U.S. patent application number 09/730424 was filed with the patent office on 2001-06-07 for apparatus and method for controlling radiation of electric waves.
This patent application is currently assigned to NEC Corporation. Invention is credited to Katou, Hironori, Kawabata, Shuji, Kumagai, Hiroki.
Application Number | 20010002821 09/730424 |
Document ID | / |
Family ID | 18381604 |
Filed Date | 2001-06-07 |
United States Patent
Application |
20010002821 |
Kind Code |
A1 |
Katou, Hironori ; et
al. |
June 7, 2001 |
Apparatus and method for controlling radiation of electric
waves
Abstract
An electromagnetic wave radiation control apparatus includes an
antenna, a modulator, an amplifier, and a radiation control unit.
The modulator modulates a carrier wave based on a transmission
signal to output a modulated signal, wherein the modulator stops
the output of the modulated signal in response to a power off
command. The amplifier amplifies the modulated signal such that the
amplified signal is radiated as electromagnetic wave from the
antenna, when the modulated signal is outputted from the modulator.
The radiation control unit generates the power off command to the
modulator, when radiation of electromagnetic wave in a current
radiation direction of the antenna is inhibited, or when a level of
a reception signal by the antenna is equal to or lower than a
predetermined minimum level.
Inventors: |
Katou, Hironori; (Tokyo,
JP) ; Kawabata, Shuji; (Tokyo, JP) ; Kumagai,
Hiroki; (Tokyo, JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
NEC Corporation
|
Family ID: |
18381604 |
Appl. No.: |
09/730424 |
Filed: |
December 5, 2000 |
Current U.S.
Class: |
342/352 |
Current CPC
Class: |
H01Q 3/00 20130101; H04B
1/3838 20130101; H01Q 1/28 20130101 |
Class at
Publication: |
342/352 |
International
Class: |
H04B 007/185 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 6, 1999 |
JP |
346171/1999 |
Claims
What is claimed is:
1. An electromagnetic wave radiation control apparatus comprising:
an antenna; a modulator which modulates a carrier wave based on a
transmission signal to output a modulated signal, wherein said
modulator stops the output of said modulated signal in response to
a power off command; an amplifier which amplifies said modulated
signal such that said amplified signal is radiated as
electromagnetic wave from said antenna, when said modulated signal
is outputted from said modulator; and a radiation control unit
which generates said power off command to said modulator, when
radiation of electromagnetic wave in a current radiation direction
of said antenna is inhibited, or when a level of a reception signal
by said antenna is equal to or lower than a predetermined minimum
level.
2. The electromagnetic wave radiation control apparatus according
to claim 1, wherein said radiation control unit comprises: a data
processor which outputs said power off command in response to an
error signal; and a control unit which generates said error signal
to said data processor, when radiation of electromagnetic wave in
said current radiation direction of said antenna is inhibited, or
when said reception signal level by said antenna is equal to or
lower than the predetermined minimum level.
3. The electromagnetic wave radiation control apparatus according
to claim 2, wherein said control unit comprises: a blocking state
determining section which generates a blocking error signal when
radiation of electromagnetic wave in the current radiation
direction of said antenna is inhibited; a lock status determining
section which generates an unlock signal when said reception signal
level is equal to or lower than the predetermined minimum level;
and a logic circuit which generates said error signal based on said
blocking error signal and said unlock signal.
4. The electromagnetic wave radiation control apparatus according
to claim 1, wherein said radiation control unit generates a high
voltage power off command to said amplifier depending said
amplified signal in a state in which said power off command is
outputted, and said amplifier stops an operation thereof in
response to said high voltage power off command such that said
amplified signal is not outputted to said antenna.
5. The electromagnetic wave radiation control apparatus according
to claim 4, wherein said radiation control unit generates said high
voltage power off command to said amplifier, when the radiation of
electromagnetic wave in said current radiation direction of said
antenna is inhibited, and when said amplifier outputs said
amplified signal.
6. The electromagnetic wave radiation control apparatus according
to claim 4, wherein said radiation control unit comprises: a data
processor which outputs said power off command in response to an
error signal; and a control unit which generates said error signal
to said data processor, when radiation of electromagnetic wave in
said current radiation direction of said antenna is inhibited, or
when said reception signal level by said antenna is equal to or
lower than the predetermined minimum level, and said high voltage
power off command to said amplifier, when said amplified signal is
outputted from said amplifier in a state in which the radiation of
electromagnetic wave in said current radiation direction of said
antenna is inhibited.
7. The electromagnetic wave radiation control apparatus according
to claim 6, wherein said control unit comprises: a blocking state
determining section which generates a blocking error signal when
radiation of electromagnetic wave in the current radiation
direction of said antenna is inhibited, and said high voltage power
off command to said amplifier, when said amplified signal is
outputted from said amplifier in the state in which the radiation
of electromagnetic wave in said current radiation direction of said
antenna is inhibited; a lock status determining section which
generates an unlock signal when said reception signal level is
equal to or lower than the predetermined minimum level; and a logic
circuit which generates said error signal based on said blocking
error signal and said unlock signal.
8. A method of controlling radiation of electromagnetic wave in
which a spacecraft which includes an antenna, a modulator which
modulates a carrier wave based on a transmission signal to output a
modulated signal, and an amplifier which amplifies said modulated
signal such that said amplified signal is radiated as
electromagnetic wave from said antenna, when said modulated signal
is outputted from said modulator, comprising: (a) determining
whether radiation of electromagnetic wave in a current radiation
direction of said antenna is inhibited; (b) determining a level of
a reception signal by said antenna is equal to or lower than a
predetermined minimum level; and (c) generating a power off command
to said modulator such that said modulator stops the output of said
modulated signal to said amplifier, when the radiation of
electromagnetic wave in the current radiation direction of said
antenna is inhibited, or when said reception signal level is equal
to or lower than the predetermined minimum level.
9. The method according to claim 8, wherein said (c) generating
includes: (d) generating an error signal to said data processor,
when the radiation of electromagnetic wave in said current
radiation direction of said antenna is inhibited, or when said
reception signal level by said antenna is equal to or lower than
the predetermined minimum level; and (e) generating said power off
command in response to said error signal.
10. The method according to claim 9, wherein said (d) generating
includes: generating a blocking error signal when the radiation of
electromagnetic wave in the current radiation direction of said
antenna is inhibited; generating an unlock signal when said
reception signal level is equal to or lower than the predetermined
minimum level; and generating said error signal based on said
blocking error signal and said unlock signal.
11. The method according to claim 8, wherein said (c) generating
further includes: generating a high voltage power off command to
said amplifier such that said amplifier stops an operation thereof
in response to said high voltage power off command, when said
amplified signal is outputted from said amplifier in a state in
which said power off command can be generated.
12. The method according to claim 11, wherein said (c) generating
includes: generating said high voltage power off command to said
amplifier, when the radiation of electromagnetic wave in said
current radiation direction of said antenna is inhibited, and when
said amplifier outputs said amplified signal.
13. The method according to claim 11, wherein said (c) generating
includes: (f) generating an error signal to said data processor,
when radiation of electromagnetic wave in said current radiation
direction of said antenna is inhibited, or when said reception
signal level by said antenna is equal to or lower than the
predetermined minimum level, and said high voltage power off
command to said amplifier, when said amplified signal is outputted
from said amplifier in the state in which the radiation of
electromagnetic wave in said current radiation direction of said
antenna is inhibited; and (g) generating said power off command in
response to an error signal.
14. The method according to claim 13, wherein said (f) generating
includes: generating a blocking error signal when radiation of
electromagnetic wave in the current radiation direction of said
antenna is inhibited, and said high voltage power off command to
said amplifier, when said amplified signal is outputted from said
amplifier in the state in which the radiation of electromagnetic
wave in said current radiation direction of said antenna is
inhibited; generating an unlock signal when said reception signal
level is equal to or lower than the predetermined minimum level;
and generating said error signal based on said blocking error
signal and said unlock signal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus and method for
controlling the radiation of electromagnetic wave. More
particularly, the invention relates to a technique for preventing
the radiation of electromagnetic wave to a specific region.
[0003] 2. Description of the Related Art
[0004] High level safety needs to be secured in a spacecraft and a
manned space station, and it is demanded that the electromagnetic
wave emitted from an antenna on the spacecraft should have the
electric field strength of 100 V/m or less with respect to human.
However, the main lobe of each antenna is usually greater than 100
V/m. Therefore, various measures are taken to attain the safety
required. For example, mechanical stoppers of the antenna pointing
mechanism are attached for the windows of the manned spacecraft.
The following techniques are known for eliminating the influence of
the radiation of electromagnetic wave.
[0005] For example, in "Apparatus for Preventing Radiation Hazard"
disclosed in Japanese Laid Open Patent Application (JP-A-Heisei
9-257914), a reception antenna is provided at a place such as a
staying location of a human being where harmful microwave should be
not applied, to detect microwave. When the antenna receives the
microwave, the radiation of the microwave from a radar apparatus is
stopped, thereby protecting human being from the radiation of
microwave.
[0006] Also, in "Apparatus for Preventing Radiation Hazard"
disclosed in Japanese Laid Open Patent Application (JP-A-Heisei
11-83987), a means for detecting radiation of microwave to a
staying place of the human being is provided to monitor the
radiation of the microwave. When the microwave is detected, the
operation of only the radar apparatus as a radiation source is
stopped. If the microwave emitted from any external source is
detected, this fact is notified to the external source. In this
method, any radar apparatuses other than the radar apparatus which
erroneously radiates the microwaves are not stopped, though the
microwave are detrimental to man.
[0007] Further, Japanese Patent No. 2910619 discloses "System for
stopping Power Supply for Radio Transmission". The system is
applied to a radio communication system in which data is
transmitted in two ways between the first and second radio
communication apparatuses of the same structure, by use of signals
having a frequency higher than the microwave-band frequency. More
specifically, the first radio communication apparatus receives the
signal from the second radio communication apparatus and detects
the level of the signal. When the first radio communication
apparatus detects that the level of the signal received has
remained equal to or below a predetermined value and the state of
the low reception signal level continues longer than a
predetermined time, the power supply to the second radio
communication apparatus is interrupted. Thereafter, the power is
intermittently supplied to the second radio communication apparatus
for every prescribed period. At this time, when the level of the
reception signal exceeds a predetermined value, power is then
continuously supplied to the second radio communication apparatus.
Thus, in the bidirectional radio communication system in which
microwave or electromagnetic wave of shorter wavelength is used,
the transmission output of the radio communication apparatus can be
automatically stopped, when there is high possibility that people
are exposed to the electromagnetic wave. This protects human being
from the radiation of electromagnetic wave.
[0008] It should be noted that in "Aircraft Radar Apparatus"
disclosed in Japanese Laid Open Utility Model application
(JU-A-Showa 60-145378), while a aircraft stays on the ground, a
signal representing an EL angle of an antenna on the aircraft is
inputted into a radar apparatus. When the signal indicates that the
EL angle has become smaller than a preset value, the high power
radiation of the electromagnetic wave from the antenna is
suppressed. Hence, the ground staff can inspect and repair the
radar apparatus, without being influenced by the electromagnetic
wave.
[0009] Also, in "Mobile Communication Apparatus" disclosed in
Japanese Laid Open Patent Application (JP-A-Heisei 10-70504), the
mobile communication apparatus is composed of an antenna, a
tracking unit, a receiver, a transmitter, a handset, and a control
unit. The antenna receives and transmits electromagnetic wave. The
tracking unit directs the antenna to the coming electromagnetic
wave. The receiver demodulates the electromagnetic wave. The
transmitter modulates data to be transmitted into electromagnetic
wave. The handset displays data to the user and receives
instructions from the user. The control unit controls the tracking
unit, receiver, transmitter and handset. The control unit, which is
essential to the apparatus, is composed of measurement means,
display means, and hazard inferring means. These means quickly
solve reception troubles that may frequently take place in the
communication section provided in the mobile communication
apparatus.
[0010] As described above, mechanical stoppers are attached to the
windows of a spacecraft to attain the safety required in the
spacecraft. Whether or not electromagnetic wave from the antenna is
radiated to the other parts of the spacecraft, which are provided
with no stoppers, is determined by means of software control.
Therefore, various design requirements must be fulfilled to enhance
the safety in the spacecraft.
[0011] It should be noted that "Apparatus for Preventing Radiation
Hazard" disclosed in Japanese Laid Open Patent Application
(JP-A-Heisei 9-257914) and "Apparatus for Preventing Radiation
Hazard" disclosed Japanese Laid Open Patent Application
(JP-A-Heisei 11-83987) have an antenna for detecting
electromagnetic wave, which is specially provided. Consequently,
the apparatus is complex and the manufacturing cost of the
apparatus is high.
[0012] Also, in "System for Interrupting Power Supply to Radio
Transmitters" disclosed in Japanese Patent No. 2,910,619, whether
electromagnetic wave should be radiated or not is determined in
accordance with the level of a signal received by the antenna and
the period for which the signal remains at the level. Therefore, it
cannot be said that the safety is sufficient.
SUMMARY OF THE INVENTION
[0013] Therefore, an object of the present invention is to provide
an apparatus and method for controlling the radiation of
electromagnetic wave, which have a simple structure and is realized
at low cost.
[0014] Another object of the present invention is to provide an
apparatus and method for controlling the radiation of
electromagnetic wave, which can yet serve to accomplish sufficient
safety.
[0015] In order to achieve an aspect of the present invention, a
electromagnetic wave radiation control apparatus includes an
antenna, a modulator, an amplifier, and a radiation control unit.
The modulator modulates a carrier wave based on a transmission
signal to output a modulated signal, wherein the modulator stops
the output of the modulated signal in response to a power off
command. The amplifier amplifies the modulated signal such that the
amplified signal is radiated as electromagnetic wave from the
antenna, when the modulated signal is outputted from the modulator.
The radiation control unit generates the power off command to the
modulator, when radiation of electromagnetic wave in a current
radiation direction of the antenna is inhibited, or when a level of
a reception signal by the antenna is equal to or lower than a
predetermined minimum level.
[0016] Here, the radiation control unit includes a data processor
which outputs the power off command in response to an error signal,
and a control unit. The control unit generates the error signal to
the data processor, when radiation of electromagnetic wave in the
current radiation direction of the antenna is inhibited, or when
the reception signal level by the antenna is equal to or lower than
the predetermined minimum level. In this case, the control unit may
include a blocking state determining unit, a lock status
determining unit and a logic circuit. The blocking state
determining unit generates a blocking error signal when radiation
of electromagnetic wave in the current radiation direction of the
antenna is inhibited. The lock status determining unit generates an
unlock signal when the reception signal level is equal to or lower
than the predetermined minimum level. The logic circuit generates
the error signal based on the blocking error signal and the unlock
signal.
[0017] Also, the radiation control unit may further generate a high
voltage power off command to the amplifier, when the amplified
signal is outputted from the amplifier in a state in which the
power off command can be generated. The amplifier stops an
operation thereof in response to the high voltage power off command
such that the amplified signal is not outputted to the antenna. The
radiation control unit generates the high voltage power off command
to the amplifier, when the radiation of electromagnetic wave in the
current radiation direction of the antenna is inhibited, and when
the amplifier outputs the amplified signal. The radiation control
unit may include a data processor and a control unit. The data
processor outputs the power off command in response to an error
signal. The control unit generates the error signal to the data
processor, when radiation of electromagnetic wave in the current
radiation direction of the antenna is inhibited, or when the
reception signal level by the antenna is equal to or lower than the
predetermined minimum level, and the high voltage power off command
to the amplifier, when the amplified signal is outputted from the
amplifier in the state in which the radiation of electromagnetic
wave in said current radiation direction of said antenna is
inhibited. In this case, the control unit may include a blocking
state determining unit, a lock status determining unit and a logic
circuit. The blocking state determining unit generates a blocking
error signal when radiation of electromagnetic wave in the current
radiation direction of the antenna is inhibited, and the high
voltage power off command to the amplifier, when the amplified
signal is outputted from the amplifier in the state in which the
radiation of electromagnetic wave in said current radiation
direction of said antenna is inhibited. The lock status determining
unit generates an unlock signal when the reception signal level is
equal to or lower than the predetermined minimum level. The logic
circuit generates the error signal based on the blocking error
signal and the unlock signal.
[0018] Another aspect of the present invention is directed to a
method of controlling radiation of electromagnetic wave in which a
spacecraft which includes an antenna, a modulator which modulates a
carrier wave based on a transmission signal to output a modulated
signal, and an amplifier which amplifies the modulated signal such
that the amplified signal is radiated as electromagnetic wave from
the antenna, when the modulated signal is outputted from the
modulator. The method is attained by (a) determining whether
radiation of electromagnetic wave in a current radiation direction
of the antenna is inhibited; by (b) determining a level of a
reception signal by the antenna is equal to or lower than a
predetermined minimum level; and by (c) generating a power off
command to the modulator such that the modulator stops the output
of the modulated signal to the amplifier, when the radiation of
electromagnetic wave in the current radiation direction of the
antenna is inhibited, or when the reception signal level is equal
to or lower than the predetermined minimum level.
[0019] The (c) generating may be attained by (d) generating an
error signal to the data processor, when the radiation of
electromagnetic wave in the current radiation direction of the
antenna is inhibited, or when the reception signal level by the
antenna is equal to or lower than the predetermined minimum level;
and by (e) generating the power off command in response to the
error signal. In this case, the (d) generating may be attained by
generating a blocking error signal when the radiation of
electromagnetic wave in the current radiation direction of the
antenna is inhibited; by generating an unlock signal when the
reception signal level is equal to or lower than the predetermined
minimum level; and by generating the error signal based on the
blocking error signal and the unlock signal.
[0020] Also, the (c) generating may further includes: generating a
high voltage power off command to the amplifier such that the
amplifier stops an operation thereof in response to the high
voltage power off command, when the amplified signal is outputted
from the amplifier in a state in which the power off command can be
generated. In this case, the (c) generating may be attained by
generating the high voltage power off command to the amplifier,
when the radiation of electromagnetic wave in the current radiation
direction of the antenna is inhibited, and when the amplifier
outputs the amplified signal.
[0021] Also, the (c) generating may be attained (f) generating an
error signal to the data processor, when radiation of
electromagnetic wave in the current radiation direction of the
antenna is inhibited, or when the reception signal level by the
antenna is equal to or lower than the predetermined minimum level,
and the high voltage power off command to the amplifier, when the
amplified signal is outputted from the amplifier in the state in
which the radiation of electromagnetic wave in said current
radiation direction of the antenna is inhibited; and by (g)
generating the power off command in response to an error signal. In
this case, the (f) generating may be attained by generating a
blocking error signal when radiation of electromagnetic wave in the
current radiation direction of the antenna is inhibited, and the
high voltage power off command to the amplifier, when the amplified
signal is outputted from the amplifier in the state in which the
radiation of electromagnetic wave in said current radiation
direction of said antenna is inhibited; by generating an unlock
signal when the reception signal level is equal to or lower than
the predetermined minimum level; and by generating the error signal
based on the blocking error signal and the unlock signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a block diagram showing the structure of a
spacecraft to which a electromagnetic wave radiation controlling
apparatus according to an embodiment of the present invention;
[0023] FIG. 2 is a block diagram showing the detailed structure of
an antenna drive control unit shown in FIG. 1; and
[0024] FIGS. 3A to 3C, 4A to 4C, 5A to 5D, 6A to 6D and 7A to 7D
are timing charts showing the operation of the spacecraft to which
the electromagnetic wave radiation controlling apparatus according
to the embodiment of the present invention is applied.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Hereinafter, a electromagnetic wave radiation control
apparatus of the present invention will be described below in
detail with reference to the attached drawings. The electromagnetic
wave radiation control apparatus according to an embodiment of the
present invention is designed for use in a spacecraft. Nonetheless,
the invention is not limited to one for use in the spacecraft.
Rather, the present invention can be applied to an apparatus for
controlling the radiation of electromagnetic wave, which is
designed for use in facilities on the ground.
[0026] FIG. 1 is a block diagram of a spacecraft to which the
apparatus and method for controlling the radiation of
electromagnetic wave according to this invention are applied. To
state more correctly, FIG. 1 mainly shows the components which are
related to the control of the radiation of electromagnetic wave.
The spacecraft shown in FIG. 1 is a part of a space station that
includes a main body (not shown).
[0027] The spacecraft is composed of an antenna 1, a diplexer 2, a
low noise amplifier 3, a tracking receiver 4, an antenna drive
control unit 5, an antenna drive unit 6, a data processing unit 7,
a modulator 8, and a traveling wave tube amplifier (TWTA) 9. A
structure 10 is composed of structural components of the spacecraft
and space station.
[0028] The antenna 1 receives electromagnetic wave from a data
relay satellite and transmits electromagnetic wave to the data
relay satellite. The antenna drive unit 6 drives the antenna 1 to
turn and track the data relay satellite. The antenna 1 converts
electromagnetic wave S12 transmitted from the data relay satellite,
into a electromagnetic wave signal. The electromagnetic wave signal
is supplied to the diplexer 2. The diplexer 2 supplies a signal to
be transmitted, to the antenna 1. The antenna 1 converts the
transmission signal supplied from the diplexer 2 into
electromagnetic wave S11 to transmit to the data relay satellite.
It should be noted that the data relay satellite relays
electromagnetic wave between the spacecraft to the ground
station.
[0029] The diplexer 2 controls the transmitting operation from the
antenna 1 and the receiving operation by the antenna 1. The
diplexer 2 supplies a signal from the antenna 1 to the low noise
amplifier 3, and supplies a transmission signal from the TWTA 9 to
the antenna 1. The low noise amplifier 3 amplifies the signal
supplied from the diplexer 2 and supplies the same to the tracking
receiver 4, in order to achieve high sensitivity reception.
[0030] The tracking receiver 4 detects an error signal S13 from the
signal (sum-difference composite signal) supplied from the antenna
1 through the diplexer 2 and the low noise amplifier 3. The
detected error signal S13 is supplied to the antenna drive control
unit 5. Also, the tracking receiver 4 detects an AGC level of the
reception signal supplied from the antenna 1 via the diplexer 2 and
the low noise amplifier 3. The detected AGC level signal S14 is
supplied to the antenna drive control unit 5. The antenna drive
control unit 5 uses the error signal S13 and the AGC level signal
S14 to track the data relay satellite.
[0031] The antenna drive control unit 5 receives the following
signals, in addition to the error signal S13 and AGC level signal
S14 supplied from the tracking receiver 4. That is, an attitude
sensor data signal S15 is supplied to the antenna drive control
unit 5 from various attitude sensors provided on the spacecraft,
such as a solar sensor, an earth sensor, and a gyroscope. An
orbit/attitude/blocking data signal S16 is supplied to the antenna
drive control unit 5 from the main body of the space station. A
resolver signal S17 is supplied from the antenna drive unit 6 to
the antenna drive control unit 5.
[0032] The antenna drive control unit 5 carries out a calculation
process to direct the antenna 1 to the data relay satellite based
on the error signal S13, the attitude sensor data signal S15, the
orbit/attitude/blocking data signal S16 and the resolver signal
S17. Data obtained through the calculation process to drive the
antenna 1 to a direction, i.e., antenna direction control data is
supplied to the antenna drive unit 6 as a control signal S18. The
antenna drive unit 6 drives the antenna 1 to direct to the data
relay satellite in accordance with the control signal S18.
[0033] Also, the antenna drive control unit 5 generates a blocking
error signal S20 and a high voltage power off command S19 based on
the attitude sensor data S15, the orbit/attitude/blocking data
signal S16, the AGC level signal S14 and an output monitor signal
S35 of the TWTA 9 such that the operation of the TWTA 9 can be
turned off. The blocking error signal S20 is supplied to the data
processing unit 7 to stop the power supply to the modulator 8, and
the high voltage power off command S19 is supplied directly to the
TWTA 9 to stop the high voltage power supply to the TWTA 9.
[0034] Further, the antenna drive control unit 5 determines a lock
status based on the AGC level signal S14 supplied from the tracking
receiver 4. If the determination result indicates an unlock state
of the antenna 1, the antenna drive control unit 5 generates and
supplies the blocking error signal S20 to the data processing unit
7. The antenna drive control unit 5 will be described later in
greater detail.
[0035] The antenna drive unit 6 drives the antenna 1 in response to
the control signal S18 supplied from the antenna drive control unit
5. The antenna drive unit 6 generates the resolver signal S17 that
represents the current direction of the antenna 1. The resolver
signal S17 is supplied to the antenna drive control unit 5.
[0036] The data processing unit 7 generates a power off command S21
in response to the blocking error signal S20 supplied from the
antenna drive control unit 5. The power off command S21 is supplied
to the modulator 8.
[0037] The modulator 8 modulates carrier wave based on a data
signal to produce a electromagnetic wave signal S22. During the
modulation, various data to be transmitted from the spacecraft to
the data relay satellite are modulated on the carrier wave. The
electromagnetic wave signal S22 obtained through the modulator 8 is
supplied to the TWTA 9. The power supply to the modulator 8 is
turned off in accordance with the power off command S21 supplied
from the data processing unit 7.
[0038] The TWTA 9 amplifies the electromagnetic wave signal
supplied from the modulator 8 to supply to the antenna 1 and to
supply to the antenna drive control unit 5 as an output monitor
signal S35. Also, the power supply to the TWTA 9 is turned off in
accordance with the high voltage power off command S19 supplied
from the antenna drive control unit 5.
[0039] The structure 10 is composed of devices provided on the
space station such as solar cell paddles, radiators, and
assemblies, and prevents radiation and incidence of electromagnetic
wave from and to the antenna 1.
[0040] Next, the above antenna drive control unit 5 will be
described in detail with reference to the block diagram of FIG. 2.
As shown in FIG. 2, the antenna drive control unit 5 is composed of
a tracking error data processing section 23, an angle control loop
calculating section 24, an antenna direction calculating section
25, a resolver data processing section 26, a blocking state
determining section 27, a lock status determining section 28, and
an AND circuit 29.
[0041] The tracking error data processing section 23 generates
error data from the error signal S13 supplied from the tracking
receiver 4. The error data is supplied to the angle controlling
loop calculating section 24.
[0042] The resolver data processing section 26 generates resolver
data from the resolver signal S17 supplied from the antenna drive
unit 6. The resolver data is supplied to the angle control loop
calculating section 24, and the antenna direction calculating
section 25.
[0043] The antenna direction calculating section 25 calculates the
pointing direction of the antenna 1 to be directed based on the
attitude sensor data S15 supplied from the attitude sensors,
satellite orbit data S30, and spacecraft orbit data S31 which are
contained in the orbit/attitude/blocking data S16 supplied from the
main body of the space station. The antenna direction calculating
section 25 supplies the calculation result to the angle control
loop calculating section 24 and the blocking state determining
section 27 as an antenna pointing direction data S33.
[0044] The angle control loop calculating section 24 receives the
error data from the tracking error data processing section 23, the
antenna pointing direction data S33 from the antenna pointing
direction calculating section 25, the resolver data from the
resolver data processing section 26. The calculating section 24
generates a control signal S18 based on the above received data.
The control signal S18 is supplied to the antenna drive unit 6 as
described above.
[0045] The blocking state determining section 27 receives the
antenna pointing direction data S33 from the antenna pointing
direction calculating section 25, the radiation inhibited region
data S34 contained in the orbit/attitude/blocking data S16 from the
space station main body, and the output monitor signal S35
outputted from the TWTA 9. Based on the data S33, data S34 and
signal S35, the blocking state determining section 27 generates the
high voltage power off command S19 and a signal S41 that represents
existence or non-existence of a blocking error. The blocking error
means that a part of the structure 10 exists in the main lobe of
the antenna 1. The signal S41 is set to the logic level of "0" when
there is a blocking error, and the logic level of "1" when there is
no blocking error. The signal S41 is supplied to one input of the
AND circuit 29. The high voltage power off command S19 is supplied
to the TWTA 9, as described above.
[0046] The lock status determining section 28 determines whether
the antenna 1 is in the locked state or the unlocked state, based
on the AGC level signal S14 supplied from the tracking receiver 4.
The lock status determining section 28 generates a signal S40 that
represents the determination result. The signal S40 is set to the
logic level of "1" when the antenna 1 is in the unlocked state, and
the logic level of "0" when the antenna 1 is in the locked state.
The signal S40 is supplied to the other input of the AND circuit
29.
[0047] The AND circuit 29 calculates a logic product of the signals
S41 supplied from the blocking state determining section 27 and the
signal S40 supplied from the lock status determining section 28,
and supplies the calculation result as a blocking error signal S20
to the data processing unit 7. The blocking error signal S20 is set
to the inactive state of the logic level of "1", when the signal
S41 has the logic level of "1" to indicate that there is no
blocking error and when the signal S40 has the logic level of "1"
to indicate that the antenna 1 is in the unlocked state. In other
words, the blocking error signal S20 is set to the active state of
the logic level of "0", when the signal S41 has the logic level of
"0" to indicate that there is a blocking error, or the signal S40
has the logic level of "0" to indicate that the antenna 1 is in the
locked state.
[0048] The description will be made of the operation of the
electromagnetic wave radiation controlling apparatus in case where
the radiation of electromagnetic wave S11 from the antenna 1 should
be suppressed, in the spacecraft to which the electromagnetic wave
radiation controlling apparatus having the above structure is
applied. It is necessary to control the radiation of the
electromagnetic wave in the spacecraft having the complicated
structure 10 such as a space station such that the electromagnetic
wave is erroneously not radiated when there is the structure 10 in
the main lobe of the antenna 1.
[0049] To this end, the antenna drive control unit 5 allows the
antenna 1 to emit the electromagnetic wave S11 when the
determination result of the lock status which has been determined
based on the AGC level signal S14 supplied from the tracking
receiver 4 indicates the locked state, and when the structure 10 is
stayed outside the main lobe of the antenna 1 directing to the data
relay satellite.
[0050] To be more specific, the lock status determining section 28
of the antenna drive control unit 5 receives the AGC level signal
S14 from the tracking receiver 4. The lock status determining
section 28 determines whether the antenna 1 is in the locked state
or in the unlocked state, to generate the signal S40 indicative of
the determination result. The signal S40 is supplied to the AND
circuit 29. In this case, if the signal S40 has the logic level of
"0" to indicate that the antenna 1 is in the locked state, the AND
circuit 29 generates and supplies the blocking error signal S20
having the logic level of "0" to the data processing unit 7. The
data processing unit 7 generates and supplies the power off command
S21 to the modulator 8 in response to the blocking error signal
S20. Upon receipt of the power off command S21, the power supply to
the modulator 8 is stopped so that the modulator 8 turns off the
electromagnetic wave signals S22. As a result, the TWTA 9 has no
input at all to have no output from the TWTA 9, so that the
radiation of electromagnetic wave from antenna 1 is controlled to
be suppressed.
[0051] Also, the blocking state determining section 27 of the
antenna drive control unit 5 determines whether the structure 10
exists in the main lobe of the antenna 1 when the antenna 1 is
directed to the data relay satellite, namely, whether there is a
blocking error, based on the antenna pointing direction data S33
supplied from the antenna pointing direction calculating section 25
and the radiation inhibited region data S34 supplied from the space
station main body. The blocking state determining section 27
generates the signal S41 indicative of the determination result to
the AND circuit 29. In this case, if the signal S41 has the logic
level of "0" to indicate that there is the blocking error, the AND
circuit 29 generates and supplies the blocking error signal S20
having the logic level of "0" to the data processing unit 7. In
this way, the radiation of electromagnetic wave S11 from the
antenna 1 can be controlled to be suppressed as in the case where
the lock status indicates the locked state.
[0052] Through the above operation, the electromagnetic wave S11 is
emitted from the antenna 1 when the lock status determined based
the AGC level signal S14 supplied from the tracking receiver 4
indicates the unlocked state, and when the structure exists outside
the main lobe of the antenna 1 directed to the data relay
satellite. This helps to secure high safety.
[0053] The blocking state determining section 27 of the antenna
drive control unit 5 outputs the high voltage power off command S19
to the TWTA 9 when the output from the TWTA 9 has the logic level
of "0" to indicate that there is an blocking error, after the
blocking state determining section 27 has outputted the signal 41
having the logic level of "0". The high voltage power supply of the
TWTA 9 is turned off in response to the high voltage power off
command S19. As a result, the radiation of electromagnetic wave S11
from the antenna 1 is suppressed. Hence, the safety can be
enhanced, because the radiation of electromagnetic wave S11 from
the antenna 1 is suppressed even if the power supply of the
modulator 8 cannot be stopped due to some cause.
[0054] As mentioned above, the on/off control of the power supply
of the modulator 8 is primarily and the on/off control of the power
supply of the TWTA 9 is provided for back-up. This is because it is
necessary to provide some redundant means to control the radiation
of electromagnetic wave from the viewpoint of high safety, and the
number of times the power supply of the TWTA 9 can be turned on and
off is limited because of the characteristics of the TWTA 9.
[0055] Next, the description will be made of the operation of the
spacecraft to which the electromagnetic wave radiation controlling
apparatus according to the embodiment of the present invention is
applied, with reference to the timing charts of FIGS. 3A to 3C, 4A
to 4C, 5A to 5D, 6A to 6D, and 7A to 7D.
[0056] FIGS. 3A to 3C show the situation of the radiation of
electromagnetic wave when the data relay satellite is invisible
from the spacecraft and then becomes visible therefrom during the
normal operation, while the structure 10 is stayed outside the view
field of the antenna 1, and then changes into the invisible state.
In this case, when the state changes from the invisible state to
the visible state, the lock status of the tracking receiver 4
changes from the logic level of "0" to the logic level of "1". As a
result, the power supply of the modulator 8 is turned on in
response to the change of the lock status, whereby the antenna 1
starts emitting electromagnetic wave S11, as shown in FIG. 3C. When
the satellite becomes invisible thereafter, the lock status of the
tracking receiver 4 changes from the logic level of "1" to the
logic level of "0". At this time, the power supply of the modulator
8 is turned off, whereby the antenna 1 stops emitting
electromagnetic wave S11, as shown in FIG. 3C.
[0057] FIGS. 4A to 4C show the situation of the radiation of
electromagnetic wave when the data relay satellite is first in the
state invisible from the spacecraft and then changes to the state
visible therefrom during the normal operation, while the structure
10 enters the view field of the antenna 1, and then goes out the
view field. In this case, the lock status of the tracking receiver
4 changes from the logic level of "0" to the logic level of "1"
when the data relay satellite changes from the invisible state to
the visible state. Therefore, the power supply of the modulator 8
is turned on, whereby the antenna 1 starts emitting electromagnetic
wave S11, as shown in FIG. 4C. However, when the blocking error is
detected due to the existence of the structure 10 (obstacle) while
the power supply of the modulator 8 remains turned on, the power
supply of the modulator 8 is turned off in a short time (about one
second or less), so that the antenna 1 emits no electromagnetic
wave S11 at all, as shown in FIG. 4C.
[0058] FIGS. 5A to 5D show the situation of the radiation of
electromagnetic wave when the lock status of the tracking receiver
4 changes from the logic level of "1" to the logic level of "0" due
to some cause during the period during which any blocking error
caused due to the structure 10 is not detected after the data relay
satellite changes the state invisible from the spacecraft to the
state visible therefrom during the normal operation. In this case,
the power supply of the modulator 8 changes from the turned-on
state to the turned-off state in synchronism with the lock status,
so that the antenna 1 stops emitting electromagnetic wave S11, as
shown in FIG. 5D. This enhances the safety.
[0059] FIGS. 6A to 6D show the situation where the modulator 8 is
turned on due to some trouble in the state in which the data relay
satellite remains invisible from the spacecraft. In this case,
because the lock status of the tracking receiver 4 remains having
the logic level of "0", the antenna 1 emits no electromagnetic wave
S11, as shown in FIG. 6D.
[0060] FIGS. 7A to 7D show the situation that a trouble may occur
in the antenna drive unit 6. In this case, the antenna 1 on the
spacecraft cannot be directed to the data relay satellite.
Therefore, the lock status of the tracking receiver 4 has the logic
level of "0". Thus, the power supply of the modulator 8 cannot be
turned on, so that the antenna 1 emits no electromagnetic wave S11,
as shown in FIG. 7D. This also enhances the safety.
[0061] As has been described, the antenna radiation controlling
apparatus according to the embodiments of the present invention,
the determination result of the lock status obtained from the AGC
level signal S14 supplied from the tracking receiver 4 is used for
determination of whether or not the electromagnetic wave should be
radiated. Therefore, the following advantages can be obtained.
[0062] That is, the frequency used for the data relay satellite
falls within the Ka band (23 to 26 GHz). The antenna 1 on the
spacecraft cannot receive the electromagnetic wave S12 from the
data relay satellite as long as the structure 10 stays in the main
lobe of the spacecraft. Consequently, the AGC level signal S14
outputted from the tracking receiver 4 is reduced. The lock status
of the receiver 4 obtained from the AGC level signal S14 indicates
an unlocked state. Hence, the antenna drive control unit 5 supplies
the blocking error signal S20 to the data processing unit 7.
[0063] In this way, the data processing unit 7 generates the power
off command S21 in response to the blocking error signal S20, which
is supplied to the modulator 8. Upon receipt of the command S21,
the modulator 8 turns off the electromagnetic wave signal S22 as
its output, so that nothing is inputted to the TWTA 9. Therefore,
the antenna 1 stops emitting electromagnetic wave S11. Thus, no
electromagnetic wave is emitted while the structure 10 of the
spacecraft exists in the main lobe of the antenna 1.
[0064] More specifically, the radiation of electromagnetic wave is
controlled even if the following trouble is caused. For example,
when the resolver signal S17 supplied from the antenna drive unit 6
is erroneous, there is a case that the antenna 1 directs to the
structure 10. Even in this case, the antenna 1 does not emit
electromagnetic wave S11 at all, because the lock status obtained
from the AGC level signal S14 supplied from the tracking receiver 4
indicates that the antenna 1 is in the locked state.
[0065] Also, the high voltage power off command S19 is supplied to
the TWTA 9 so that the electromagnetic wave S11 emitted from the
antenna 1 may not be applied to the structure 10. There is a
possibility that the TWTA 9 cannot receive the high voltage power
off command S19 due to a trouble in the input circuit of the TWTA
9. In this case, the antenna 1 may inevitably be directed to the
structure 10. Even in this case, the radiation of electromagnetic
wave S11 from the antenna 1 can be controlled to be suppressed in
the same manner as described above.
[0066] Further, according to the electromagnetic wave radiation
controlling apparatus according to the embodiment of the present
invention, the detection of the structure 10 is made by means of an
ordinary antenna for transmitting and receiving data signals.
Therefore, no special antenna needs to be used to detect the
detection of the structure 10. This renders it easy and economical
to manufacture the electromagnetic wave radiation controlling
apparatus of the present invention.
* * * * *