U.S. patent application number 14/448895 was filed with the patent office on 2014-11-20 for directional diversity receive system.
The applicant listed for this patent is Troll Systems Corporation. Invention is credited to Jeff HOPKINS, Chris NOSKI, Julian SCOTT.
Application Number | 20140341325 14/448895 |
Document ID | / |
Family ID | 42117493 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140341325 |
Kind Code |
A1 |
SCOTT; Julian ; et
al. |
November 20, 2014 |
DIRECTIONAL DIVERSITY RECEIVE SYSTEM
Abstract
Embodiments disclosed herein relate to a directional diversity
receive system. The system may comprise a plurality of antennas
attached to and fixed with respect to a frame. The system may
further comprise a steerable antenna attached to and moveable with
respect to the frame. The system may be encapsulated by a cover and
may be configured for relocation as an integrated module.
Inventors: |
SCOTT; Julian; (Glendale,
CA) ; HOPKINS; Jeff; (Valencia, CA) ; NOSKI;
Chris; (Valencia, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Troll Systems Corporation |
Valencia |
CA |
US |
|
|
Family ID: |
42117493 |
Appl. No.: |
14/448895 |
Filed: |
July 31, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12605279 |
Oct 23, 2009 |
8816933 |
|
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14448895 |
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61107821 |
Oct 23, 2008 |
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Current U.S.
Class: |
375/347 |
Current CPC
Class: |
H01Q 1/1257 20130101;
H01Q 19/132 20130101; H04B 7/0808 20130101; H01Q 21/00 20130101;
H01Q 3/04 20130101; H04B 7/086 20130101; H04B 7/082 20130101; H01Q
21/20 20130101; H01Q 3/02 20130101 |
Class at
Publication: |
375/347 |
International
Class: |
H04B 7/08 20060101
H04B007/08 |
Claims
1. A system for receiving wireless signals, comprising: a plurality
of fixed antennas configured to provide spatial diversity when
receiving a wireless signal; a steerable antenna configured to
receive the wireless signal; and a controller in data communication
with the plurality of fixed antennas and the steerable antenna,
wherein the controller is configured to determine the robustness of
the received wireless signal at one or more of the plurality of
fixed antennas, and further configured to determine a fixed antenna
among the plurality of fixed antennas receiving the wireless signal
with the most robustness, wherein the steerable antenna is
configured to be steered in a direction approximately aligned with
a receiving direction of the fixed antenna receiving the wireless
signal with the most robustness.
2. The system of claim 1, wherein the steerable antenna comprises a
directional high gain antenna.
3. The system of claim 1, wherein the steerable antenna comprises a
parabolic antenna.
4. The system of claim 1, wherein the steerable antenna comprises a
yagi antenna.
5. The system of claim 1, wherein the plurality of fixed antennas
are configured to receive the wireless signal from any direction
within a 360 degree azimuth.
6. The system of claim 5, wherein the plurality of fixed antennas
are arranged to define a circumference, and are configured to
receive signals at least from a direction opposite that of an area
within the circumference.
7. The system of claim 6, wherein the plurality of fixed antennas
are approximately uniformly spaced about the circumference.
8. The system of claim 7, wherein the steerable antenna is located
in an area within the circumference.
9. The system of claim 1, wherein at least one of the plurality of
fixed antennas comprises one of a panel antenna, a slot antenna, or
a sector antenna.
10. The system of claim 1, further comprising a plurality of
demodulators, each demodulator being connected to a respective one
of the plurality of fixed antennas and the steerable antenna.
11. The system of claim 1, wherein the system is configured to
wirelessly receive digital video data.
12. A method of receiving wireless signals with an antenna system,
comprising: receiving a wireless signal at a plurality of fixed
antennas configured to provide spatial diversity when receiving the
wireless signal; determining the robustness of the received
wireless signal at one or more of the plurality of fixed antennas;
determining a fixed antenna among the plurality of fixed antennas
receiving the wireless signal with the most robustness; and
steering a steerable antenna in a direction approximately aligned
with a receiving direction of the fixed antenna receiving the
wireless signal with the most robustness.
13. The method of claim 12, wherein the steerable antenna comprises
a directional high gain antenna.
14. The method of claim 12, wherein the steerable antenna comprises
a parabolic antenna.
15. The method of claim 12, wherein the steerable antenna comprises
a yagi antenna.
16. The method of claim 12, wherein the plurality of fixed antennas
are configured to receive the wireless signal from any direction
within a 360 degree azimuth.
17. The method of claim 16, wherein the plurality of fixed antennas
are arranged to define a circumference, and are configured to
receive signals at least from a direction opposite that of an area
within the circumference.
18. The method of claim 17, wherein the plurality of fixed antennas
are approximately uniformly spaced about the circumference.
19. The method of claim 18, wherein the steerable antenna is
located in an area within the circumference.
20. The method of claim 12, wherein the wireless signal comprises
digital video data.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/605,279, filed Oct. 23, 2009, which claims
the benefit of U.S. Provisional Patent Application No. 61/107,821,
filed Oct. 23, 2008 Each of the above-referenced patent
applications is hereby incorporated by reference in its
entirety.
BACKGROUND
[0002] Embodiments disclosed herein relate to wireless transmit and
receive systems. More specifically, embodiments herein may relate
to a directional diversity receive system.
[0003] A traditional radio frequency (RF) link consists of both a
transmit and receive system. Such RF link may use the digital COFDM
(Coded Orthogonal Frequency Division Multiplexing)
modulation/demodulation schemes to transmit and/or receive audio,
encapsulated data, compressed video, or other information or data.
The transmit system takes the information and converts it into a
modulated RF signal using a transmitter and radiates that energy
into the air via an antenna. The receive system uses an antenna to
collect the RF energy and feed it to a receiver which then
demodulates the signal back into the original information.
[0004] Between the output of the transmit antenna and the input of
the receive antenna, the RF signal propagates through the air
getting attenuated and bounced off terrain, buildings, or water. As
received at the receive antenna, the signal typically should have
enough power (from the transmitter) and gain (from the receive
antenna) to overcome the attenuation due to the air and to satisfy
the threshold signal level required by the receiver. Attenuation
due to the air is dependent on a number of factors, such as
distance traveled, frequency of the signal (higher frequency
signals generally get attenuated more), and atmospheric conditions
(hot/cold and dry/wet air may all affect the attenuation). The
attenuation can be roughly calculated, but greater attenuation
called fading may occur under certain conditions. Such greater
attenuation must be accounted for when designing receive
systems.
[0005] In addition, the receive system may also receive none, some,
or all of the bounced signals, which is known as natural
multi-path. This natural multi-path presents multiple images of the
same signal at the receiver due to paths having varied lengths
which are taken by the bounced signals to get from the transmit
antenna to the receive antenna. In addition, the system may receive
other transmitted signals of the same, or similar, frequency and
power levels, known as unnatural multi-path. To receive a desired
signal, the system can preferably discriminate against and overcome
both forms of multi-path to demodulate the desired signal.
[0006] Problems further to those described above may also be
experienced when receiving a signal. For example, too much received
signal, be it a desired signal or signal from natural and/or
unnatural multi-path, can be a problem due to an input amplifier of
the receiver being driven into a non-linear region and causing
unrecoverable distortions of the desired signal.
[0007] A need exists for improved wireless communication systems
and methods, for example for use with the transmission and
reception of RF signals. More specifically, a need exists for
improved receive systems and methods of controlling those receive
systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a front view of an embodiment of a directional
diversity receive system.
[0009] FIG. 2 is a perspective view of the embodiment of the
diversity receive system of FIG. 1, and shows a partial
enclosure.
[0010] FIG. 3 is a perspective view of another embodiment of a
directional diversity receive system.
[0011] FIG. 4 is an overhead view of the embodiment of the
directional diversity receive system of FIG. 2.
[0012] FIG. 5 is a side view of the embodiment of the directional
diversity receive system of FIG. 2.
[0013] FIG. 6 is a front view of the embodiment of the directional
diversity receive system of FIG. 2.
[0014] FIG. 7 is another side view of the embodiment of the
directional diversity receive system of FIG. 2, and shows a full
enclosure.
[0015] FIG. 8 is a perspective view of an embodiment of a
directional diversity receive system.
[0016] FIG. 9 is an overhead view of the embodiment of the
directional diversity receive system of FIG. 8.
[0017] FIG. 10 is a front view of the embodiment of the directional
diversity receive system of FIG. 8.
[0018] FIG. 11 is a side view of the embodiment of the directional
diversity receive system of FIG. 8.
[0019] FIG. 12 is a functional block diagram of an embodiment of a
directional diversity receive system.
[0020] FIG. 13 is flowchart illustrating a method of receiving a
signal at the embodiment of the directional receive system of FIG.
1.
[0021] FIG. 14 is an illustration showing different situations in
which the directional receive system of FIG. 1 may be utilized.
DETAILED DESCRIPTION
[0022] Depending on the application, one of several types of
antennas can be utilized to implement a wireless communication
system. For example, types of antennas that may be used are omni,
sector, and directional antennas. Those skilled in the art will
understand that an omni antenna may radiate energy, for example RF
energy, approximately in and receive energy approximately from all
directions, i.e. in a 360 degree azimuth. Those skilled in the art
will also understand that a sector antenna may radiate or receive a
cone of energy that is generally between approximately 50 and
approximately 120 degrees, and a directional antenna may radiate or
receive a beam of energy generally in one or more determined
directions with respect to the antenna. Directional antennas may
have an angle (beam-width) of signal reception or transmission that
is less than that of a sector antenna, which angle may be
determined by the specific configuration of the directional
antenna. For example, the beam-width of a parabolic antenna may be
determined by the size and shape of its parabolic reflector and the
frequency being transmitted or received. The beam of energy
transmitted or received by a parabolic antenna, and certain other
directional antennas, may in some instances be referred to as a
pencil beam because of its relatively narrow width as compared to
the energy radiated by other types of antennas. Antennas may be
"polarized" so that signals of differing polarizations can be
transmitted or received and discriminated against. Such polarized
antennas may assist in capturing only a desired signal.
[0023] Omni antennas generally have gains in the region of about 2
dBi to about 10 dBi (dBi refers to the relative gain/directivity of
an antenna with respect to an equivalent isotropic antenna, which
isotropic antenna radiates in all directions equally, expressed on
the decibel logarithmic scale). Sector antennas generally have
gains in the range of about 10 dBi to about 16 dBi. Directional
antennas generally have a gain greater than about 20 dBi with
beam-widths of less than about 10 degrees. In this description, the
term "high gain" will generally be used to describe a gain that is
higher than the 16 dBi that is typically achieved with generally
known sector antennas as described above. Sector and directional
antennas need to be pointed, either manually or automatically,
towards a target receive system or source transmit system, as their
beam-widths are less than 360 degrees. Directional antennas
specifically require the most care as their beam-widths are
typically less than about 10 degrees and in some cases less than
about 1 degree.
[0024] Those skilled in the art will understand that the above
antenna descriptions apply to both antennas used in transmit
systems, as well as antennas used in receive systems. Many antennas
can be used as either a transmit or receive antenna, or both in the
case of a bi-directional link. In addition, some receive systems
can be used as transmit systems, and similarly some transmit
systems can be used as receive systems. Although the use of the
antennas as disclosed above may be described below in reference to
embodiments specifically of a receive or transmit system, those
skilled in the art will recognize that many concepts and teachings
herein can also be used to implement either or both receive and
transmission systems.
Transmit Systems
[0025] A transmitter may accept audio, video, and/or other data as
its raw input and encode and modulate that data to a frequency
required for transmission. The raw data may be compressed and/or
encapsulated into an ASI (asynchronous serial interface) transport
stream. This stream may be fed to a modulator. The modulator may
spread the data out over multiple carriers, for example when the
modulator comprises a COFDM modulator. The modulated data is
up-converted to the required transmission frequency and may be
amplified to the desired power level before being presented to an
antenna for transmission. The antenna radiates the wireless energy
from the transmitter into the air.
Receive Systems
[0026] Traditional receive systems receive the modulated energy and
convert the energy back into its original form of audio, video,
and/or other data using an antenna to capture the RF energy and a
receiver to demodulate the signal. The radiated energy from the
transmit system is picked up via the antenna. If the receive system
comprises a sector or directional antenna, such antenna needs to be
pointed, either manually or automatically, towards the transmit
system. This need is due to the fact that the beam-widths of such
antennas are less than 360 degrees. The directional antenna
specifically requires the most care as the beam-widths are
typically less than about 10 degrees and in some cases less than
about 1 degree.
[0027] The receiver accepts the signal from the antenna. The
received signal may be amplified, and then down-converted to the
required demodulator input frequency range. The demodulator
converts the signal back to a compressed form and/or may convert
the signal back into an ASI stream. This converted signal is then
fed to the decoder of the receiver, which decoder converts the
signal back to the original source material at the decoder's output
(for example to audio, video, and/or other data).
[0028] Many receive systems, or sites, are located on "high points"
within a geographic area. These sites include tops of mountains,
hills, buildings, and radio towers. The sites may be unmanned and
remotely controlled from a central command and control site, adding
additional complexity to the system.
Planning Wireless Systems
[0029] When planning a wireless link there are many factors to take
into consideration. Important questions include: what are the link
and distance requirements? What frequency can be used? What type of
terrain will be encountered? Is the terrain urban, rural,
mountainous, water? Are there other signals that might interfere
with the transmitted signal or are there other signals that might
be interfered by the transmitted signal? How much data needs to be
transported across the link? Is the transmit platform stationary or
mobile? How robust does the system need to be? What is the budget
for the system?
[0030] The answers to these questions determine what equipment and
how complex a system is required to provide an acceptably
performing link. Long distances may require higher power
transmitters and/or greater gain from the antennas to overcome
atmospheric attenuation and fading. Certain wireless links are
inherently "line of sight" systems and a transmitted signal will
generally not pass through or bend around terrain or buildings.
Bouncing off such terrain or buildings creates natural multi-path
issues for the system. Thus, even shorter links can suffer from
natural multi-path issues. Unnatural multi-path may be an issue if
multiple users are allocated the same frequency or the operator
wishes to use the same channel simultaneously. Using directional
antennas and/or more sophisticated receiver technology may be
required to minimize this type of interference. The use of
directional antennas, however, may limit the azimuth of signal
reception, or continual adjustment of such antennas may be
necessary to ensure proper signal reception. Such adjustment may be
slow or necessitate laborious input by a trained operator. The use
of more sophisticated receiver technology may increase the cost of
the system and add complexity.
[0031] Data transfer rates within a transmit and receive system are
dependent on multiple parameters. For example, three such
parameters include modulation type, forward error correction (FEC),
and guard interval (GI). Low modulation types with high FEC and
long GI typically yield a robust link largely immune to both forms
of multi-path, but at the expense of data throughput. For large
data throughputs, which are necessary for high-definition (HD)
video, a higher modulation type with low FEC and increased GI is
needed which reduces the system's immunity to multi-path. In
general, an increase in the robustness of a link will necessitate
lowering the amount of data that can be transmitted. Similarly, an
increase in the amount of throughput will necessitate lowering the
error corrections that are included in the signal.
[0032] Selecting a receive antenna with a narrowed beam-width (and
thus an increased gain) will generally allow a signal to be
received from a greater distance and will increase the strength of
the received signal. A decrease in the beam-width, however, will
necessitate that the antenna be more carefully positioned to
correctly receive the signal. Similarly, selecting an antenna that
may receive signals over a wide azimuth may decrease the strength
at which signals may be received.
Directional Diversity Receive System
[0033] Embodiments of the receive system described herein relate to
increasing the likelihood of successfully receiving a transmitted
wireless signal. The system may be used with a radio frequency (RF)
link, for example that may be mobile or temporarily fixed. The RF
link may use the digital COFDM (Coded Orthogonal Frequency Division
Multiplexing) modulation/demodulation schemes to transmit either
encapsulated data or compressed video (Standard-Definition (SD) or
High-Definition (HD)). Such transmission may be executed with a
Super High Frequency (SHF). Those skilled in the art will
appreciate that embodiments described herein may also be utilized
to receive wireless signals over a link other than an RF link, or
may be used to receive signals that do not utilize the COFDM scheme
or are not transmitted with an SHF.
[0034] Receive system performance can be enhanced with the addition
of diversity. Traditional diversity can be either frequency or
spatial. Frequency diversity requires two transmitters on unique
frequencies and two receivers; one receiver is set to one of the
frequencies and the second receiver is set to the remaining
frequency, wherein both signals are received by the same antennas.
Spatial diversity uses two receive antennas, sometimes spaced apart
by a minimum number of a desired frequency's wavelength, and two
receivers, wherein a separate receiver is connected to each
antenna. In general, one of a multi-path and signal fading
characteristic is good when the other is bad. In some situations,
performance is improved as much by using unique frequencies as by
using multiple receive antennas. Switching between receiver
outputs, manually or automatically, may allow a system to obtain
the correct audio, video, and/or data. Frequency and spatial
diversity can be combined to add additional robustness.
[0035] A system designed for higher data throughput may reduce
multi-path interference with antenna choices and the use of
diversity. If a platform is mobile, either receive or transmit, the
complexity of the system goes up dramatically, requiring computer
controlled antennas and auxiliary data links to provide positional
information for the control system to "track" the platform. If the
mobile platform is a person, the size and weight of the transmit
system becomes paramount, requiring a more sophisticated receive
system.
[0036] One way to enhance traditional spatial diversity of a
receive system includes using a third diversity option, which may
be referred to as Maximal Ratio Combining (MRC). MRC enhances
traditional spatial diversity (i.e. two antennas and two receivers)
by considering receiver output quality at a packet level, for
example at an ASI transport stream packet level. Each demodulator
of the receive system presents, good or bad, packets to the MRC
combiner, which in turn generates a good one from any of the
demodulators outputting a good packet and then adds the good packet
to a combined ASI transport stream. The system then repeats this
process of generating a good packet for each subsequent packet. In
this way, the decoder may receive a more robust transport stream
than would be possible with only one antenna and one receiver. The
combining is much more efficient, and can be executed much faster
and using more automation than traditional spatial diversity. In
some embodiments, MRC systems utilize two (2), three (3), four (4),
five (5), six (6) or more antenna and receiver/demodulator
combinations.
[0037] As with all engineering systems, the selection of the
components involves compromises. Budget constraints are generally
paramount. Equipment costs can increase dramatically when diversity
is required, and larger antennas may not be practical on certain
towers and may also be cost prohibitive. Adding antennas at
different locations adds recurring costs for the space that those
antennas occupy.
[0038] Embodiments disclosed herein may include a fully integrated
directional diversity receive system for audio, video, and/or data.
Disclosed embodiments may allow for receiving a signal with an
increased gain, while concurrently receiving the signal over a
wider azimuth as compared to receive systems known in the art.
Disclosed embodiments additionally may allow a high data throughput
while maintaining the robustness of a received signal. To add to
this, disclosed embodiments may provide a cost effective system
that utilizes diversity to receive wireless signals, for example RF
signals.
[0039] In some embodiments, a directional diversity receive system
comprises at least one steerable high-gain directional antenna and
at least one diversity panel antenna. The signals from these
antennas may be fed into one or more Maximum Ratio Combining (MRC)
Diversity Receiver(s).
[0040] As can be seen in a front view of an embodiment of a
directional diversity receive system 100, illustrated in FIG. 1,
the system 100 may include a plurality of antennas 102 attached to
and fixed with respect to a frame 104. The system 100 additionally
includes a directional antenna 108 attached to the frame 104. In
some embodiments, the directional antenna 108 is moveable with
respect to the frame 104 and/or may be steerable such that it may
be pointed toward a given signal source or direction.
[0041] In the illustrated embodiment, the system 100 comprises five
antennas 102a-102e fixed with respect to the frame. The system 100
is not limited to five fixed antennas, however, and may comprise a
greater or lesser number of such fixed antennas 102. In some
embodiments, the system 100 comprises one, two, three, four, five,
six, seven, eight, nine, ten, or more fixed antennas 102.
[0042] In FIG. 1, the frame 104 is illustrated as comprising an
upper rim 105 and a plurality of posts 106 extending from the rim
105. In the illustrated embodiment, the system 100 comprises five
posts 106a-106e, each of which is positioned between two of the
antennas 102. The rim 105 is illustrated as supporting the posts
106 and may at least partially define the orientation of the posts
106. For example, the posts 106 may be arranged in a circumference
about a central area. Each of the antennas 102 is illustrated as
being attached to two posts 106, one on each side of the antenna
102. In some embodiments, one or more of the antennas 102 are
attached to only one post 106. In some embodiments, one or more of
the antennas 102 are additionally or instead attached to the rim
105. In these embodiments, one or more of the posts 106 may be
omitted. In some embodiments, the rim 105 is omitted. For example,
the frame 104 may comprise a plurality of brackets that
mechanically connect a plurality of antennas without the use of a
rim. In other embodiments, a rim is disposed underneath a plurality
of antennas and/or a plurality of posts.
[0043] The frame 104 may be configured as any number of mechanical
means that attach a plurality of antennas together. In some
embodiments, the system 100 is configured to be relocated as an
integral unit such that the fixed antennas 102 and directional
antenna 108 may be moved simultaneously. The frame 104 may be made
of any material that can secure a plurality of antennas. For
example, the frame may comprise an aluminum or other metal
material. The frame 104 is not limited to embodiment illustrated in
FIG. 1, but may be configured in any number of ways, for example as
illustrated and described with respect to FIG. 8.
[0044] The plurality of fixed antennas 102 are arranged to provide
spatial diversity when receiving a wireless signal. The spatial
diversity allows for more accurate and robust reception of the
wireless signal, as described above. In some embodiments, the
system 100 utilizes COFDM MRC receiver technology. In such
embodiments, each fixed antenna 102 is connected to a receiver, and
packets are selected for inclusion in a transport stream. In some
embodiments, the packets are ASI packets that are selected for
inclusion in an ASI transport stream.
[0045] In the illustrated embodiment, the plurality of fixed
antennas 102 comprise a plurality of sector antennas. The plurality
of sector antennas allow the system 100 to receive signals over a
wide azimuth, while providing an increased gain at each antenna
compared to the use of an omni antenna. The sector antennas may
comprise panel antennas or any other type of sector antenna. In
some embodiments, the antennas 102 comprise one or more
reconfigurable diversity panel antennas. In the illustrated
embodiment, the sector antennas comprise "can" antennas. Such "can"
antennas may comprise a slotted dipole type antenna, for example
configured as a cavity backed dipole array. Each sector antenna of
the system 100 may comprise the same type of sector antenna, or a
combination of different types of sector antennas can be used.
[0046] Each of the fixed antennas 102 may be configured similar to
every other fixed antenna, or the system 100 may comprise a
plurality of differently configured fixed antennas 102. In some
embodiments, the fixed antennas 102 each have a gain of
approximately 12 dBi. In other embodiments, the fixed antennas each
have a gain of approximately 8 dBi. In still other embodiments,
antennas of a plurality of different gains are implemented. One or
more of the antennas may have an azimuth of reception of
approximately 75 degrees, and may have an elevation of reception of
approximately 38 degrees. One or more of the antennas may be
polarized, for example to exhibit vertical polarization, and one or
more antennas may be configured with a quad pole. For example, two
cavities each having a dipole antenna and attached to a single
panel, as illustrated in FIG. 1, may be configured as a quad pole.
Alternatively, an antenna having a single antenna may be configured
with a quad pole.
[0047] FIG. 2 shows a perspective view of the system 100. As can be
seen, the system 100 is illustrated as having a cover 110 partially
enclosing the system 100. The embodiment shown is configured with
the cover 110 surrounding the antennas 102a-102e. In this
configuration, the cover 110 may protect the antennas 102a-102e
while still allowing the directional antenna 108 to freely operate.
The cover 110 may additionally comprise a lower surface (not shown)
that wholly or partially encloses the portion of the system 100
facing in a downward direction in FIG. 2.
[0048] In the illustrated embodiment, the cover 110 is attached to
the rim 105. In other embodiments, the cover 110 may be attached to
one or more of the posts 106 or any other portion of the system 100
to secure the cover 110. Although the cover 110 is illustrated as
being substantially circular, the cover 110 may be configured in
any number of shapes or sizes. The cover 110 may be made from a
variety of materials that allow wireless signals to be received by
the antennas 102a-102e from an area outside of the cover 110, for
example from a plastic or alloy material.
[0049] The directional antenna 108 may be movable with respect to
the frame 104 and/or the cover 110. In this way, the directional
antenna 108 may be steered so as to rotate to face a plurality of
directions. In some embodiments, the directional antenna 108 is
configured to rotate 360 degrees. Thus, the directional antenna 108
can face, and receive signals from, any direction. In this way, the
frame 104 and/or the cover 110 can be anchored to a structure while
still allowing the directional antenna 108 to freely rotate. In
other embodiments, the directional antenna is fixed with respect to
the frame 104, and the frame 104 and the directional antenna 108
may be configured to rotate in unison. In such embodiment, the
frame 104 may be configured to rotate within the cover 110. Some
embodiments of the system 100 comprise a servo or other motor or
mechanism for causing the directional antenna 108 to rotate.
[0050] A gain of the directional antenna 108 may be greater than a
gain of any of the fixed antennas 102. In the illustrated
embodiment, the directional antenna 108 is depicted as a parabolic
antenna, and the directional antenna 108 has a gain greater than
any of the sector antennas 102a-102e. For example, the gain of the
directional antenna 108 may be about 20 dBi when receiving a signal
in a frequency band of approximately 1.9-2.5 GHz, about 22 dBi when
receiving a signal in a frequency band of approximately 4.9 GHz, or
about 26 dBi when receiving a signal in a frequency band of
approximately 6.5-7.2 GHz. Alternatively, the gain of the
directional antenna may be approximately the same when receiving
over several frequency bands. For example, the gain of the
directional antenna may be about 16 dBi when receiving a wireless
signal in any of the above-described frequency bands. In
comparison, the sector antennas 102a-102e described above may have
gains ranging from approximately 8 dBi-12 dBi. In some embodiments,
the gain of the directional antenna 108 is approximately twice the
gain of any of the fixed antennas 102. The directional antenna 108
may be polarized, for example to exhibit vertical polarization, or
may be configured with a quad pole.
[0051] Those of skill in the art will understand that the above
descriptions of the antennas 102 and 108 are not exhaustive of the
different types, configurations, or combinations of antennas that
may be implemented in the system 100. For example, the directional
antenna 108 may comprise a parabolic antenna having a different
configuration, as shown in FIG. 3, or may comprise a different type
of directional antenna, such as a yagi antenna as illustrated in
FIG. 8. Those of skill in the art will recognize additional types,
configurations, and combinations of antennas that may be
implemented in the system 100 in accordance with the principles
described above.
[0052] As can be seen in an overhead view of the system 100,
illustrated in FIG. 4, the fixed antennas 102 and/or the frame 104
may be arranged to define a circumference. In the illustrated
embodiment, the frame 104 and fixed antennas 102 form a perimeter
around the directional antenna 108, and are arranged to receive a
wireless signal from any direction within a 360 degree azimuth.
Thus, the fixed antennas 102 may receive a wireless signal
regardless of the direction from which it was transmitted or
redirected by environmental factors. In some embodiments, each of
the illustrated fixed antennas 102a-102e receives a wireless signal
over an azimuth of approximately 70-80 degrees.
[0053] In the illustrated embodiment, the fixed antennas 102 are
equally spaced and angled about the circumference. Thus, the fixed
antennas 102 form the shape of a pentagon. Such configuration will
increase the likelihood of receiving a wireless signal regardless
of the direction from which it is being propagated. The fixed
antennas 102 are configured to receive signals at least from a
direction opposite the inside of the pentagon. In other
embodiments, the fixed antennas 102 are not equally spaced or are
not equally angled about the circumference.
[0054] In some embodiments, the fixed antennas 102 do not form a
circumference. For example, the fixed antennas 102 may be arranged
to primarily face in one or several directions. Such arrangement
may be beneficial, for example, when signals are likely only to be
received from certain directions and when it is possible to
implement such arrangement using fewer fixed antennas to reduce
costs. The azimuth over which a fixed antenna may receive signals
may be selected based on the requirements of the system 100.
[0055] In some embodiments, one or more of the fixed antennas 102
comprise an aluminum panel. The aluminum panel comprises a large
ground plane to improve the performance of the fixed antennas 102.
In other embodiments, one ore more surfaces of the fixed antennas
102 are coated with a metal material. Such surface coating may
reduce the amount of radiation that is absorbed through the back of
an antenna. Thus, the antenna can be configured to receive signals
from only directions that the antenna faces.
[0056] In some embodiments, one or more of the fixed antennas 102
are configured to detach from the frame 104. When detached, the one
or more antennas can be remotely mounted away from the frame 104
and will still receive wireless signals. These signals can be used
by the system 100 to provide audio, data, and/or video as described
above. Such detachment may be useful in providing greater spatial
diversity than when all of the fixed antennas 102 are attached to
the frame 104, and allows for an antenna arrangement that is
customizable by a user of the system 100.
[0057] The directional antenna 108 may be configured to implement
MRC technology in association with the fixed antennas 102. Thus,
the system 100 would be able to receive a signal using any of the
attached antennas and generate a packet of data from the received
signal. In this way, an unexpected shift in the direction from
which a signal is being received will not substantially affect
proper reception of the signal. Even if the quality of a signal as
received at one of the antennas degrades, it is likely that another
one of the antennas will receive the signal with sufficient
quality. The directional antenna 108 may be configured to receive
wireless signals modulated according to a COFDM scheme.
[0058] In the illustrated embodiment, the single directional
antenna 108 is located within a circumference of the fixed antennas
102. In other embodiments, the directional antenna 108 may be
located outside of the circumference, or the fixed antennas 102 may
not form a circumference. In still other embodiments, more than one
directional antenna 108 may be provided.
[0059] While the fixed antennas 102 may receive signals from a
larger number of directions at a given time, the directional
antenna 108 may receive the signals with a higher gain. Thus,
benefits of spatial diversity can be combined with benefits of
increased signal strength. The number of antennas and configuration
of each antenna can be selected based on desired use or location of
the system 100, or according to cost requirements. Thus, a
cost-effective system for reliably receiving a signal from any
direction may be implemented.
[0060] As can be seen in a side and front view of the system 100,
illustrated in FIG. 5 and FIG. 6, respectively, the cover 110 may
completely encase a lower portion of the system 500. In the
illustrated embodiment, the cover 110 surrounds the circumference
defined by the frame 104 and the antennas 102. The cover 110
comprises a plurality of feet 112a-112e that may be configured to
mount or anchor to a surface or structure. In other embodiments,
one or more of the feet 112a-112e are omitted. The feet 112 may be
configured as any supports on which the system 100 can rest or be
anchored. In some embodiments, the cover 110 has a plurality of
holes formed in a lower surface thereof to allow supports formed on
the frame 104 to pass through the cover 110 and contact a mounting
surface or structure.
[0061] The embodiment illustrated in FIGS. 5 and 6 shows an output
150 accessible from a lower surface of the cover 110. In other
embodiments, the output 150 is accessible from a side of the cover
110, or is only accessible from inside the cover 110. The output
150 may output data received at one or more of the antennas 102.
The output data may first be down-converted to a lower frequency,
amplified, and/or demodulated, for example by a receiver or
demodulator. In some embodiments, the system 100 comprises a
plurality of outputs, for example an output that corresponds to
each of the antennas 102a-102e. In some embodiments, the system 100
is configured with a single output for outputting data received at
all of the antennas 102 and 108. In this configuration, the output
may transmit packets to another device, for example a controller or
combiner configured to implement an MRC selection of the data
and/or packets received from the output. In some embodiments, the
output 150 is configured to accept a single multi-core control
cable, and is further configured to transmit data over the control
cable to a controller.
[0062] FIG. 7 shows another side view of the system 100, where the
side view is taken from the side furthest from the viewer in FIG.
5. As can be seen, the system 100 is illustrated as having a cover
170 partially enclosing the system 100. The embodiment shown is
configured with the cover 170 surrounding the directional antenna
108. The cover may wholly or partially enclose the portion of the
system 100 above the rim 105. In the illustrated embodiment, the
cover 110 and the cover 170 cooperate to complete enclose the
antennas 102, the frame 104, and the directional antenna 108. In
this way, the system 100 may be completely encased.
[0063] The cover 170 may be attached to the rim 105, one or more of
the posts 106, the cover 110, or any other portion of the system
100. Although the cover 170 is illustrated as being substantially
circular, the cover 170 may be configured in any number of shapes
or sizes. The cover 170 may be made from a variety of materials
that allow wireless signals to be received by the directional
antenna 108 from an area outside of the cover 170, for example from
a plastic or alloy material. The covers 110 and 170 may have a
solid construction, as shown in FIG. 7, or one or both of the
covers 110 and 170 may have one or more holes formed therein.
[0064] Those skilled in the art will appreciate that the system 100
may be configured for relocation as an integrated module. Thus, the
plurality of fixed antennas 102, the frame 104, and the directional
antenna 108 may be integrated into a single unit that combines a
plurality of panel antennas with a directional antenna of higher
gain. For example, the antennas and frame may all be mechanically
connected, as described above, or enclosed within one or more
covers, also as described above. In this way, spatial diversity can
be achieved by the panel antennas and increased signal reception
strength can be achieved by the directional antenna. In addition,
the integrated unit reduces the cost to the user by allowing the
user to implement the spatial diversity and increased signal
reception strength in a limited spatial area. In some embodiments,
the enclosed system 100 including the covers 110 and 170 is less
than approximately 35 inches high by 45 inches wide by 45 inches in
depth. In one embodiment, the enclosed system 100 including the
covers 110 and 170 is approximately 29.125 inches high by 40 inches
in diameter when measured without the feet 112. In one embodiment,
the feet 112 are approximately one inch tall.
[0065] FIG. 8 shows a perspective view of an embodiment of a
directional diversity receive system 200. The system 200 may
include a plurality of antennas 202 attached to and fixed with
respect to a frame 204. The system 200 additionally includes a
directional antenna 208 attached to the frame 204. The system 200
may further include a cover 210 configured to partially or wholly
encase the system 200.
[0066] The frame 204 is illustrated in FIG. 8 as comprising a
plurality of support arms 205 extending down from a rigid ring 206
centrally disposed within the system 200. In the illustrated
embodiment, the system 200 comprises five support arms 205a-205e
(arm 205c is not illustrated in FIG. 8), each of which downward
from the rigid ring 206 towards an area between two of the antennas
202. The ring 206 may at least partially define the orientation of
the arms 205, and the ring 206 and/or one or more of the support
arms 205 may support the cover 210 so that the cover 210 does not
interfere with the operation of the directional antenna 208. The
arms 205 may be arranged in a circumference about a central area,
similar to how the posts 106 described with respect to the system
100 are arranged. Although the ring 206 is illustrated as being
centrally disposed within the system 200 and the arms 205 are
illustrated as extending from this central location, as can be most
easily seen in an overhead view of the system 200 illustrated in
FIG. 9, the ring 206 may be located at a different location and in
some embodiments is not formed as a ring.
[0067] Each of the antennas is shown as being attached to a lower
surface 207 of the system 200. In addition, each of the antennas
202 is illustrated as being supported in an upright configuration
by two support arms 205, one on each side of the antenna 202. In
some embodiments, one or more of the antennas 202 are attached to
only one arm 205. In some embodiments, one or more of the antennas
202 are not attached to any support arms, but are fully supported
by their attachment to the lower surface 207. In some embodiments,
one or more of the antennas 202 are not supported by the lower
surface 207 but instead are supported by one or more support arms
or by other antennas.
[0068] As described above with respect to the system 100, the frame
204 may be configured as any number of mechanical means that attach
a plurality of antennas together. In some embodiments, the system
200 is configured to be relocated as an integral unit such that the
fixed antennas 202 and directional antenna 208 may be moved
simultaneously. The frame 204 may be made of any material that can
secure a plurality of antennas, and may otherwise be configured
similar to the frame 104 described with respect to the system
100.
[0069] The plurality of fixed antennas 202 are arranged to provide
spatial diversity when receiving a wireless signal. In the
illustrated embodiment, each of the plurality of fixed antennas 202
comprise a sector antenna. The sector antennas are as dipole
antennas each having a single cavity, in contrast the antennas 102
illustrated in FIG. 1. Each sector antenna 202 of the system 200
may comprise the same type of sector antenna, or a combination of
different types of sector antennas can be used.
[0070] Each of the fixed antennas 202, however, may be configured
similar to every other fixed antenna, or the receive site system
200 may comprise a plurality of differently configured fixed
antennas 202. The antennas 202 may otherwise be configured similar
to the plurality of antennas 102 described above with respect to
the system 100.
[0071] The cover 210 is illustrated as being cut away so as to show
the components of the system 200 in detail. The cover 210, however,
may span over the entirety of the frame 204. In this way, the cover
210 may cooperate with the lower surface 207 to wholly enclose the
system 200. In other embodiments, the cover 210 only partially
encloses the system 200. The cover 210 may attach to the lower
surface 207, the frame 204, and/or any other portion of the system
200. Although the cover 210 is illustrated as being substantially
circular, the cover 210 may be configured in any number of shapes
or sizes. The cover 210 may be made from a variety of materials
that allow wireless signals to be received by the antennas
202a-202e and 208 from an area outside of the cover 210, for
example from a plastic or alloy material. The cover 210 may
otherwise be configured similar to the cover 110 described above
with respect to the system 100.
[0072] A gain of the directional antenna 208 may be greater than a
gain of any of the fixed antennas 202. In the illustrated
embodiment, the directional antenna 208 is depicted as a
two-element yagi antenna, as can be seen in detail in a front view
and a side view of the system 200, illustrated in FIG. 10 and FIG.
11, respectively. The directional yagi antenna 208 has a gain
greater than any of the sector antennas 202a-202e, and may be
movable with respect to the frame 204 and/or the cover 210. The
directional antenna 208 may otherwise be configured similar to the
directional antenna 108 described above with respect to the system
100.
[0073] Those skilled in the art will appreciate that the system 200
may be configured for relocation as an integrated module. Thus, the
plurality of fixed antennas 202, the frame 204, and the directional
antenna 208 may be integrated into a single unit that combines a
plurality of panel antennas with a directional antenna of higher
gain. In some embodiments, the system 200 is smaller in one or more
physical dimension than the system 100. This difference in size may
be due to the use of individual components which are smaller in
nature, for example a yagi antenna as compared to a parabolic
antenna, or a panel antenna having a single cavity as compared to a
panel antenna having two cavities. The difference in size may also
be due to the design of the frame 204 as compared to the design of
the frame 104, or due to some other factor not herein discussed. In
some embodiments, the enclosed system 200 including the cover 210
is less than approximately 15 inches high by 30 inches wide by 30
inches in depth. In one embodiment, the enclosed system 200
including the cover 210 is approximately 13.5 inches high by
approximately 25 inches in diameter when measured without the feet.
In one embodiment, the enclosed system 200 including the cover 210
is approximately 13.5 inches high by approximately 27 inches in
diameter when measured with the feet. The system 200 may otherwise
be configured similar to the system 100. For example, the system
200 may comprise a single output.
[0074] FIG. 12 is a functional block diagram of an embodiment of a
directional diversity receive system 1200, for example as may be
used to implement the system 100 or 200 described above. The system
1200 comprises a plurality of antennas 1202. The plurality of
antennas may comprise one or more directional antennas, for example
as illustrated by an antenna 1202f, in combination with one or more
fixed antennas, for example as illustrated by antennas 1202a-1202e.
The directional antenna 1202f may be moveable and the fixed
antennas 1202a-1202e may be fixed with respect to the directional
antenna. The fixed antennas 1202a-1202e may comprise sector
antennas. In the illustrated embodiment, six antennas 1202a-1202f
are shown. The antenna 1202f may represent the antenna 108 or 208
of FIGS. 1 and 8, respectively, and the antennas 1202a-1202e may
represent the antennas 102 or 202 of FIGS. 1 and 8, respectively.
In some embodiments, a greater or lesser number of antennas are
used. The types and combinations of antennas may vary from those
described above.
[0075] The system 1200 may further comprise a plurality of
receivers/demodulators 1204a-1204f and a combiner/controller 1206.
Each of the receivers/demodulators 1204a-1204f are connected to a
respective one of the antennas 1202a-1202f. The
receivers/demodulators 1204a-1204f are configured to convert
wireless signals received by the antennas 1202a-1202f into
appropriate electrical signals and to demodulate and decode the
appropriate electrical signals. For example, the
receivers/demodulators 1204a-1204f may be configured to convert an
RF signal into a baseband or intermediate signal, and may be
further configured to decode data into a bit stream. The
receivers/demodulators 1204a-1204f are further configured to
present data, for example in the form of packets containing the
data, to the combiner/controller 1206. In some embodiments, the
packets comprise ASI packets.
[0076] The illustrated embodiment shows that the antennas
1202a-1202f and the receivers/demodulators 1204a-1204f may be
combined within a single unit 1210. For example, the unit 1210 may
comprise the cover 110 and/or the cover 170 illustrated in FIG. 7,
or the unit 1210 may comprise the cover 210 illustrated in FIG. 8.
Thus, the systems 100 and 200 may comprise receivers/demodulators
in addition to the components already described above. Each
receiver/demodulator may be attached to the frame 104 or 204, and
each may be connected to a respective antenna 102a-102e and 108, or
202a-202e and 208. It will be appreciated, however, that all the
functionality of FIG. 12 need not be wholly enclosed, and that the
functionality of FIG. 12 may be implemented in the same or separate
devices, circuits, or software modules. For example, the
receivers/demodulators 1204a-1204f may be implemented on a single
chip, but may process data received from the antennas 1202a-1202f
individually.
[0077] The data presented to the combiner/controller 1206 by the
receivers/demodulators 1204a-1204f may be presented in a single
output or stream, as illustrated in FIG. 12. Thus, the data output
by the receivers/demodulators 1204a-1204f may be communicated using
the single output 150 of the system 100. In other embodiments, each
of the receivers/demodulators 1204a-1204f present data individually
to the combiner/controller 1206. In still other embodiments, one or
more of the receivers/demodulators 1204a-1204f present data
individually to the combiner/controller 1206, while others of the
receivers/demodulators 1204a-1204f present data in a combined
stream.
[0078] The combiner/controller 1206 is configured to receive data,
for example in the form of packets which may comprise ASI packets,
from each of the receivers/demodulators 1204a-1204f, and to
generate a good packet from the packets output by the
receivers/demodulators 1204a-1204f. This good packet is output for
reproduction, for example to a HD or SD video decoder. Each
successive good packet is output by the combiner/controller 1206 to
produce a combined packet stream suitable for reproduction. In this
way, the receive system 1200 may be configured to implement MRC by
receiving wireless signals with the plurality of antennas 1202. In
this way, multipath propagation and/or shifts in the direction from
which a signal is being received will not substantially affect
proper reception of the signal. In the illustrated embodiment, the
combiner and controller is illustrated as being a single device,
but in some embodiments the combiner and controller may be
implemented in separate devices, circuits, or software modules, or
there may be a plurality of combiners and/or controllers.
[0079] In some embodiments, the receive system 1200 further
comprises means for down-converting or up-converting the signal
frequency to fit the frequency expected by a receiver, which may be
implemented instead of or in addition to the receivers/demodulators
1204a-1204f. Also, in some embodiments, the receive system 1200
further comprises means for filtering of a signal, for example
filtering of an RF signal. Additionally, in some embodiments, the
receive system 1200 further comprises a means for individual
antenna polarization.
[0080] In some embodiments, the receivers/demodulators 1204a-1204f
and/or the combiner/controller 1206 is configured to calculate
metrics describing the amount and quality of wireless signal (which
may be called "receiver metrics") being received by the antennas
1202a-1202f. These metrics can be use, for example by the
combiner/controller 1206, to determine which antenna received the
signal with the greatest strength or quality. Such information may
be presented to a user of the receive system 1200, for example
using a display device (not illustrated), or may be used by the
combiner/controller 1206 to command a directional antenna of the
system 1200 to rotate. Such movement may increase or maximize the
signal energy being received by the directional antenna. The system
1200 can then maintain this relationship in which the directional
antennas receives a maximized signal energy by constantly
evaluating the receiver metrics and adjusting the position of the
directional antenna.
[0081] FIG. 13 is flowchart illustrating a method 1300 of receiving
a signal at a directional receive system, for example at the system
100 illustrated in FIG. 1. The acts associated with the method 1300
may be performed by different configurations of the system 100 than
those herein described. Those skilled in the art will know how to
extend the method described to different configurations of the
receive site system 100.
[0082] At block 1302, a wireless signal is received using a
plurality of fixed antennas. As described above, the fixed antennas
may be arranged to provide spatial diversity.
[0083] At block 1304, it is determined which of the fixed antennas
received the wireless signal with the highest robustness. The
robustness may be determined using a variety of parameters. For
example, at least one of a signal to noise ratio, a modulation
error ratio, a signal strength, and a pre-Viterbi or post-Viterbi
bit error rate may be used in the determination. The pre-Viterbi
and/or post-Viterbi bit error rate may indicate the proportion of
error correction that is performed on a signal, and may reveal the
portions of the signal that are recovered. The determination may be
performed by any sort of computer, controller, microcontroller, or
other logic device. The determination process can be automated such
that a user or operator of the receive site system need input
little or no information.
[0084] At block 1306, a directional antenna is rotated so as to
approximately align with the direction of the fixed antenna that
received the wireless signal with the highest robustness. In this
way, the chances of properly receiving the wireless signal at the
receive site system can be greatly increased. Not only can the
fixed antennas be used to receive the wireless signal, they can be
used to steer the directional antenna. As described above, the
directional antenna may comprise a high-gain directional
antenna.
[0085] At block 1308, the directional antenna--in this embodiment,
a high-gain directional antenna--may seek the wireless signal
within the beam-width of the fixed antenna that received the
wireless signal with the highest robustness. The high-gain
directional antenna may have a narrower beam width than the
determined fixed antenna. Thus, the high-gain directional antenna
may not be able to receive signals over an azimuth similar to the
determined fixed antenna.
[0086] To promote accurate signal reception, the high-gain
directional antenna may seek the wireless signal or perform
dithering to point in the direction which receives the wireless
signal with the most robustness. The robustness of the signal
received at the high-gain directional antenna may be determined as
explained above in reference to block 1304. In addition to or in
alternative to performing the robustness determination described
above on the wireless signal received at the high-gain directional
antenna, the robustness of the wireless signal received at fixed
antennas surrounding the determined fixed antenna may be determined
to estimate the direction in which the high-gain directional
antenna should rotate. The high-gain directional antenna may
continually seek the wireless signal.
[0087] The method 1300 may be automated such that little or no
input is required by a user or operator of the receive site system.
For example, the controller 1206 illustrated in FIG. 12, or other
computer or automation device, may be used to automate the method
1300. The process 1300 may thus increase the speed and accuracy at
which a signal may be tracked. To add to this, the reception of a
signal with the fixed antennas while the directional antenna is
being moved may reduce the need for dithering. A wireless signal
may be properly received even if the steerable antenna is out of
position or is in the process of moving. Of course, a user may also
manually steer or rotate the directional antenna.
[0088] FIG. 14 is an illustration showing different situations in
which the directional receive system of FIG. 1 may be utilized. In
the illustrated embodiment, a directional diversity receive system
is shown as being implemented on top of a communications tower.
This receive system may comprise the system 100 or the system 200.
The receive system may also be mounted on a building or other
structure, or may be mounted on a moving receiver. The receive
system may receive data from any number of sources, including
automobiles such as police, fire and public safety vehicles;
military and reconnaissance vehicles; and broadcast or
telecommunications vehicles. The receive system may also receive
data from aircraft such as helicopters, unmanned aerial vehicles
(UAVs), aerostats or blimps, and fixed wing airplanes. The receive
system may also receive control signals via a wired or wireless
link, for example from a command center that is either automated or
controlled by a user. Those of skill in the art will recognize
other sources that may transmit data to the receive system.
[0089] In addition, a directional diversity receive system may be
mounted on one or more mobile vehicles. For example, the receive
system may be mounted on a news van and configured to receive
signals from a tower or news station. In such embodiment, the
system 200 may be advantageously utilized because of its relatively
reduced size. The use of a directional diversity receive system as
described herein may allow proper reception of signals even when
the signal source is moving, such as when the signal is being
transmitted from a mobile vehicle, or even when the receive system
is moving, such as when the receive system is mounted on a mobile
vehicle.
[0090] Those of skill in the art will appreciate that receive
systems described herein may advantageously be used in environments
where multi-path interference is high. Fixed antennas may receive
signals from all directions, and the use of data selection methods
such as MRC may allow data received at any antenna to be utilized.
A directional antenna may be steered to pick up signals from a
greater distance. Even when the directional antenna experiences
interference due to multi-path, however, it is likely that one or
more of the fixed antennas will receive and be able to demodulate a
desired signal. Such environment is often experienced in urban
settings where a transmitted signal reflects off of many buildings
and other structures.
[0091] Embodiments disclosed herein may allow the addition of more
receivers, demodulators, and/or antennas into a receive system.
Thus, the receive system may avoid signal propagation and reception
issues by using diversity, while reducing overall cost of the
system and increasing ease of use. The receive system may be
operated to automatically track a signal to ensure that the signal
is received with the highest possible robustness. In this way, the
input and sophistication required of a user is reduced.
[0092] The structure and the operation of the disclosed system and
methods are not limited to the above descriptions. Various
modifications may be made without departing from the spirit and
scope of the present invention. While the above description has
shown, described, and pointed out novel features of the system and
methods as applied to various embodiments, it will be understood
that various omissions, substitutions, and changes in the form and
details illustrated may be made by those skilled in the art without
departing from the spirit of the invention.
* * * * *