the same arrangement as that described in the third embodiment with
reference to FIG. 5 can be used.
[0159] With this arrangement, when the geostationary satellite SAT
receives the CDM signal transmitted from the ground broadcasting
station BC1 or BC2, the phase difference between the spreading code
of each channel and the reference phase is detected in the
geostationary satellite SAT. The information representing the phase
difference is multiplexed to the CDM signal and supplied to the
broadcasting receiver MS.
[0160] The broadcasting receiver MS separates and extracts the
phase difference information from the CDM broadcasting signal and
initializes the chip phases of the spreading codes on the basis of
the phase difference information, so the spectrum of the
broadcasting signal of a desired channel is despread using the
spreading code to reconstruct the broadcasting signal.
[0161] Even when, in spreading the spectrum of the broadcasting
signals of channels using spreading codes and transmitting them,
the ground broadcasting station BC1 or BC2 spreads the spectra of
the broadcasting signals of the channels without synchronizing the
spreading codes of the channels, the broadcasting receiver MS
initializes the chip phases of the spreading codes on the basis of
the phase difference information sent from the ground broadcasting
station BC1 or BC2 together with the CDM broadcasting signal so
that the spectrum of the CDM broadcasting signal is despread using
the spreading code. For this reason, as compared to a case wherein
the spreading code of each channel is searched for to establish
synchronization, spreading code synchronization for each channel
can be established in a short time. Therefore, the channels can be
quickly switched at a high response speed.
[0162] In addition, according to this embodiment, the ground
broadcasting station BC1 or BC2 need not have a circuit for
detecting the phase difference between the spreading codes of the
channels and multiplex/transmitting the detection information, so
the circuit arrangement of the ground broadcasting station BC1 or
BC2 can be simplified.
[0163] (Sixth Embodiment)
[0164] In the sixth embodiment of the present invention, the
spreading code phase difference between CDM broadcasting signals
transmitted from a plurality of ground broadcasting stations BC1,
BC2, and BC3 is detected in a geostationary satellite SAT. A phase
control signal for making the phase difference zero is supplied
from the geostationary satellite SAT to each of the ground
broadcasting stations BC1, BC2, and BC3 as sources. Each of the
ground broadcasting stations BC1, BC2, and BC3 variably controls
the transmission timing of the broadcasting signal to be
transmitted from the self apparatus on the basis of the supplied
phase difference information such that the spreading code phase
difference between the CDM broadcasting signals transmitted from
the ground broadcasting stations BC1, BC2, and BC3 becomes zero on
the geostationary satellite SAT.
[0165] FIG. 8 is a block diagram showing the arrangement of the
geostationary satellite SAT according to this embodiment. In FIG.
8, the CDM broadcasting signal transmitted from each of the ground
broadcasting stations BC1, BC2, and BC3 is received by a reception
antenna 1111 and amplified by a low-noise amplifier 1112. The
received CDM broadcasting signal is frequency-converted from the Ku
band to the S band by a frequency conversion circuit 1113,
amplified to a predetermined transmission power level by a
transmission power amplifier 1114, and transmitted from an S-band
transmission antenna 1115 to a ground service area.
[0166] The received CDM broadcasting signal output from the
low-noise amplifier 1112 is input to a reception circuit 1121,
frequency-converted into, e.g., an IF signal, and then distributed
to correlators 1131 to 113k. The number of correlators 1131 to 113k
corresponds to a total number k of channels to be
multiplexed/transmitted by each of the ground broadcasting stations
BC1 and BC2.
[0167] Each of the correlators 1131 to 113k correlates the received
IF signal with a spreading code and inputs the correlation value to
a phase difference detection circuit 1122. The phase difference
detection circuit 1122 detects the phase difference between a
spreading code generated by the geostationary satellite SAT and
each received spreading code on the basis of the correlation value
input from a corresponding one of the correlators 1131 to 113k in
units of channels. A phase control signal for making the detected
phase difference zero is generated in units of channels, and the
phase control signals are input to modulation circuits (MOD) 1141
to 114k, respectively.
[0168] Each of the modulation circuits 1141 to 114k performs, for
the phase control signal, primary modulation such as QPSK and
spread spectrum modulation using a spreading code for phase control
signal transmission. The spread-modulated signals output from the
modulation circuits 1141 to 114k are synthesized to one signal by a
synthesis circuit 1123 and input to a transmitter 1124 as a CDM
phase control signal. The transmitter 1124 performs processing of
frequency-converting the CDM phase control signal into a signal in
the Ku band and processing of amplifying the frequency-converted
transmission signal in the Ku band to a predetermined transmission
power level. The CDM phase control signal output from the
transmitter 1124 is transmitted from a Ku-band transmission antenna
1125 to the ground broadcasting station BC1 or BC2 as a source
through a Ku-band downlink transmission channel.
[0169] Each of the ground broadcasting stations BC1 and BC2 has the
following arrangement. FIG. 9 is a block diagram showing the
arrangement of the transmission section. The same reference
numerals as in FIG. 2 denote the same parts in FIG. 9.
[0170] The CDM phase difference control signal sent from the
geostationary satellite SAT through the Ku-band downlink
transmission channel is received by a reception antenna 144, input
to a receiver 145, low-noise-amplified, and frequency-converted
into an IF signal. The spectrum of the received IF signal is
despread by a correlator 146 using a spreading code for phase
control signal transmission. The resultant reception signal is
detected by a detector (DET) 147 using a detection method
corresponding to, e.g., QPSK. The reconstructed phase control
signal is input to a control circuit 148.
[0171] The control circuit 148 supplies the reconstructed phase
control signal to a corresponding one of spreading code generators
121 to 12n in units of channels. The spreading code generators 121
to 12n correct the spreading code generation start phases to
timings given by the phase control signals. Accordingly, each of
spread modulators 111 to 11n spreads the spectrum of the
broadcasting signal of each program using the spreading code whose
generation timing is corrected by a corresponding one of the
spreading code generators 121 to 12n.
[0172] The spread-modulated signals of the broadcasting signals
output from the spread modulators 111 to 11n are synthesized into
one signal by a synthesis circuit 121 and input to a modulator 132.
The signal is modulated, frequency-converted into a transmission
signal in the Ku band by a transmitter 133, amplified to a
predetermined transmission power level, and transmitted from a
transmission antenna 134 to the geostationary satellite SAT.
[0173] With this arrangement, in the geostationary satellite SAT,
the spreading code phase difference between the CDM broadcasting
signals transmitted from the ground broadcasting stations BC1, BC2,
and BC3 is detected, and the phase control signal for making the
phase difference zero is multiplexed by CDM and transmitted to each
of the ground broadcasting stations BC1, BC2, and BC3 as sources.
Each of the ground broadcasting stations BC1, BC2, and BC3 controls
the spreading code generation start timing for each channel in
accordance with the phase difference information sent from the
geostationary satellite SAT, thereby delaying the transmission
timing of the CDM broadcasting signal to be transmitted from the
self apparatus.
[0174] Therefore, the ground broadcasting stations BC1, BC2, and
BC3 start transmitting the CDM broadcasting signals at different
timings. For example, as shown in FIG. 10A, the ground broadcasting
station BC2 starts transmitting a CDM broadcasting signal in which
channels CH11 to CH1n are multiplexed. Next, at a time point
delayed from the transmission start point of the ground
broadcasting station BC2 by TD21, the ground broadcasting station
BC1 starts transmitting a CDM broadcasting signal in which channels
CH21 to CH2n are multiplexed. Subsequently, at a time point delayed
from the transmission start point of the ground broadcasting
station BC2 by TD23, the ground broadcasting station BC3 starts
transmitting a CDM broadcasting signal in which channels CH31 to
CH3n are multiplexed.
[0175] The delay amounts of the transmission timings of the CDM
broadcasting signals are set on the basis of the phase control
signals sent from the geostationary satellite SAT such that the
relative correlation values between the CDM broadcasting signals
transmitted from the ground broadcasting stations BC1, BC2, and BC3
become zero on the geostationary satellite SAT, as described
previously. For this reason, the CDM broadcasting signals
transmitted from the ground broadcasting stations BC1, BC2, and BC3
are received by the geostationary satellite SAT while making the
relative phase differences zero, as shown in FIG. 10B.
[0176] The broadcasting receiver receives CDM broadcasting signals
with spreading codes synchronized between the ground broadcasting
stations BC1, BC2, and BC3. Thus, once spreading code
synchronization is established for a CDM broadcasting signal
transmitted from one of the ground broadcasting stations, the
broadcasting signal from a desired ground broadcasting station can
be separated and reconstructed only by switching the spreading code
without newly establishing spreading code synchronization for the
CDM broadcasting signals from the remaining ground broadcasting
stations. Therefore, when the reception channel is to be switched
from the CDM broadcasting signal transmitted from the ground
broadcasting station BC1 to the CDM broadcasting signal transmitted
from the different ground broadcasting station BC2, switching can
be quickly performed at a high response speed.
[0177] Under the phase control of this embodiment, spreading code
synchronization between a plurality of channels transmitted from
one ground broadcasting station is also established on the
geostationary satellite SAT. Hence, even when the broadcasting
receiver MS is to switch the channel between the plurality of
channels transmitted from one ground broadcasting station, the
channel can be switched in a very short time at a high response
speed only by switching the spreading code to a corresponding
one.
[0178] As another embodiment of the present invention, the
broadcasting receiver may be carried by a high-speed mobile such as
an aircraft.
[0179] Generally, to receive a radio signal from the geostationary
satellite SAT on an aircraft, a doppler shift in reception
frequency occurs in the broadcasting receiver MS on the aircraft
because of the large relative speed between the geostationary
satellite SAT and the aircraft. In the conventional system using
FDM or TDM, the bandwidth per channel is as narrow as about 10 KHz.
A doppler shift of about several KHz makes it very difficult to
receive a desired channel. Therefore, the receiver carried by
aircraft, which is used in the conventional system using FDM or
TDM, requires various measures for correcting doppler shift,
resulting in a bulky apparatus.
[0180] However, in the satellite broadcasting system employing CDM
as in the present invention, the broadcasting signal of each
channel is spread in a wide band of, e.g., 25 MHz by spectrum
spreading. Consequently, even when a doppler shift is generated in
this state to shift the reception frequency by about several KHz,
the shift amount in the frequency band (25 MHz) of the channel is
very small, so the influence of the doppler shift can be neglected.
For this reason, according to this embodiment, the broadcasting
receiver used on an ground automobile or the like can be directly
carried and used on an aircraft, and the aircraft-carried-type
broadcasting receiver can be made much smaller and more inexpensive
than the conventional apparatus.
[0181] The broadcasting receiver used in the CDM satellite
broadcasting system of the present invention can also be carried by
a high-speed mobile such as the Shinkansen. In this case as well,
high-quality reception can be performed using a compact apparatus
while neglecting the influence of a doppler shift.
[0182] In addition, when the broadcasting receiver is carried by a
train, so-called diversity reception can be employed using the
length of the train such that reception antennas are set on cars
separated from each other, and reception signals from the antennas
are synthesized. This arrangement allows higher-quality
reception.
[0183] The present invention is not limited to the above
embodiments, and various changes and modifications can be made for
the procedure of setting phase synchronization between spreading
codes, contents of the processing, or the arrangements of the
ground broadcasting station, the geostationary satellite, and the
broadcasting receiver.
[0184] As has been described above in the first to sixth
embodiments, according to the first aspect of the present
invention, the spreading code phase relationship between the
broadcasting signals of channels code-division-multiplexed by a
multiplex means is set in a predetermined state by a
synchronization means. Alternatively, the phase difference between
the spreading codes of the channel signals of a multiplexed
broadcasting signal obtained by a multiplex means is detected by a
phase difference detection means, and information representing the
phase difference between the spreading codes, which is detected by
the phase difference detection means, is supplied to the
broadcasting receiver by a notification means. With this
arrangement, a satellite broadcasting system allowing the
broadcasting receiver to quickly switch the channels of the
multiplexed broadcasting signals at a high response speed can be
provided.
[0185] The second aspect of the present invention will be described
next throughout the seventh to ninth embodiments.
[0186] FIG. 11 is a view showing the schematic arrangement of a
satellite broadcasting system according to the seventh to ninth
embodiments of the present invention. This satellite broadcasting
system includes a plurality of ground broadcasting stations BC1 and
BC2 and a broadcasting satellite SAT. Each of the ground
broadcasting stations BC1 and BC2 transmits a program signal
prepared and edited by a broadcaster to the broadcasting satellite
SAT through a Ka- or Ku-band uplink transmission channel. The
broadcasting satellite SAT is managed by a satellite tracking
control station STCC to keep a predetermined position on the
geostationary orbit above the equator.
[0187] As shown in FIG. 12, the broadcasting satellite SAT is
constructed by attaching, to a satellite main body 21, solar cell
panels 22 and 23 serving as power sources, a Ka- or Ku-band antenna
24, and an S-band antenna 25. The Ka- or Ku-band antenna 24
includes a reflecting mirror 241 having a diameter of, e.g., 2.5-m
class, and a primary radiator 242. The S-band antenna 25 includes a
reflecting mirror 251 having a diameter of, e.g., 8- to 15-m class,
and a primary radiator group 252.
[0188] A broadcasting signal transmitted from the ground
broadcasting station BC1 or BC2 is received by the Ka- or Ku-band
antenna 24, demodulated and amplified by a signal processing unit
assembled in the satellite main body 21, and converted into a
signal in the S-band. The converted broadcasting signal is
transmitted from the S-band antenna 25 to a service area through an
S-band downlink transmission channel.
[0189] In the service area, a fixed station set, e.g., in an office
or at home, or a mobile station MS such as an
automobile-carried-type receiver or a portable terminal device
receives the broadcasting signal from the broadcasting satellite
SAT, as shown in FIG. 11.
[0190] In the S-band downlink transmission channel, a plurality of
channels, a maximum of 900 channels having a transmission rate of,
e.g., 64 to 256 kbps/channel are multiplexed using only code
division multiplex or both code division multiplex and time
division multiplex or frequency division multiplex. To transmit a
video signal using a channel, MPEG4 (Moving Picture Expert Group 4)
is used as a video coding method.
[0191] (Seventh Embodiment)
[0192] FIG. 13 is a view showing the arrangement of a satellite
broadcasting receiver according to the seventh embodiment of the
present invention. This satellite broadcasting receiver is used in
the satellite broadcasting system shown in FIG. 11.
[0193] As shown in FIG. 13, the satellite broadcasting receiver of
this embodiment includes two antennas 211 and 212, a signal
synthesizer 213, a RAKE receiver 214, an audio/video separation
circuit section 215, an audio decoder 216, a loudspeaker 217, a
video decoder 218, a liquid crystal display (LCD) 219, and a
control section 220.
[0194] Each of the two antennas 211 and 212 receives a radio wave
arriving through the downlink transmission channel and generates a
corresponding electrical signal (transmission signal). The antennas
211 and 212 are preferably rod antennas and separated from each
other as far as possible.
[0195] The transmission signals obtained by the antennas 211 and
212 are synthesized by the signal synthesizer 213, and the
synthesized signal is supplied to the RAKE receiver 214. The
transmission signal after synthesis by the signal synthesizer 213
is sequentially subjected to known processing such as
down-conversion to an IF or a baseband frequency, conversion into a
digital signal, spectrum despreading in a plurality of systems,
integration in a plurality of systems over one symbol period,
synthesis of the integration results of the plurality of systems,
deinterleave processing, Viterbi decoding, or error correction
decoding, thereby obtaining reception data.
[0196] The reception data obtained by the RAKE receiver 214 is
supplied to the audio/video separation circuit section 215 and
separated into audio data and video data. The audio data is decoded
and converted into analog data by the audio decoder 216. The audio
data is converted into an audio signal and supplied to the
loudspeaker 217, so the audio signal is amplified and output from
the loudspeaker 217. The video data is decoded by the video decoder
218 using, e.g., MPEG4 and supplied to the liquid crystal display
219, so a corresponding image is displayed on the liquid crystal
display 219.
[0197] Tuning control for the RAKE receiver 214 and separation
control for the audio/video separation circuit section 215 are
performed by the control section 220 on the basis of a
predetermined control program.
[0198] FIG. 14 is a perspective view showing an example of the set
state of the antennas 211 and 212 on a mobile.
[0199] In FIG. 14, the antennas 211 and 212 are respectively set
near the left corner on the front side and near the right corner on
the rear side of a mobile 221 (an automobile in FIG. 14). Since the
automobile has an almost rectangular shape when viewed from the
upper side, the antennas 211 and 212 are set near diagonal points
of the rectangle, respectively. The antennas 211 and 212 are offset
from each other in the moving direction of the mobile 221
(direction indicated by an arrow A in FIG. 14) and in a direction
perpendicular to the moving direction (direction indicated by an
arrow B in FIG. 14).
[0200] With this arrangement, unless an obstacle 222 is present
between the mobile 221 carrying the satellite broadcasting receiver
of this embodiment and the broadcasting satellite SAT, radio waves
from the broadcasting satellite SAT can be received by both the
antennas 211 and 212, as shown in FIG. 15A.
[0201] At this time, a transmission signal is obtained by each of
the antennas 211 and 212, though the two transmission signals may
have a phase difference.
[0202] However, since the transmission signals obtained by the
antennas 211 and 212 are synthesized by the signal synthesizer 213
and the synthesized signal is supplied to the RAKE receiver 214,
the transmission signals obtained by the antennas 211 and 212 are
used, in the RAKE receiver 214, for RAKE reception as different
transmission signals arriving through different paths, i.e., used
for reception at high S/N ratio using the path diversity effect.
That is, the signal synthesizer 213 performs not processing of
phase-matching the transmission signals obtained by the antennas
211 and 212 but simple synthesis.
[0203] Assume that the mobile 221 in the state shown in FIG. 15A
moves in the moving direction shown in FIG. 15A and assumes a state
shown in FIG. 15B. The radio wave which is to reach the antenna 211
is shielded by the obstacle 222, so the antenna 211 cannot receive
the radio wave.
[0204] In this state, however, the radio wave which is to reach the
antenna 212 is not shielded by the obstacle 222. Since the antenna
212 can receive the radio wave, the reception operation is
continuously performed.
[0205] The mobile 221 in the state shown in FIG. 15B further moves
in the moving direction shown in FIG. 15B, and the radio wave which
is to reach the antenna 212 is shielded by the obstacle 222 to
disable radio wave reception by the antenna 212, as shown in FIG.
15C. Even in this case, as far as the width of the obstacle 222 is
smaller than the distance between the antenna 211 and the antenna
212 along the moving direction of the mobile 221, the radio wave
which is to reach the antenna 211 is not influenced by the obstacle
222 even when the radio wave which is to reach the antenna 212 is
shielded by the obstacle 222. Therefore, as shown in FIG. 15C, the
antenna 211 can receive the radio wave, and the reception operation
is continuously performed.
[0206] Assume that the obstacle 222 is present only partially above
the direction perpendicular to the moving direction of the mobile
221, as shown in FIGS. 16A and 16B. In this situation, even when
the radio wave which is to reach one antenna is shielded by the
obstacle 222, the radio wave reaches the other antenna, so the
reception operation is continuously performed.
[0207] In this state, even when the obstacle 222 extends along the
moving direction of the mobile 221 over a length larger than the
distance between the antenna 211 and the antenna 212 along the
moving direction of the mobile 221, the reception operation is
continuously performed.
[0208] As far as the width of the obstacle 222 is smaller than the
distance between the antenna 211 and the antenna 212 along the
moving direction of the mobile 221, or the obstacle 222 is present
only partially above the direction perpendicular to the moving
direction of the mobile 221, the radio wave can always be received
even when the mobile 221 passes under the obstacle 222, and no hit
takes place.
[0209] Even when the width of the obstacle 222 is larger than the
distance between the antenna 211 and the antenna 212, the hit time
can be shortened because the time when both the antenna 211 and the
antenna 212 cannot receive the radio waves is shortened.
[0210] The satellite broadcasting receiver of this embodiment can
be modified by inserting low-noise amplifiers 223 and 224 between
the antennas 211 and 212 and the signal synthesizer 213, as shown
in FIG. 17, such that the transmission signals can be
low-noise-amplified and then synthesized by the signal synthesizer
213.
[0211] A space diversity system for performing reception using a
plurality of antennas, as in this embodiment, is known. However,
the known space diversity system aims to reduce the influence of
fading due to multipath transmission and is unnecessary for the
system of this embodiment using multipath transmission. The
arrangement as a characteristic feature of this embodiment may
appear to be similar to the known space diversity system. However,
this embodiment allows reception at a high S/N ratio by positively
using the multipath signal, so the influence of fading due to
multipath transmission is not reduced at all. This means that the
arrangement of this embodiment is achieved on the basis of a
technical concept different from that of the space diversity
system.
[0212] (Eighth Embodiment)
[0213] FIG. 18 is a view showing the arrangement of a satellite
broadcasting receiver according to the eighth embodiment of the
present invention. The same reference numerals as in FIG. 13 denote
the same parts in FIG. 18, and a detailed description thereof will
be omitted.
[0214] This satellite broadcasting receiver is used in the
satellite broadcasting-system shown in FIG. 11.
[0215] As shown in FIG. 18, the satellite broadcasting receiver of
this embodiment includes an antenna 211, a RAKE receiver 214, an
audio/video separation circuit section 215, an audio decoder 216, a
loudspeaker 217, a video decoder 218, a liquid crystal display 219,
a control section 220, a signal buffer 225, a hit determinator 226,
and a signal lost portion compensation circuit 227.
[0216] The signal buffer 225 stores and holds reception data
obtained by the RAKE receiver 214 for a predetermined time and then
supplies it to the audio/video separation circuit section 215. The
signal buffer 225 also serves as a work field for reception data
processing by the signal lost portion compensation circuit 227.
[0217] The hit determinator 226 monitors the operation condition
(e.g., the output condition of reception data) of the RAKE receiver
214 and detects a hit. Upon detecting a hit, the hit determinator
226 notifies the signal lost portion compensation circuit 227 of
it.
[0218] The signal lost portion compensation circuit 227 performs
processing of compensating the reception data (lost portion) when
the hit determinator 226 detects a hit.
[0219] The operation of the satellite broadcasting receiver having
the above arrangement will be described next.
[0220] If a radio wave sent from a broadcasting satellite SAT
normally reaches the antenna 211, the reception data is normally
extracted, by the RAKE receiver 214, from the transmission signal
obtained by the antenna 211. The reception data obtained by the
RAKE receiver 214 is stored and held by the signal buffer 225 and
sequentially supplied to the audio/video separation circuit section
215 every time a predetermined time has elapsed. If the radio wave
normally continuously reaches the antenna 211, no hit is detected
by the hit determinator 226, and the signal lost portion
compensation circuit 227 does not perform any processing for the
reception data stored in the signal buffer 225. Therefore, the
reception data is simply delayed by the buffer 225 for a
predetermined time.
[0221] Assume that a mobile carrying the satellite broadcasting
receiver of this embodiment moves, and an obstacle enters between
the broadcasting satellite SAT and the antenna 211. The radio wave
sent from the broadcasting satellite SAT is shielded by the
obstacle and prevented from reaching the antenna 211. At this time,
no transmission signal is supplied to the RAKE receiver 214
anymore, and the reception data output from the RAKE receiver 214
indicates no-signal state.
[0222] The hit determinator 226 detects a hit and notifies the
signal lost portion compensation circuit 227 of it. In response to
this, the signal lost portion compensation circuit 227 generates
compensation data for the lost portion by, e.g., copying or
estimating the data on the basis of predetermined data (e.g., data
of a portion having a high correlation with the lost portion)
around the lost portion in the reception data of the normal
portion, which is stored and held by the signal buffer 225. The
signal lost portion compensation circuit 227 writes the generated
compensation data in the signal buffer 225 to compensate for the
lost portion.
[0223] As described above, according to this embodiment, even when
the radio wave is shielded by an obstacle to generate a hit, the
lost portion of the reception data due to the hit is compensated
for on the basis of the reception data around the normally received
portion, so reception data without any lost portion is generated.
With this arrangement, degradation in reception quality can be
minimized.
[0224] (Ninth Embodiment)
[0225] FIG. 19 is a view showing the arrangement of a satellite
broadcasting system according to the ninth embodiment of the
present invention. The same reference numerals as in FIGS. 13 and
18 denote the same parts in FIG. 19, and a detailed description
thereof will be omitted.
[0226] The overall arrangement of this satellite broadcasting
system is the same as that of the satellite broadcasting system
shown in FIG. 11. FIG. 19 shows the arrangements of one of
satellite broadcasting receivers 2100 carried by mobile stations MS
in FIG. 11 and one of satellite broadcasting apparatuses 2200 set
in broadcasting stations BC in FIG. 11.
[0227] As shown in FIG. 19, the satellite broadcasting receiver
2100 of this embodiment includes an antenna 211, an audio/video
separation circuit section 215, an audio decoder 216, a loudspeaker
217, a video decoder 218, a liquid crystal display 219, a control
section 220, a RAKE receiver 228, a signal buffer 229, a signal
lost portion compensation circuit 230, a hit determinator 231, a
retransmission request processing section 232, a transmitter 233,
and an antenna 234.
[0228] A transmission signal obtained by the antenna 211 is
subjected, in the RAKE receiver 228, to the same reception
processing as that in the RAKE receiver 214 of the seventh
embodiment to obtain reception data. However, the RAKE receiver 228
extracts reception data associated with an arbitrary one of
broadcasting channels Bch, and parallelly, extracts reception data
associated with a predetermined retransmission channel Rch. The
reception data associated with the arbitrary one of the
broadcasting channels Bch is supplied to the signal buffer 229. The
reception data associated with the retransmission channel Rch is
supplied to the signal lost portion compensation circuit 230.
[0229] The reception data associated with the broadcasting channel
Bch is stored and held by the signal buffer 229 for a predetermined
time, i.e., delayed for a predetermined time, and then supplied to
the audio/video separation circuit section 215. The reception data
associated with the retransmission channel Rch is used by the
signal lost portion compensation circuit 230 to compensate for the
lost portion.
[0230] The signal lost portion compensation circuit 230 performs
processing of compensating the reception data (lost portion) using
the reception data associated with the retransmission channel Rch
when the hit determinator 231 detects a hit.
[0231] The hit determinator 231 monitors the operation condition
(e.g., the output condition of the reception data associated with
the broadcasting channel Bch) of the RAKE receiver 228 and detects
a hit. Upon detecting a hit, the hit determinator 231 notifies the
signal lost portion compensation circuit 230 and the retransmission
request processing section 232 of it.
[0232] When the hit determinator 231 detects a hit, the
retransmission request processing section 232 generates
retransmission request data for requesting retransmission of the
lost portion. The retransmission request data generated by the
retransmission request processing section 232 is converted into a
predetermined transmission signal to be radio-transmitted by the
transmitter 233, and then, sent from the antenna 234 to the
satellite broadcasting apparatus 2200 through a request channel
Dch.
[0233] The satellite broadcasting apparatus 2200 of this embodiment
includes a transmitter 235, a memory section 236, a retransmission
processing section 237, antennas 238 and 239, and a receiver
240.
[0234] In the satellite broadcasting apparatus 2200, transmission
data generated by a transmission data generation section (not
shown) or the like is supplied to the transmitter 235 and
simultaneously supplied to the memory section 236 and stored and
held as transmission data which has already been transmitted.
[0235] The transmission data is subjected, in the transmitter 235,
to processing such as error correction coding, convolution coding,
interleave processing, spectrum spreading processing, conversion
into an analog signal, up-conversion to a frequency for the
broadcasting channel Bch, or power amplification, and then
transmitted from the antenna 238 to the satellite broadcasting
receiver 2100 via the broadcasting satellite SAT.
[0236] When the transmission signal transmitted through the request
channel Dch is supplied to the receiver 240 via the antenna 239,
the transmission signal is received by the receiver 240, and
retransmission request data is reconstructed. The retransmission
request data is supplied to the retransmission processing section
237. The retransmission processing section 237 extracts the
transmission data of a portion represented by the retransmission
request data from the memory section 236, generates retransmission
data containing the transmission data, and supplies the
retransmission data to the transmitter 235.
[0237] The retransmission data is subjected, in the transmitter
235, to processing such as error correction coding, convolution
coding, interleave processing, spectrum spreading processing,
conversion into an analog signal, up-conversion to a frequency for
the retransmission channel Rch, or power amplification, and then
transmitted from the antenna 238 to the satellite broadcasting
receiver 2100 via the broadcasting satellite SAT.
[0238] The operation of the satellite broadcasting system having
the above arrangement will be described next.
[0239] If a radio wave sent from the broadcasting satellite SAT
normally reaches the antenna 211, the reception data is normally
extracted, by the RAKE receiver 228, from the transmission signal
obtained by the antenna 211. The reception data associated with the
broadcasting channel Bch and obtained by the RAKE receiver 228 is
stored and held by the signal buffer 229 and sequentially supplied
to the audio/video separation circuit section 215 every time a
predetermined time has elapsed. If the radio wave normally
continuously reaches the antenna 211, no hit is detected by the hit
determinator 231, and the signal lost portion compensation circuit
230 does not perform any processing for the reception data stored
in the signal buffer 229. Therefore, the reception data associated
with the broadcasting channel Bch is simply delayed by the signal
buffer 229 for a predetermined time.
[0240] In this state, the retransmission request processing section
232 does not generate retransmission request data. When all the
remaining satellite broadcasting receivers are in the
above-described normal state, no transmission signal is transmitted
through the request channel Dch. Hence, no retransmission request
data is obtained by the receiver 240, and no retransmission request
data is supplied to the retransmission processing section 237. As a
result, no retransmission data is generated and output by the
retransmission processing section 237.
[0241] Assume that the mobile carrying the satellite broadcasting
receiver 2100 of this embodiment moves, and an obstacle enters
between the broadcasting satellite SAT and the antenna 211. The
radio wave sent from the broadcasting satellite SAT is shielded by
the obstacle and prevented from reaching the antenna 211. At this
time, no transmission signal is supplied to the RAKE receiver 228
anymore, and the reception data output from the RAKE receiver 228
indicates no-signal state.
[0242] The hit determinator 231 detects a hit and notifies the
signal lost portion compensation circuit 230 and the retransmission
request processing section 232 of it.
[0243] In response to this, the retransmission request processing
section 232 generates retransmission request data for requesting
retransmission of the transmission data of the lost portion due to
the hit. The retransmission request data reaches the retransmission
processing section 237 through the transmitter 233, the antenna
234, the request channel Dch, the antenna 239, and the receiver
240.
[0244] Upon receiving the retransmission request data, the
retransmission processing section 237 extracts the transmission
data of the portion requested by the retransmission request data
from the memory section 236 and generates retransmission data
containing the transmission data. The retransmission data reaches
the signal lost portion compensation circuit 230 through the
transmitter 235, the antenna 238, the retransmission channel Rch,
the antenna 211, and the RAKE receiver 228. In response to this,
the signal lost portion compensation circuit 230 writes the
retransmission data in the signal buffer 229 to compensate for the
lost portion.
[0245] As described above, according to this embodiment, even when
the radio wave is shielded by an obstacle to generate a hit, the
satellite broadcasting apparatus 2200 retransmits the transmission
data of the lost portion generated in the reception data due to the
hit, in response to the request from the satellite broadcasting
receiver 2100. The satellite broadcasting receiver 2100 compensates
for the lost portion using the retransmission data, thereby
generating reception data without any lost portion. With this
arrangement, degradation in reception quality can be minimized.
[0246] The present invention is not limited to the above
embodiments. For example, in the above embodiments, the present
invention is applied to a satellite broadcasting receiver or a
satellite broadcasting apparatus used for a satellite broadcasting
system. However, the present invention can also be applied to
another radio communication system.
[0247] In the seventh embodiment, spread spectrum modulation is
used as modulation for multipath transmission. However, the present
invention can also be applied to a radio communication apparatus
used in a system using another modulation scheme such as
multicarrier modulation used in OFDM (Orthogonal Frequency Division
Multiplex).
[0248] The seventh embodiment can also be applied when three or
more antennas are used.
[0249] In the seventh embodiment, the antenna 211 and the antenna
212 are respectively set near the left corner on the front side and
near the right corner on the rear side of the mobile 221. However,
the arrangement is not limited to this.
[0250] In the seventh embodiment, an automobile is exemplified as
the mobile 221. However, the radio receiver of the present
invention can also be carried by another mobile such as a train.
For a train, the antenna 211 and the antenna 212 are set at
diagonal positions of each car. Alternatively, the antennas may be
set at the head of the first car and at the end of the last
car.
[0251] The eighth or ninth embodiment can incorporate the
arrangement of the antennas 211 and 212 and the signal synthesizer
213 in the seventh embodiment.
[0252] Various changes and modifications can be made within the
spirit and scope of the present invention.
[0253] As has been described above in the seventh to ninth
embodiments, according to the second aspect of the present
invention, in a radio receiver used in a radio communication system
for radio-transmitting a transmission signal modulated by a
predetermined modulation scheme for multipath transmission using
not only a direct wave but also an indirect wave, a reception means
performs predetermined multipath reception processing for a
synthesis signal obtained by synthesizing, by a signal synthesis
means, signals obtained by a plurality of antennas spaced apart
from each other.
[0254] As another form, in a radio receiver used in a radio
communication system for radio-transmitting a predetermined
transmission signal, transmission data demodulated from the
radio-transmitted transmission signal by a reception means is
stored in a storage means at least for a predetermined time. A hit
in the transmission signal received by the reception means is
monitored by a hit detection means. Transmission data corresponding
to a transmission signal portion where a hit is detected is
compensated by a compensation means on the basis of the
transmission data stored in the storage means or using transmission
data demodulated from a transmission signal retransmitted by a
retransmission means in the radio broadcasting apparatus in
response to a retransmission request sent by a retransmission
request means.
[0255] With this arrangement, the influence of a hit due to an
obstacle can be minimized, and a satisfactory reception quality can
be obtained.
[0256] The third aspect of the present invention will be described
next throughout the 10th to 16th embodiments.
[0257] (10th Embodiment)
[0258] FIG. 20 is a schematic view showing a satellite broadcasting
system having a gap filler function according to the 10th
embodiment of the present invention.
[0259] This satellite broadcasting system includes a plurality of
ground broadcasting stations (VSAT) BC1 and BC2 or feeder link
stations, a geostationary satellite SAT1, and a satellite tracking
control station STCC.
[0260] Each of the ground broadcasting stations (VSAT) BC1 and BC2
or feeder link stations transmits program information prepared and
edited by a broadcaster to the geostationary satellite SAT1 through
an uplink transmission channel in the Ka band (26.5 to 40 GHz) or
the Ku band (12.5 to 18 GHz).
[0261] The geostationary satellite SAT1 has a Ka-band or Ku-band
antenna having a diameter of 2.5-m class and an S-band (e.g., 2.6
GHz) antenna having a diameter of 15-m class. A broadcasting signal
multiplexed and transmitted from one of the broadcasting stations
(VSAT) BC1 and BC2 or the feeder link stations is received and
amplified by the Ka- or Ku-band antenna and then converted into a
signal for the S band. The converted broadcasting signal is
transmitted from the S-band antenna to a service area through a
downlink transmission channel in the S band. The uplink
transmission antenna carried by the geostationary satellite SAT1
may have a diameter smaller than 2.5-m class. The S-band antenna
may also have a diameter of not 15-m class but 8-m class.
[0262] The satellite tracking control station STCC monitors and
controls the operation state of the geostationary satellite
SAT1.
[0263] In the service area, a broadcasting receiver (not shown)
stationarily set, e.g., in an office or at home or a movable
broadcasting receiver MS carried by an automobile or carried as a
portable device receives the broadcasting signal transmitted from
the geostationary satellite SAT1 to the S-band downlink
transmission channel in the S band. In the S-band downlink
transmission channel, a plurality of channels, a maximum of 900
channels having a transmission rate of 64 to 256 Kbps/channel are
multiplexed. To transmit a video signal using a channel, MPEG4
(moving picture experts group 4) is used as a video coding
method.
[0264] In the system of the 10th embodiment, a gap filler apparatus
GFa is set on, e.g., the rooftop of a high-rise building. The gap
filler apparatus GFa receives the broadcasting signal from the
geostationary satellite SAT1, amplifies it, and then retransmits
the received broadcasting signal to an area behind a building or
the like where the broadcasting signal from the geostationary
satellite SAT1 cannot be received while holding the same frequency.
The gap filler apparatus GFa has the following arrangement.
[0265] FIG. 21 is a block diagram showing the arrangement of the
gap filler apparatus GFa. A broadcasting signal transmitted from
the geostationary satellite SAT1 is received by a reception antenna
311 and input to an signal synthesizer 213. After only a
predetermined transmission band is selected by the input filter
312, the signal is amplified by a low-noise amplifier 313. The
amplified broadcasting signal is amplified by a power amplifier
314, limited to a predetermined transmission band by an output
filter 315, and then transmitted from a transmission antenna 316 to
a dead area such as an area behind a building where the direct wave
from the geostationary satellite SAT1 does not reach. As the output
antenna 316, a directional antenna is used to limit the
broadcasting signal transmission range to the dead area where the
direct wave from the geostationary satellite SAT1 cannot be
received.
[0266] With this arrangement, the broadcasting signal transmitted
from each of the ground broadcasting stations BC1 and BC2 or feeder
link stations is sent to the geostationary satellite SAT1 through
the Ka- or Ku-band uplink transmission channel, and then
transmitted from the geostationary satellite SAT1 to the service
area through the S-band downlink transmission channel and received
by a broadcasting receiver MS in the service area. Since the
geostationary satellite SAT1 has a large-diameter S-band antenna of
15-m class, and the S-band can hardly be influenced by rain
attenuation, each broadcasting receiver MS receives the
broadcasting signal with a sufficiently high reception field
strength. For this reason, the broadcasting receiver MS can receive
the broadcasting signal using a compact rod antenna or planar
antenna.
[0267] However, the broadcasting receiver MS in the dead area
behind a building where the direct wave from the geostationary
satellite SAT1 cannot be received cannot directly receive the
broadcasting signal. The broadcasting signal transmitted from the
geostationary satellite SAT1 is received by the gap filler
apparatus GFa and then repeated and transmitted to the dead area
behind the building. With this arrangement, the broadcasting
receiver MS behind the building can also receive the broadcasting
signal.
[0268] The broadcasting signal repeated and transmitted from the
gap filler apparatus GFa is set at the same frequency as that of
the broadcasting signal sent from the geostationary satellite SAT1.
For this reason, the broadcasting receiver MS behind a building can
receive the broadcasting signal from the gap filler apparatus GFa
without using any special receiver as far as it has a receiver for
receiving the broadcasting signal from the geostationary satellite
SAT1.
[0269] The gap filler apparatus GFa transmits the broadcasting
signal to the dead area behind a building while limiting the
broadcasting range by using the directional antenna. Even when the
signal transmitted from the gap filler apparatus GFa is set at the
same frequency as that of the signal sent from the geostationary
satellite SAT1, the transmission signal from the gap filler
apparatus GFa is prevented from interfering with the signal from
the geostationary satellite SAT1 around the dead area behind a
building. Thus, the broadcasting receiver MS can receive the
broadcasting signal at a high quality in any area.
[0270] (11th Embodiment)
[0271] Generally, when a radio signal is transmitted from a
geostationary satellite arranged on the geostationary orbit above
the equator, an obstacle such as a building on the ground shades
the radio wave on the north side. Paying attention to this point,
in the 11th embodiment of the present invention, in an area where a
number of buildings stand, a gap filler apparatus repeats and
transmits a broadcasting signal with directivity in the
east-and-west direction.
[0272] FIGS. 22 and 23 are views for explaining this embodiment. In
shopping or business quarters where buildings stand close together
along a street, a band-shaped dead area where a radio signal from a
geostationary satellite SAT1 cannot be directly received extends in
the east-and-west direction on the north side of the buildings, as
indicated by a hatched portion in FIG. 22.
[0273] In this embodiment, a gap filler apparatus GFb is set at,
e.g., a large intersection where the broadcasting signal from the
geostationary satellite SAT1 can be directly received. To set the
gap filler apparatus GFb, for example, a post 345 is planted on a
paved street, and the gap filler apparatus GFb is fixed on the post
345.
[0274] The gap filler apparatus GFb has a main body 342
accommodating transmission/reception circuit sections such as a
low-noise amplifier and a power amplifier. An antenna 341 for
receiving the broadcasting signal from the geostationary satellite
SAT is attached to the upper portion of the main body 342. In
addition, retransmission antennas 343 and 344 are attached to two
side surface portions of the main body 342, which oppose each
other. The retransmission antennas 343 and 344 are set such that a
retransmission radio signal is transmitted in the east-and-west
directions.
[0275] If an existing post such as a road sign post, a signal post,
or a utility pole planted on a sidewalk or the like can be used,
the gap filler apparatus GFb may be set on the existing post
without providing the dedicated post 345.
[0276] In this embodiment, the broadcasting signal sent from the
geostationary satellite SAT1 is received and amplified by the gap
filler apparatus GFb, and then transmitted from the repeater
antennas 343 and 344 with directivity in the east-and-west
directions as shown in FIGS. 22 and 23. Therefore, with a small
number of gap filler apparatuses, a gap area where the broadcasting
signal from the geostationary satellite SAT1 cannot be directly
received can be effectively covered.
[0277] The gap filler apparatus GFb is not limited to an
arrangement in which the satellite reception antenna 341 and the
retransmission antennas 343 and 344 are integrally attached to the
main body 342. For example, the main body 342 having the satellite
reception antenna 341 is set, e.g., on the rooftop of a building
where the signal from the geostationary satellite SAT1 can be more
reliably received. The repeater antennas 343 and 344 are attached
to a road sign post, a signal post, or a utility pole planted in an
intersection. The main body 342 and the retransmission antennas 343
and 344 are connected through a coaxial cable. With this
arrangement, although connection between the main body 342 and the
retransmission antennas 343 and 344 slightly becomes cumbersome, a
gap filler apparatus having high reception performance can be
provided. As the antennas 343 and 344, compact patch antennas can
be used.
[0278] To cover a band-shaped dead area in a wide range, a gap
filler apparatus GFc is set at a high position such as the rooftop
of a building, as shown in FIG. 24, and the signal is transmitted
from the rooftop to the dead area with directivity. FIG. 24 shows a
case wherein a dead area several ten km to several km wide is
covered with this arrangement.
[0279] Depending on the shape of the dead area, a gap filler
apparatus GFd may be set on a pylon or the like, as shown in FIG.
25, and a broadcasting signal may be repeated and transmitted from
the gap filler apparatus GFd using a non-directional antenna. With
this arrangement, a wide, circular dead area can be covered.
[0280] (12th Embodiment)
[0281] In the 12th embodiment of the present invention, a plurality
of channel signals to be transmitted from a ground broadcasting
station to a satellite are multiplexed by CDM (Code Division
Multiplex). A gap filler apparatus amplifies the multiplexed CDM
broadcasting signal arriving via the satellite, and repeats and
transmits it to a gap area behind a building or the like.
[0282] FIG. 26 is a block diagram showing the arrangement of a
transmission section in a ground broadcasting station BC1 or BC2.
Broadcasting signals of a plurality of programs (N programs in FIG.
26) edited by a circuit (not shown) are input to modulators 351 to
35n, respectively. The modulators 351 to 35n
spread-spectrum-modulate the broadcasting signals using different
spreading codes generated from spreading code generators 361 to
36n, respectively. The broadcasting signals
spread-spectrum-modulated by the modulators 351 to 35n are
synthesized into one multiplexed broadcasting signal by a
synthesizer 371 and input to a modulator 372. The modulator 372
further modulates the multiplexed broadcasting signal by digital
modulation such as QPSK or QAM. The modulated multiplexed
broadcasting signal is frequency-converted into a Ka- or Ku-band
radio signal by a transmitter 373. The radio signal is amplified to
a predetermined transmission power level and then transmitted from
an antenna 374 to the geostationary satellite.
[0283] The geostationary satellite frequency-converts the
CDM-multiplexed broadcasting signal transmitted from the ground
broadcasting station BC1 or BC2 or a feeder link station into an
S-band signal, amplifies it to a predetermined power level, and
then transmits it to a ground service area.
[0284] The gap filler apparatus receives the CDM-multiplexed
broadcasting signal transmitted from the geostationary satellite,
amplifies the reception signal to the transmission power level for
gap filler, and transmits it to a dead area.
[0285] A broadcasting receiver MS has the following arrangement.
FIG. 27 is a block diagram showing the arrangement of the
broadcasting receiver MS. In FIG. 27, the CDM-multiplexed
broadcasting signal transmitted from the geostationary satellite
and the gap filler apparatus is received by an antenna 321 and
input to a receiver 322. The receiver 322 receives and reconstructs
a broadcasting signal in the CDM-multiplexed broadcasting signal,
which corresponds to a channel designated by the user, by RAKE
reception, and the reconstructed reception signal is input to an
audio/video separation circuit section 323.
[0286] The audio/video separation circuit 323 separates the
reconstructed reception signal into audio data, video data, and
additional data such as text data. The separated received audio
data is input to an audio decoder 324. The received video signal is
input to a video decoder 326. The additional data is input to an
additional data decoder 328. The audio decoder 324 decodes the
received audio data to reconstruct the audio signal, and the audio
signal is amplified and output from a loudspeaker 325. The video
decoder 326 decodes the received video data by, e.g., MPEG4 and
supplies the decoded video signal to a liquid crystal display 327
and causes the liquid crystal display 327 to display the video
signal. The additional data decoder 328 decodes the additional data
such as text data and causes the liquid crystal display 327 to
display the decoded data together with the video signal.
[0287] The receiver 322 has the following arrangement. FIG. 28 is a
block diagram showing the arrangement of the receiver 322. The
CDM-multiplexed broadcasting signal arriving from the geostationary
satellite and the gap filler apparatus is down-converted from the
radio frequency into a baseband frequency by a radio circuit 328.
The received baseband signal is digitized by an analog/digital
converter (A/D) 329 at a predetermined sampling period and then
input to a search receiver 330 and three digital data demodulators
331, 332, and 333.
[0288] The search receiver 330 receives and demodulates a pilot
signal transmitted from the ground broadcasting station BC1 or BC2
and basically has the same arrangement as that of each of the
digital data demodulators 331, 332, and 333 to be described
below.
[0289] Each of the digital data demodulators 331, 332, and 333
demodulates a broadcasting signal of the CDM-multiplexed
broadcasting signal arriving from the geostationary satellite or
the CDM-multiplexed broadcasting signal arriving from the gap
filler apparatus, which corresponds to the channel designated by
the user, by RAKE reception.
[0290] More specifically, the digital data demodulators 331, 332,
and 333 generate unique clocks with reference to the sampling clock
of the A/D converter 329 and independently operate on the basis of
the unique clocks. Each digital data demodulator has an initial
capture section, a clock tracking section, and a data demodulation
section. The data demodulation sections respectively include phase
compensation sections 3311, 3321, and 3331, multipliers 3312, 3322,
and 3332, PN code generators 3313, 3323, and 3333, and an
accumulators 3314, 3324, and 3334.
[0291] The phase compensation sections 3311, 3321, and 3331 perform
phase compensation of the reception signal for path diversity. The
multipliers 3312, 3322, and 3332 multiply the reception signals
output from the phase compensation sections 3311, 3321, and 3331 by
PN codes corresponding to the designated channel, which are
generated from the PN code generators 3313, 3323, and 3333,
respectively, to despread the spectra of the reception signals. The
accumulators 3314, 3324, and 3334 integrate the reception signals
despread and output from the multipliers 3312, 3322, and 3332,
respectively. The integration outputs are input to a symbol
synthesizer 334.
[0292] The symbol synthesizer 334 synthesizes the integration
outputs of the reception signals, which are output from the digital
data demodulators 331, 332, and 333, to reconstruct the data
component, and supplies the reconstructed data component to the
audio/video separation circuit section 323 shown in FIG. 27.
[0293] A control section 335 has a microcomputer as a main control
section and has, as a control function associated with RAKE
reception, a path position detection means and a PN code generation
control means. The path position detection means detects, from the
pilot signal received by the search receiver 32, the path position
of the signal arriving from the geostationary satellite SAT and the
path position of the signal arriving from the gap filler apparatus.
The PN code generation control means calculates an optimum PN
address value on the basis of the path position detection result
and supplies the PN address value to the PN code generators 3313,
3323, and 3333 of the three digital data demodulators 331, 332, and
333. With this operation, the chip phases of the PN codes generated
from the PN code generators 3313, 3323, and 3333 are variably
controlled.
[0294] When the broadcasting receiver MS having the above
arrangement is used, the CDM-multiplexed broadcasting signal sent
from the geostationary satellite and the CDM-multiplexed
broadcasting signal retransmitted from the gap filler apparatus can
be received, reconstructed, and synthesized as if a multipath
signal were received. That is, the CDM-multiplexed broadcasting
signal sent from the geostationary satellite and the
CDM-multiplexed broadcasting signal repeated and transmitted from
the gap filler apparatus can be received by path diversity. For
this reason, even when the broadcasting receiver MS is positioned
in an area where both the CDM-multiplexed broadcasting signal from
the geostationary satellite and the signal repeated and transmitted
from the gap filler apparatus can be received, high-quality
reception can be performed without causing interference between the
two signals.
[0295] According to this embodiment, since interference between the
CDM-multiplexed broadcasting signal from the geostationary
satellite and the signal repeated and transmitted from the gap
filler apparatus due to the same frequency need not be taken into
consideration, the directivity of the signal to be retransmitted
from the gap filler apparatus need not be strictly adjusted, so the
gap filler apparatus can be easily set.
[0296] (13th Embodiment)
[0297] In the 13th embodiment of the present invention, two
geostationary satellites, i.e., a main satellite and a spare
satellite, are spaced apart by a predetermined distance in the same
geostationary orbit. Identical broadcasting signals are transmitted
from these geostationary satellites to a service area in
synchronism with each other. This arrangement allows even a
broadcasting receiver MS in an area where the broadcasting signal
from the main satellite cannot be received to receive the
broadcasting signal from the spare satellite.
[0298] FIG. 29 is a schematic view of a satellite broadcasting
system according to this embodiment. In FIG. 29, two geostationary
satellites SATa and SATb are placed in the geostationary orbit
while being spaced apart by a predetermined distance. One of the
geostationary satellites SATa and SATb functions as a main
satellite, and the other functions as a spare satellite. The spare
satellite does not stand by but transmits the same broadcasting
signal as that from the main satellite even while the main
satellite is normally functioning.
[0299] With this arrangement, the mobile station MS in an area
where a broadcasting signal RSa from the main satellite SATa cannot
be received because of a building, as shown in FIG. 26, can receive
a broadcasting signal RSb from the spare satellite SATb.
Conversely, the mobile station MS in an area where the broadcasting
signal RSb from the spare satellite SATb cannot be received can
receive the broadcasting signal RSa from the main satellite SATa.
Therefore, according to this embodiment, the gap area can be
eliminated without setting any gap filler apparatus on the ground.
In addition, in this embodiment, the gap filler effect is realized
by using an existing spare satellite. For this reason, no new
satellite need be launched, and the system can be realized at low
cost.
[0300] (14th Embodiment)
[0301] In the 14th embodiment of the present invention, a
broadcasting signal transmitted from a ground broadcasting station
or a feeder link station is frequency-converted, in a geostationary
satellite, into a first broadcasting signal for a broadcasting
receiver and a second broadcasting signal for a gap filler
apparatus, which have different frequencies, and transmitted. The
gap filler apparatus receives the second broadcasting signal,
converts it into a broadcasting signal having the same frequency as
that of the first broadcasting signal, and then repeats and
transmits the broadcasting signal to a dead area.
[0302] FIG. 30 is a schematic view of a satellite broadcasting
system according to this embodiment. FIG. 31 shows the arrangement
of a transponder of a geostationary satellite SAT2 of this system.
FIG. 32 shows the arrangement of a gap filler apparatus.
[0303] On the transponder of the geostationary satellite SAT2, a
Ku-band uplink broadcasting signal UL (frequency fua) transmitted
from a ground broadcasting station BC is received by a reception
antenna 381, amplified by a low-noise amplifier 382, and input to a
signal distributor 383. The signal distributor 383 distributes the
uplink broadcasting signal to two systems.
[0304] One of the broadcasting signals is frequency-converted into
an S-band radio frequency signal (frequency fs) by a first
frequency converter 384, amplified, by a first power amplifier 386,
to a transmission power level necessary for reception by the
broadcasting receiver of a fixed station or a mobile station MS,
and then transmitted from an S-band transmission antenna 388 to a
ground service area as a first downlink broadcasting signal
DLa.
[0305] On the other hand, the other of the distributed broadcasting
signals is frequency-converted into a Ku-band radio frequency
signal (frequency fub) by a second frequency converter 388,
amplified, by a second power amplifier 387, to a transmission power
level necessary for reception by a gap filler apparatus GFe, and
then transmitted from a Ku-band transmission antenna 389 as a
second downlink broadcasting signal DLb. Although both the second
downlink broadcasting signal DLb and the uplink broadcasting signal
UL are transmitted in the Ku band, they have different frequencies.
For example, the frequency fub of the second downlink broadcasting
signal DLb is set at 14 GHz, and the frequency fua of the uplink
broadcasting signal UL is set at 12 GHz.
[0306] In the gap filler apparatus GFe, the second broadcasting
signal DLb transmitted from the geostationary satellite SAT2 is
received by an antenna 391, amplified by a low-noise amplifier 392,
and input to a frequency converter 393. The frequency converter 393
frequency-converts the received second downlink broadcasting signal
into an S-band radio frequency signal (frequency fs), i.e., a radio
frequency signal having the same frequency as that of the first
downlink broadcasting signal DLa which is transmitted from the
geostationary satellite SAT2 for a broadcasting receiver. The
broadcasting signal frequency-converted into the S band is
amplified to a transmission power level corresponding to the size
of a gap filler cover area GE by a power amplifier 394, and then
transmitted from a transmission antenna 395 to the gap filler cover
area GE as a repeated broadcasting signal DLg.
[0307] With this arrangement, the frequency of the downlink
broadcasting signal DLb arriving from the geostationary satellite
SAT2 and that of the repeated broadcasting signal DLg transmitted
to the gap filler cover area GE are different. Therefore, the gap
filler apparatus GFe can easily prevent the transmitted repeated
broadcasting signal DLg from reaching the reception antenna,
thereby easily and properly realizing isolation between the input
and the output.
[0308] (15th Embodiment)
[0309] In the 15th embodiment of the present invention, a second
broadcasting signal having the same contents as those of an uplink
broadcasting signal transmitted from a ground broadcasting station
to a geostationary satellite is transmitted to a gap filler
apparatus through a ground network. On the basis of the second
broadcasting signal transmitted through the ground network, the gap
filler apparatus generates a repeated broadcasting signal which is
the same as a downlink broadcasting signal transmitted from the
geostationary satellite to a broadcasting receiver, and transmits
the repeated broadcasting signal to a dead area.
[0310] FIG. 33 is a block diagram showing the arrangement. A ground
broadcasting station (not shown) generates a second broadcasting
signal having the same contents as those of an uplink broadcasting
signal transmitted from the self station to a geostationary
satellite and a signal format for cable transmission, and transmits
the second broadcasting signal to a gap filler apparatus GFf
through a ground public network NW such as an ISDN network.
[0311] When the gap filler apparatus GFf receives the second
broadcasting signal from the ground broadcasting station with a
modem, a signal conversion device 3101 converts the signal format
of the second broadcasting signal from the format for cable
transmission to a signal format for satellite broadcasting. The
broadcasting signal for satellite transmission is
frequency-converted into an S-band radio frequency signal by a
frequency converter 3102, amplified to a transmission power level
corresponding to the size of the dead area by a power amplifier
3103, and transmitted from a transmission antenna 3104 to the dead
area behind a building or the like as a repeated broadcasting
signal.
[0312] With this arrangement, even when the gap filler apparatus
cannot be set at a place where the downlink broadcasting signal
from the geostationary satellite can be received, the broadcasting
signal can be properly broadcasted to the dead area.
[0313] The gap filler apparatus GFf may have not only the circuit
for receiving the broadcasting signal through the ground public
network NW and generating the repeated broadcasting signal but also
a circuit for receiving the downlink broadcasting signal from the
geostationary satellite and converting it into the repeated
broadcasting signal, as in FIG. 21 or 32. One of the broadcasting
signals generated by the above circuits may be selected in
accordance with the set condition of the gap filler apparatus and
transmitted to the dead area.
[0314] More specifically, as shown in FIG. 34, a mode wherein a
downlink broadcasting signal from a geostationary satellite SAT' is
received via an antenna 3105 and the receiver and a mode wherein
the broadcasting signal is received through the ground public
network NW is switched by a switching device SW.
[0315] A circuit for determining the reception quality of the
downlink broadcasting signal from the geostationary satellite may
be added. If this determination circuit determines that the
downlink broadcasting signal has been received at a predetermined
reception quality, the repeated broadcasting signal from the
geostationary satellite is selected and transmitted to the dead
area. If it is determined that the predetermined reception quality
is not obtained, the repeated broadcasting signal generated on the
basis of the second broadcasting signal transmitted through the
ground public network NW is selected and transmitted to the dead
area.
[0316] (16th Embodiment)
[0317] In the 16th embodiment of the present invention, a gap
filler apparatus has a function of generating monitor information
representing the operation state of the self apparatus and
transmitting the monitor information to a monitor center, and the
monitor center monitors the operation state of the gap filler
apparatus on the basis of the monitor information.
[0318] FIG. 35 shows the first arrangement example of a system
according to this embodiment. Referring to FIG. 35, a gap filler
apparatus GFg detects a factor representing the operation state of
the self apparatus, i.e., the reception level of a downlink
broadcasting signal or the transmission level of a repeated
broadcasting signal, at a predetermined time interval and stores it
in a memory as monitor information.
[0319] A monitor center MCa generates a monitor information
transmission request regularly or at an arbitrary timing and sends
the transmission request to the gap filler apparatus GFg through a
ground network NW. In response to this, the gap filler apparatus
GFg reads out the monitor information from the memory and transmits
it to the monitor center MCa through the ground network NW. At this
time, only the latest monitor information is transmitted to the
monitor center MCa. However, all pieces of monitor information
stored from the preceding transmission timing to the current
transmission timing may be transmitted.
[0320] The monitor center MCa collects pieces of monitor
information from a plurality of gap filler apparatuses in a service
area by polling and displays or prints the collected monitor
information. The monitor center MCa also determines on the basis of
the contents of monitor information whether the operation state of
the gap filler apparatus is normal and displays the determination
result.
[0321] With this arrangement, the operation state of each gap
filler apparatus GFg can be concentrically managed by the monitor
center MCa, so efficient maintenance is allowed. In addition, since
the pieces of monitor information are collected by polling, the
monitor information of a number of gap filler apparatuses can be
efficiently collected.
[0322] FIG. 36 shows the second arrangement example of the system
according to this embodiment. Referring to FIG. 36, each gap filler
apparatus GFh and a monitor center MCb are connected through a
satellite communication channel. Every time a monitor information
transmission request arrives from the monitor center MCb through
the satellite communication channel, the gap filler apparatus GFh
reads out monitor information from the memory, converts the monitor
information into a signal format for satellite communication, and
transmits it to the monitor center MCb through the satellite
communication channel.
[0323] With this arrangement, since the pieces of monitor
information can be collected from the gap filler apparatuses using
the satellite communication channel of an existing geostationary
satellite, the communication line using the ground network NW is
unnecessary.
[0324] In the above-described examples, the monitor information of
the gap filler apparatus GFg or GFh is collected by polling from
the monitor center MCa or MCb. In addition to the collection
function by polling, the gap filler apparatus GFg or GFh may have
an operation state self determination function. If an operation
error is detected, the gap filler apparatus GFg or GFh may call the
monitor center MCa or MCb and notify the monitor center MCa or MCb
of the monitor information associated with the error.
[0325] In this case, when an operation error occurs in the gap
filler apparatus, the monitor center can immediately detect it, so
quick restoration is possible.
[0326] If the gap filler apparatus GFg or GFh detects a reception
error of the broadcasting signal from the satellite, or an
operation error of the gap filler apparatus GFg or GFh itself
occurs, the gap filler apparatus may send a message to notify the
monitor center MCa or MCb of it and simultaneously transmit the
message to each broadcasting receiver in the dead area. As the
message to be sent to each broadcasting receiver, a text message or
a voice message, "reception condition from the satellite is poor at
the moment; please wait for restoration", is used.
[0327] FIG. 37 shows the third arrangement example of the system
according to this embodiment. Referring to FIG. 37, in generating a
repeated broadcasting signal on the basis of the downlink
broadcasting signal arriving from the geostationary satellite and
transmitting it, a gap filler apparatus GFi multiplexes monitor
information representing the operation state of the self apparatus
to the repeated broadcasting signal and transmits it to the dead
area. As a multiplex scheme, FDM or CDM can be used.
[0328] A monitor receiver MR is located at an arbitrary position in
the dead area, e.g., at a position corresponding to the edge of the
area. The monitor receiver MR may be of a handy type carried by
maintenance personnel or an automobile carried type or may be
stationarily set. The monitor receiver MR receives the repeated
broadcasting signal transmitted from the gap filler apparatus GFi
and separates and extracts monitor information and also detects the
reception level of the repeated broadcasting signal. The reception
level detection data is inserted into the monitor information, and
this monitor information is transmitted to a monitor center MCc
through a mobile communication network INW such as a cellular radio
telephone system or a PHS.
[0329] With this arrangement, the reception level detection data
actually measured by the monitor receiver MR can be transmitted to
the monitor center MCc together with the monitor information
generated by the gap filler apparatus. For this reason, the monitor
center MCc can determine not only the operation state of the gap
filler apparatus itself but also the conformity between the
transmission level and the actual reception level in the dead
area.
[0330] The present invention is not limited to the above
embodiments. For example, both the scheme of setting a gap filler
apparatus on the ground to cover the dead area and the scheme of
using two geostationary satellites to cover the dead area may be
simultaneously exploited, thereby covering an area which is not
covered with either scheme.
[0331] In each of the above embodiments, a satellite broadcasting
system using a geostationary satellite has been exemplified, and a
broadcasting signal sent from the geostationary satellite is
received by a gap filler apparatus and retransmitted to the
broadcasting receiver MS. However, the present invention is not
limited to this arrangement. In, e.g., an interactive satellite
broadcasting system, a signal transmitted from the broadcasting
receiver MS to a satellite may be repeated by a gap filler
apparatus and transmitted to the satellite.
[0332] In the above embodiments, a dead area behind a building is
covered. However, the present invention can also be applied to
cover a gap area formed due to another construction such as a pylon
or a natural object such as a mountain or a cliff.
[0333] The present invention can also be applied to cover an indoor
dead area. For example, a compact indoor gap filler apparatus
(repeater) is set at a position, e.g., at a window where a downlink
broadcasting signal from a satellite can be directly received. A
repeated broadcasting signal is transmitted indoors from this
repeater and received by a receiver. In this case, the receiver may
be connected to the repeater through a coaxial cable or the like,
and the received downlink broadcasting signal may be transmitted to
the receiver through the coaxial cable. The repeater may be set on
the rooftop or roof of a building or a house.
[0334] In addition, for the arrangement or set place of the gap
filler apparatus, the type or arrangement of the broadcasting
receiver MS, the type of satellite, or the type or transmission
scheme of signal to be transmitted from the satellite as well,
various changes and modifications can be made within the spirit and
scope of the present invention.
[0335] As has been described above in the 10th to 16th embodiments,
according to the third aspect of the present invention, a gap
filler apparatus is used. A broadcasting signal repeated by a
satellite is received by the gap filler apparatus. In the service
area, the received broadcasting signal is radio-transmitted to an
area where the broadcasting signal from the satellite cannot be
received, at the same frequency as that of the broadcasting signal
transmitted from the satellite. With this arrangement, in the dead
area behind a building or the like, where the radio signal cannot
be directly received, not only a fixed station but also the mobile
station MS can properly receive the signal. Consequently, a
satellite broadcasting system capable of realizing effective gap
filler at low cost and a gap filler apparatus therefor can be
provided.
[0336] The fourth aspect of the present invention will be described
next throughout the 17th embodiment.
[0337] (17th Embodiment)
[0338] FIG. 38 shows the schematic arrangement of a satellite
broadcasting system according to the 17th embodiment of the present
invention. The satellite broadcasting system includes a
transmission station 410 situated on the ground and a geostationary
satellite 430 placed in the geostationary orbit above the equator
while being attitude-controlled on the basis of an instruction
signal from a satellite control station 420.
[0339] FIG. 38 illustrates only one station as the transmission
station 410. However, a plurality of stations may be used.
[0340] The satellite control station 420 receives, with a reception
antenna 431, a channel signal such as a Ku-band broadcasting signal
transmitted from the transmission station 410 through an uplink
transmission channel, frequency-converts the channel signal into
the S band, and transmits the signal from a transmission antenna
432 having a diameter of, e.g., 8 m to a predetermined service area
on the ground through a downlink transmission channel. In the
service area, the channel signal transmitted from the geostationary
satellite 430 is received by a reception terminal 450 (FIG. 41) (to
be described later) such as a mobile reception terminal carried by
a mobile, a portable reception terminal, or a fixed reception
terminal set on a ground construction.
[0341] In the transmission station 410, for example, when programs
1 to N are input, programs 1 to N are input to multipliers 4101 to
410N, respectively, as shown in FIG. 39. Spreading codes
corresponding to selection numbers (so-called channel numbers) for
selecting the signals on the reception terminals are input from
spreading code generators 4111 to 411N to the multipliers 4101 to
410N, so the multipliers 4101 to 410N multiply programs 1 to N by
the spreading codes, respectively, and output the results to a
synthesizer 412.
[0342] The synthesizer 412 generates channel signals multiplexed by
known CDM (Code division multiplex) and outputs the signals to a
modulator 413. The modulator 413 performs, e.g., spread spectrum
modulation for the input channel signals and outputs the modulated
signals to a transmitter 414. The transmitter 414
frequency-converts the input channel signals to the Ku band such
that the central frequencies are set at F1 and F2 and transmits the
channel signals from an antenna 415 to the geostationary satellite
430 through the uplink transmission channel.
[0343] For example, when channel signals (CH1 to CH8) are to be
transmitted, the channel signals (CH1, CH3, CH5, CH7, and CH8) are
set at the center frequency F1 while the channel signals (CH2, CH4,
and CH6) are set at the center frequency F2, as shown in FIG.
40.
[0344] The reception antenna 431 of the geostationary satellite 430
is connected to a reception feeder element 433 to output the
received channel signals to the reception feeder element 433. The
reception feeder element 433 is connected to, e.g., a polarizer
434, so the input channel signals (CH1 to CH8) are
frequency-converted and output to the polarizer 434. The polarizer
434 is connected to a feeder link receiver 435, so the input
channel signals are set to be, e.g., circularly polarized waves and
output to the feeder link receiver 435.
[0345] The feeder link receiver 435 is connected to a band filter
436, so the input channel signals as circularly polarized waves are
frequency-converted into, e.g, the S band and output to the band
filter 436. The band filter 436 is connected to the input terminals
of first and second power amplifiers 437a and 437b. Of the input
channel signals, the channel signals having the center frequency F1
(CH1, CH3, CH5, CH7, and CH8) are output to the first power
amplifier 437a, and the channel signals having the center frequency
F2 (CH2, CH4, and CH6) are output to the second power amplifier
437b.
[0346] The first power amplifier 437a is connected to a
right-circular polarizer 438a, so the input channel signals (CH1,
CH3, CH5, CH7, and CH8) are power-amplified and output to the
right-circular polarizer 438a. The right-circular polarizer 438a is
connected to a transmission feeder element 439, so the input
channel signals (CH1, CH3, CH5, CH7, and CH8) are converted into
right-circularly polarized waves and output to the transmission
feeder element 439.
[0347] The second power amplifier 437b is connected to a
left-circular polarizer 428b, so the input channel signals (CH2,
CH4, and CH6) are power-amplified and output to the right-circular
polarizer 438b. The right-circular polarizer 438b is connected to
the transmission feeder element 439, so the input channel signals
(CH2, CH4, and CH6) are converted into left-circularly polarized
waves and output to the transmission feeder element 439.
[0348] The transmission feeder element 439 is connected to the
transmission antenna 432 to transmit the input channel signals
(CH1, CH3, CH5, CH7, and CH8) and channel signals (CH2, CH4, and
CH6) to a predetermined service area through the downlink
transmission channel.
[0349] On the other hand, the reception terminal 450 for receiving
the channel signals (CH1 to CH8) from the geostationary satellite
430 has a reception antenna 451 corresponding to the transmission
antenna 432 of the geostationary satellite 430, as shown in FIG.
41. The received channel signals (CH1 to CH8) are output to a
reception feeder element 452. The reception feeder element 452 is
connected to a right-circular polarizer 453a and a left-circular
polarizer 453b. The output terminals of the right-circular
polarizer 453a and the left-circular polarizer 453b are connected
to a receiver 455 through a switch 454.
[0350] A switching operation device (not shown) is connected to the
switch 454. When the user operates the switching operation device
(not shown) to select one of the right-circular polarizer 453a and
the left-circular polarizer 453b, a switching signal is input. The
switch 454 selects one of the right-circular polarizer 453a and the
left-circular polarizer 453b in accordance with the switching
signal to output the channel signals (CH1, CH3, CH5, CH7, and CH8)
input to the right-circular polarizer 453a or the channel signals
(CH2, CH4, and CH6) input to the left-circular polarizer 453b to
the receiver 455.
[0351] As shown in FIG. 42, the receiver 455 has a radio circuit
455a corresponding to the switch 454. The radio circuit 455a is
connected to a despread circuit 455c through a demodulator 455b.
With this arrangement, when the channel signals (CH1, CH3, CH5,
CH7, and CH8) or the channel signals (CH2, CH4, and CH6) are input,
the radio circuit 455a frequency-converts the channel signals and
outputs them to the demodulator 455b.
[0352] The demodulator 455b demodulates the input channel signals
(CH1, CH3, CH5, CH7, and CH8) or channel signals (CH2, CH4, and
CH6) and outputs them to the despread circuit 455c. The despread
circuit 455c is connected to a control circuit 455d for selecting a
channel, so the input channel signals (CH1, CH3, CH5, CH7, and CH8)
or channel signals (CH2, CH4, and CH6) are subjected to despreading
processing, separated on the basis of a channel set signal input to
the control circuit 455d, and output to, e.g., a display section
(not shown) on the output side.
[0353] The channel set signal is set by the user by switching,
e.g., a channel set operation device (not shown).
[0354] As described above, in the satellite broadcasting system, a
plurality of channel signals having different central frequencies
are transmitted in the Ku band from the transmission station 410 to
the geostationary satellite 430, classified in units of central
frequencies in the geostationary satellite 430, converted into
right- or left-circularly polarized waves, and transmitted to the
service area as S-band channel signals. By selecting a channel on
the reception terminal 450, a desired channel signal is
received.
[0355] The signal processing section of the geostationary satellite
430 is divided into a right-circularly polarized wave system and a
left-circularly polarized wave system, i.e., constructed using a
plurality of signal processing systems with low power efficiency.
Since the number of channels can be increased using the signal
processing systems with low power efficiency, the arrangement can
easily meet the requirement for increasing the number of
channels.
[0356] The channel signals (CH1 to CH8) are separated into
right-circularly polarized wave signals and left-circularly
polarized wave signals and transmitted. Only signals of waves
circularly polarized in the same direction act as signal
interference sources. The interference noise power can be reduced
relative to the number of channels. From this viewpoint as well,
the number of channels can be made as large as possible.
[0357] When channel signals (CH1 to CH8) multiplexed by CDM are
reversely polarized, channel signals other than channel signals
circularly polarized in the same direction (e.g., when channel
signals are right-circularly polarized, left-circularly polarized
channel signals) act as interference noise power. For this reason,
as the number of channel signals to be transmitted from the
geostationary satellite increases, the interference noise power
increases, so a necessary power ratio C/N can hardly be ensured.
However, as the characteristic feature of the present invention,
when the transmitted channel signals are reversely polarized, the
interference noise power can be reduced, as described above, so the
number of channels can be increased.
[0358] More specifically, when the antenna axial ratio of the
geostationary satellite 430 to the reception terminal is about 2
dB/3 dB, isolation of 10 dB or more can be ensured to the reversely
polarized waves. When both polarized waves are used, the
interference noise power can be reduced by 55%, as compared to use
of only one polarized wave. When a desired transmission power can
be ensured, the channel capacity can be set to be larger by about
1.8 times.
[0359] In the 17th embodiment, the channel signals are circularly
polarized to right- or left-circularly polarized waves. However,
the present invention is not limited to this. The channel signals
can be linearly polarized to vertically polarized waves or
horizontally polarized waves. With this arrangement, almost the
same effect as described above can be expected.
[0360] In the 17th embodiment, as the modulation method, the
signals are modulated using spreading codes and multiplexed by CDM.
However, the present invention is not limited to this, and various
modulation methods or multiplex methods can be applied.
[0361] As has been described above in the 17th embodiment,
according to the fourth aspect of the present invention, a
satellite broadcasting system capable of easily increasing the
number of channels and a reception terminal therefor can be
provided.
[0362] The fifth aspect of the present invention will be described
next throughout the 18th embodiment.
[0363] (18th Embodiment)
[0364] FIG. 43 shows the schematic arrangement of a satellite
broadcasting system according to the 18th embodiment of the present
invention. This satellite broadcasting system includes a plurality
of broadcasting stations BC1 and BC2 (including feeder link
stations), a geostationary satellite SAT, and a satellite tracking
control station STCC. Each of the broadcasting stations BC1 and BC2
transmits program information prepared and edited by a broadcaster
to the geostationary satellite SAT through an uplink transmission
channel in the Ka band (26.5 to 40 GHz) or Ku band (12.5 to 18
GHz). The geostationary satellite SAT is managed by the satellite
tracking control station STCC to keep a predetermined position on
the geostationary orbit above the equator.
[0365] The geostationary satellite SAT has an arrangement shown in
FIG. 44. In FIG. 44, reference numeral 511 denotes a satellite main
body. The satellite main body 511 has solar cell panels 5121 and
5122 serving as power sources, a Ka- or Ku-band antenna 513
including a reflecting mirror 5131 having a diameter of 2.5-m class
(or smaller) and a primary radiator 5132, and an S-band (e.g., 2.6
GHz) antenna 514 having a reflecting mirror 5141 having a diameter
of 8- to 15-m class and a primary radiator 5142.
[0366] A broadcasting signal multiplexed and transmitted from the
ground broadcasting station BC1 or BC2 is received by the Ka- or
Ku-band antenna 513, demodulated and amplified by a signal
processing unit (not shown) in the satellite main body 511, and
converted into an S-band signal. The converted broadcasting signal
is transmitted from the S-band antenna 514 to a service area
through an S-band downlink transmission channel.
[0367] In the service area, a fixed station set, e.g., in an office
or at home or a mobile station MS such as an
automobile-carried-type receiver or a portable terminal device
receives the broadcasting signal transmitted from the geostationary
satellite SAT.
[0368] In the S-band downlink transmission channel, a plurality of
channels, a maximum of 900 channels having a transmission rate of
64 to 256 Kbps/channel are multiplexed. To transmit a video signal
using a channel, MPEG4 (moving picture expert group 4) is used as a
video coding method.
[0369] As a technique of attaching the large antenna 514 of 8- to
15-m class to the satellite main body 511 and arranging it in the
space, e.g., an "extended antenna structure" in Japanese Patent
Application No. 1-245707, an "extended antenna" in Japanese Patent
Application No. 1-195704, an "antenna reflecting mirror" in
Japanese Patent Application No. 63-242004, or an "extended annular
body" in Japanese Patent Application No. 2-261204 can be used.
[0370] When a multibeam formation type radiator is used as the
primary radiator 5142 of the S-band antenna 514, the service area
can be divided into a plurality of areas, and transmission beams
can be independently formed. FIG. 45 shows a beam arrangement when
the service area is divided into four areas. In FIG. 45, #1 to #4
represent reception areas covered by different transmission
beams.
[0371] When the transmission antenna 514 has the multibeam
function, all channels of the satellite broadcasting can be made
available to the entire service area, and additionally, an
arbitrary channel can be assigned to an arbitrary transmission beam
by a signal processing unit in the satellite and broadcasted to
only a necessary area. This allows a flexible service.
[0372] FIGS. 46 and 47 show the arrangement of a portable receiver
usable in the satellite broadcasting system with the above
arrangement. FIG. 46 shows the outer appearance, and FIG. 47 shows
the internal circuit arrangement.
[0373] In FIG. 46, reference numeral 521 denotes a case. The case
521 has a rod antenna 522 for receiving an S-band satellite
broadcasting wave, an operation button 523 for performing receiving
or tuning, a liquid crystal display 524 for displaying the received
video signal, and a pair of loudspeakers (L and R) 525 for
amplifying the received audio signal.
[0374] In FIG. 47, a satellite broadcasting signal from the
geostationary satellite SAT, which is captured by the rod antenna
522, is tuned to and detected by a receiver 526 and supplied to an
audio/video separation circuit section 527. The audio/video
separation circuit section 527 separates the reception signal into
audio data and video data. The audio data is supplied to an audio
decoder 528, and the video data is supplied to a video decoder
529.
[0375] The rod antenna 522 generally has directivity in all-around
directions, as shown in FIG. 48A. In Japan, even a satellite
broadcasting wave from a direction of about 45.degree. can be
received at a sufficient gain. When an antenna AT whose reception
beam pattern has a tilt angle of about 30.degree. to 60.degree. is
used, as shown in FIG. 48B, the broadcasting wave from the
satellite SAT can be received at almost the maximum gain.
[0376] If the reception beam pattern of the antenna AT can be
directed in an arbitrary direction, and the antenna direction is
controlled to obtain the maximum reception level, an
automobile-carried-type antenna, e.g., can always receive the
broadcasting wave from the satellite SAT at the maximum gain even
when the automobile has a tilt.
[0377] The audio decoder 528 decodes the received audio data to
reconstruct the audio signal. The reconstructed audio signal is
amplified and output from the loudspeakers 525. The video decoder
529 decodes the received video data by, e.g., MPEG4 to reconstruct
the video signal. The video signal is displayed on the liquid
crystal display 524.
[0378] Tuning control of the receiver 526 and separation control of
the audio/video separation circuit section 527 are performed by a
control CPU circuit section 530 on the basis of a predetermined
control program.
[0379] With the above arrangement, the broadcasting signals
transmitted from the plurality of broadcasting stations BC1 and BC2
are sent to the geostationary satellite SAT through the Ka- or
Ku-band uplink transmission channel, transmitted from the
geostationary satellite SAT to the service area through the S-band
downlink transmission channel, and received by the fixed station
and the mobile stations MS in the service area.
[0380] Since the frequency bands of the uplink transmission channel
and the downlink transmission channel are different, fading does
not occur.
[0381] Since the geostationary satellite SAT has the S-band antenna
514 having a large diameter of 8- to 15-m class, each fixed station
or the mobile station MS can receive the broadcasting signal at a
sufficiently large field strength. For this reason, each fixed
station or the mobile station MS can easily receive the
broadcasting signal with a compact rod antenna or planar
antenna.
[0382] When a communication channel is inserted as one of channels
of the broadcasting signal to be transmitted from the broadcasting
station BC1 or BC2, control of signal processing contents in the
satellite and individual control of each receiver can be
performed.
[0383] In the 18th embodiment, a portable receiver has been
exemplified. An indoor or automobile-carried-type receiver can also
be realized by the same circuit arrangement. Especially, as the
portable or automobile-carried-type antenna, a rod antenna or a
planar antenna having non-directional characteristics in at least
all-around directions is used. In this case, since the receiver
itself need not be directed to the arrival direction of the
satellite broadcasting wave, handling of the receiver is greatly
facilitated.
[0384] The conventional digital broadcasting image complies with
the NTSC system as the ground analog image scheme for current
televisions or an HDTV system having a higher quality, so it
requires a very high transmission rate, i.e., a wide band. For
example, the number of horizontal pixels.times.the number of
vertical lines.times.frame frequency falls within the range of
720.times.576.times.30 to 1920.times.1152.times.60. Even an MPEG2
video compression standard for a satisfactory transmission
environment corresponding to these scheme requires a rate of 15 to
100 Mbps.
[0385] As the data rate increases, a larger broadcasting power is
required, and the transmission band per channel also broadens. This
decreases the number of broadcasting channels available in a given
band. For mobile broadcasting in a poor transmission environment,
the broadcasting power must be further increased.
[0386] In this system, to decrease the broadcasting power necessary
to broadcast image broadcasting to a mobile such as an automobile
and increase the number of broadcasting channels, MPEG4 as a
high-compression scheme is used. Since the coding scheme itself is
highly robust against transmission errors, MPEG4 has received a
great deal of attention as a compression scheme for mobile
communication (radio communication).
[0387] FIG. 49 shows the arrangement of an MPEG4 image transmission
apparatus applicable to the 18th embodiment. A natural image signal
photographed with a video camera 531 or an artificial image signal
formed by computer graphic is coded and compressed by an MPEG4
coding device 532 and transmitted from a transmitter 533 to the
geostationary satellite SAT. The transmission output is broadcasted
to a predetermined area via the geostationary satellite SAT and
received by the receiver having the arrangement shown in FIG.
47.
[0388] The transmission wave from the geostationary satellite SAT
is directly broadcasted to the receiver, repeated by a ground
repeating station, or-repeated by another communication satellite
or broadcasting satellite.
[0389] FIGS. 50A and 50B show an example of a broadcasting screen
of this system. In correspondence with the 3- to 12-inch display
screen size of a portable or automobile-carried-type mobile
terminal, the number of horizontal pixels.times.the number of
vertical lines of an image is set at 176.times.144 or
352.times.288, as shown in FIG. 50A, the frame frequency per second
is set at 15, as shown in FIG. 50B, and the transmission rate is
set at about 64 to 256 kbps.
[0390] When the screen size, the number of horizontal pixels and
the number of vertical lines of an image, and the frame frequency
are appropriately set for the portable or automobile-carried-type
mobile terminal, the broadcasting power necessary to broadcast
image broadcasting to a mobile such as an automobile is decreased,
and the number of broadcasting channels can be increased.
[0391] When MPEG4 is used to compress and code a video signal to be
used for satellite broadcasting, the video signal can be
reconstructed in accordance with the radio wave reception condition
at the reception site, the pay broadcasting subscription condition
of the receiver, or the function of the incorporated video
decoder.
[0392] The above-described satellite broadcasting system of the
present invention can meet the following requirements.
[0393] National broadcasting and local broadcasting can be
selected.
[0394] Even a handheld reception terminal (with mobility) can
sufficiently receive the broadcasting signal.
[0395] A transmission station can be realized with simple equipment
and have an interactive function.
[0396] By increasing not only the image quality but also the number
of channels, information services can be provided using dedicated
channels. For example, various auctions, lectures of private
schools or preparatory schools, music programs with CD quality,
news, weather forecasts, stock information, leisure information,
religious information, local programs, private broadcasting, real
estate/housing information, bargain information, TV shopping,
various hobbies, data broadcasting, and the like can be
realized.
[0397] As has been described above in the 18th embodiment,
according to the fifth aspect of the present invention, a satellite
broadcasting system allowing reception by a receiver equipped with
a simple antenna system meeting requirements for not only indoor
use but also use on a mobile or use as a portable device, and a
satellite broadcasting receiver therefor can be provided.
[0398] The sixth aspect of the present invention will be described
next throughout the 19th embodiment.
[0399] (19th Embodiment)
[0400] FIG. 51 shows the arrangement of a satellite broadcasting
receiver according to the 19th embodiment of the present
invention.
[0401] The satellite broadcasting receiver includes an antenna 61,
a reception section 62, a video output interface 63, a screen input
section 64, a microphone (M) 65, a running state detection section
66, a card storage section 67, a timer 68, a storage section 69,
and a control section 610.
[0402] A broadcasting signal in which a plurality of channels are
multiplexed by the geostationary satellite is received by the
antenna 61 and input to the reception section 62. The reception
section 62 demodulates, in the multiplexed broadcasting signal, the
broadcasting signal of a channel designated from the control
section 610 (to be described later), reconstructs it as a video
signal (video signal) and an audio signal (not shown), and inputs
them to the video output interface 63.
[0403] The video output interface 63 is a video output terminal
which can be connected to an automobile-carried-type liquid crystal
monitor or the like.
[0404] The screen input section 64 is a touch screen panel mounted
on the display screen of a monitor connected to the video output
interface 63 and is composed of a video-transmission-type
piezoelectric device. The user touches this input device with a
finger or the like to designate a display area on the monitor and
designate a reception channel for the satellite broadcasting
receiver. Information input from the screen input section 64 is
input to the control section 610.
[0405] The microphone 65 is mounted on, e.g., the sun visor or
dashboard in the car. The microphone 65 receives speech of the
driver, converts the received speech into an electrical signal, and
inputs the signal to the control section 610.
[0406] The running state detection section 66 is a sensor for
detecting the opening ratio of the accelerator, the steering wheel
position, and the braking force of the car. The running state
detection section 66 inputs the pieces of detected information to
the control section 610 and input a velocity pulse obtained from
the control section of the car to the control section 610 as
running speed information.
[0407] The card storage section 67 includes a card interface 671
and a memory card 672.
[0408] The card interface 671 is a card slot to which the memory
card 672 is electrically connected. The control section 610 and the
memory card 672 are connected through the card interface 671.
[0409] The memory card 672 is a card type storage medium
incorporating a semiconductor memory such as a flash memory.
Information of channels whose reception is authorized by the
satellite broadcaster, information of channels viewed by the user,
and the reception times are recorded on this storage medium. The
memory card 672 can be removed from the card interface 671, as
needed.
[0410] The timer 68 counts time and notifies the control section
610 of the current time.
[0411] The storage section 69 is a semiconductor storage medium
such as a RAM or a ROM and has a speech data storage area 69a and a
program data storage area 69b as well as an area for storing
various control programs of the control section 610, the ID number
of the self apparatus, and program data preset by the user.
[0412] The speech data storage area 69a is an area for storing
speech data (voiceprint data) for identifying a specific user, or
speech data and predetermined instruction data in correspondence
with each other to recognize user's speech data input from the
microphone 65 as the instruction data such as a reception channel
switching instruction. The speech data storage area 69a also stores
speech data input by the user in advance in correspondence with the
instruction data to improve the speech recognition accuracy of the
speech data.
[0413] The program data storage area 69b stores information of
channels which can be received by the satellite broadcasting
receiver in the form of a hierarchy for each category or genre, as
shown in FIG. 52.
[0414] Also, program information (reception channels) corresponding
to the estimation result of the fatigue state of the driver (to be
described later) is stored in the program data storage area 69b.
For example, a program for awakening the user, e.g., a program
which broadcasts cheerful music is set in advance assuming a case
wherein the user is estimated to be tired and sleepy.
[0415] The control section 610 systematically controls the
respective portions of the satellite broadcasting receiver and has
a control function of controlling the reception section 62 in
response to information input from the screen input section 64 or
time information from the timer 68 to switch the reception channel.
The control section 610 also has a specific user identification
means 610a, a speech recognition means 610b, a driver state
estimation means 610c, a channel control section 610d, and a view
data recording control means 610e.
[0416] The specific user identification means 610a controls to
receive the voiceprint data of a specific user from the microphone
65 in advance and record the data in the speech data storage area
69a. When the user is to execute a specific function (reception of
a specific channel, change of contents stored in the storage
section 69, or the like) of the satellite broadcasting receiver,
verification processing of comparing the user's speech data input
from the microphone 65 with the voiceprint data stored in the
speech data storage area 69a to determine whether the user is a
specific user is performed.
[0417] The speech recognition means 610b recognizes the user's
speech data input from the microphone 65 as predetermined
instruction data using the data stored in the speech data storage
area 69a.
[0418] The driver state estimation means 610c analyzes the driving
time or degradation in driving capability on the basis of various
data detected by the running state detection section 66 and
estimates the fatigue state of the driver.
[0419] The channel control section 610d controls reception channel
switching in response to an instruction which is speech-recognized
by the speech recognition means 610b, or controls reception channel
switching to receive a program stored in the program data storage
area 69b when the driver state estimation means 610c has estimated
that the driver is fatigued.
[0420] Channels which can be received under this channel control
are reception channels stored on the memory card 672. For reception
channels whose reception is authorized to a specific user,
verification processing by the specific user identification means
610a is performed prior to reception.
[0421] The view data recording control means 610e obtains data of a
channel received by the satellite broadcasting receiver and the
reception time on the basis of the time information from the timer
68 and controls to record these data on the memory card 672.
[0422] In the satellite broadcasting receiver having the above
arrangement, when the driver pronounces a desired channel number to
switch the reception channel, this speech is input from the
microphone 65 to the control section 610.
[0423] The speech recognition means 610b recognizes the speech. In
response to this recognition result, the channel control section
610d controls the reception section 62 to switch the reception
channel. In designating a reception channel, reception channels are
visually and hierarchically presented on the monitor in units of
categories or genres.
[0424] According to the satellite broadcasting receiver with the
above arrangement, the driver can easily switch the reception
channel by speech on the basis of the hierarchically presented
reception channel group. That is, the driver can switch the
reception channel without being distracted from driving.
[0425] In the satellite broadcasting receiver having the above
arrangement, the fatigue state of the driver is estimated by the
driver state estimation means 610c on the basis of information
detected by the running state detection section 66. The channel
control section 610d controls the reception section 62 on the basis
of the estimation result to switch the channel to a reception
channel which broadcasts, e.g., cheerful music.
[0426] According to the satellite broadcasting receiver with the
above arrangement, the fatigue state of the driver is estimated by
various sensors. If it is estimated that the driver is fatigued,
the channel is switched to a reception channel which contributes to
prevent driving asleep (awakens the driver) to awaken the driver,
thereby preventing a traffic accident.
[0427] In the satellite broadcasting receiver having the above
arrangement, the view data recording control means 610e records the
information of the received channel and the view time information
on the memory card 672 usable to charge for reception. For this
reason, the user can easily pay the reception fee, and the
broadcaster can collect audience rating data in collecting the
reception fee.
[0428] As has been described above in the 19th embodiment,
according to the sixth aspect of the present invention, when the
user wants to switch the reception channel, he/she designates the
channel by speech through the microphone. The speech recognition
means recognizes it, and the reception means receives the channel
speech-input by the user. Since the reception channel can be easily
switched by speech input, a satellite broadcasting receiver capable
of switching the reception channel without distracting the driver
from driving can be provided.
[0429] In the sixth aspect, the fatigue state of the driver is
detected on the basis of the moving state of the mobile, and a
channel according to the detection result is received. According to
the present invention, setting is made such that a channel for
preventing the driver from driving asleep is received when it is
estimated that the driver is fatigued. Therefore, a satellite
broadcasting receiver capable of awakening the driver to prevent a
traffic accident can be provided.
[0430] The present invention is not limited to the above
embodiments, and various changes and modifications can be made
within the spirit and scope of the present invention.
INDUSTRIAL APPLICABILITY
[0431] As has been described above, according to the satellite
broadcasting system of the present invention, the broadcasting
receiver can quickly switch the channels of received multiplexed
broadcasting signals at a high response speed, thereby improving
the convenience for a viewer.
[0432] According to the radio receiver, a radio broadcasting
system, and a radio broadcasting apparatus of the present
invention, the influence of hits due to obstacles can be minimized,
and a satisfactory reception quality can be obtained.
[0433] According to the satellite broadcasting system of the
present invention and the gap filler apparatus therefor, not only a
fixed station but also a mobile station in an area behind
buildings, where a radio signal from the satellite cannot be
directly received, can properly receive the radio signal without
preparing large-scale equipment, thereby realizing an inexpensive
and effective gap filler.
[0434] According to the satellite broadcasting system and the
reception terminal of the present invention, the number of channels
can be easily increased with a simple arrangement.
[0435] According to the satellite broadcasting system and the
satellite broadcasting receiver of the present invention, a signal
can be received by a receiver using a simple antenna system meeting
requirements for not only indoor use but also use on a mobile or
use as a portable device.
[0436] According to the satellite broadcasting receiver of the
present invention, the reception channel can be switched without
distracting the driver of a mobile from driving. In addition,
reception channel switching is controlled in accordance with the
fatigue state of the driver to prevent a traffic accident.
* * * * *