Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SY-~.TEM FOR DECRYPTING TELEVISION FROM SEVERAL SATELLITES
This invention relates to a syStem and corresponding
method for receiving a plurality of differently encrypted
signals, selecting one of the signals, and decrypting the
selected signal for subse~uent viewing. More
particularly, this invention relates to a system
including a decrypting device capable of simultaneously
housing a plurality of removable decrypting smart cards,
each card storing a different decrypting algorithm, so
that a user or viewer can scan received signals from
different satellites, select one for viewing, and have
~he selected signal decrypted using the appropriate card
and thereafter shown.
B~CKGRQUND OF THE INVENTION
The use of geosynchronous satellites to distribute
television signals is known in the broadcasting industry
and has helped revolutionize television distribution
systems. As is known, there are many communications
satellites encircling the earth occupying so-called
"geosynchronous orbits" me~n~ng that the satellites
appear to be stationary relative to fixed points on
earth. These satellites receive television signals
originating from earth ("uplink" signals) and retransmit
the signals back to earth (retransmitted signals are
called "downlinkl' signals). While such satellites
-- typically employ directional antennas to transmit
,
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downlink signals, the high altitude of the satellites
enables a large portion of the earth to receive the
downlink signals. Thus, a single satellite can
distribute television signals to entire continents or
large portions of continents, and receiving antennas on
such continents are capable o~ receiviny signals from a
plurality of such satellites.
Home television users or viewers obtain such
satellite signals via either a satellite receiving
antenna/system located at the user's residence or
alternatively by way of a cable distribution network
including a cable headend. In rural and remote areas
where cable is unavailable or even undesirable, viewers
often utilize their own satellite receiving
15 station/converting station for receiving satellite
television transmissions ~rom the above-identified direct
broadcast satellites (DBS). Such stations typically
include a satellite receiving parabolic antenna or dish
and associated motor-controlled positioning mount, as
20 well as a low noise amplifier (LNA) located at the
antenna for amplifying weak signals, a LNA block
converter stage for down-converting the block of
transponders or channels received, a conventional
satellite receiver which perform~ channel selection and
25 frequency/mode conversion, and a standard
television/video monitor.
Typically, a satellite broadcast signal in a
frequency range of about 12 GHz is received by a DBS
antenna such as a parabolic antenna erected outside of
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the viewer's home. The satellite broadcast signal is
converted into a BS-~F signal in a ~requency range from
about 950 to 1,450 MHz and is subsequently supplied to a
tuner. At the tuner, the desired satellite broadcast
5 c~nnel i8 selected from the BS-IF signal and demodulated
into video and audio which are then supplied to the
television set.
For example, U.S. Patent Mo. 4,796,032 discloses a
satellite broadcasting receiving system including a
parabolic antenna, antenna control system for directing
the antenna, signal processing section, and video/audio
display system. A parabolic antenna receives the
television waves from the satellite towards which it is
directed and forwards to the received signal to a signal
15 processing section which transforms the signal into one
which can be used by the video/audio display.
Unfortunately, the user/viewer of the signal received by
the system o~ the '032 patent is limited to viewing
signals sent by the particular satellite at which the
20 parabolic antenna is directed. If the user/viewer wishes
to view signals from another satellite, the user must
actuate the antenna control section motor which
repositions the parabolic antenna to receive such
signals. This is a time consuming and burdensome routine
25 which must be gone through each time the viewer wishes to
change satellites.
U.S. Patent No. 4,993,006 discloses a system for
receiving a scrambled satellite television signal and
unscrambling same for subsequent output. The
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unscrambling circuit in the system includes a user
exchangeable plastic card which contains an electronic
circult which provides the key for a corresponding
unscrambling circuit. By removing one card and replacing
5 it with another, the decoding characteristics of the
reception circuit can be changed. Unfortunately, the
reception circuitry of the '066 patent can only receive
one descrambling card at a time, and the user/viewer is
limited to viewing scrambled signals which can be
o descrambled by that card.
U.S. Patent No. 5,426,701 discloses a cable
television converter box with a smart card connector
attached thereto, the smart card storing a predetermined
signal security decrypting algorithm. Unfortunately,
this system, as those discussed above, is only capable of
decrypting one type of signal encryption, thereby
limiting the user/viewer to viewing signals capable of
being decrypted with that particular smart card (e.g.
signals only from one satellite).
Accordingly, there exists a need in the art for a
system/method for allowing a user at the user's residence
to simultaneously receive a plurality of differently
encrypted or scrambled satellite television broadcast
signals ~rom different satellites, choose a particular
signal for viewing, and decrypt the selected signal for
subsequent viewing. There also exists a need in the art
in such a system for a converter box provided with a
plurality o~ different simultaneously received removable
decrypting cards which allow the user to decrypt signals
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differently encrypted signals from multiple satellites
(each satellite, for example, using a different
encryption technique or algorithm), and interchange the
removable cards with different decryption cards at the
5 user~s desire.
It i8 a purpose of this invention to fulfill the
above-described needs, as well as other needs apparent to
the skilled artisan from the following detailed
description of this invention.
SUM~RY OF THE INVENTION
Generally speaking, this invention fulfills the
above-described needs in the art by providing a home
satellite television receiving system and corresponding
method for receiving and decrypting signals transmitted
15 from a plurality of different satellites, the system
comprising:
an antenna system for simultaneously receiving first
and second encrypted television signals from first and
second satellites respectively, said first and second
20 signals having different types of encryption;
a switch for allowing a user or viewer to select one
of the first and second signals for viewing; and
a decrypting device simultaneously housing first and
second removable smart cards, the first smart card
25 including a memory for storing a first decrypting
algorithm for decrypting the received first signal havlng
the first encryption, and the second smart card including
-~ a second decrypting algorithm for decrypting the received
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second signal having the second encryption whereby the
~ignal selected ~or viewing by the user or viewer,
whether the first signal or the second signal, is
decrypted using the appropriate smart card and thereafter
forwarded ~or viewing.
This invention further ful~ills the above-described
needs in the art by providing a multiple beam array
antenna system for receiving/transmitting signals of
different polarity, the system comprising:
means for receiving/transmitting both linearly and
circularly polarized signals at substantially the same
frequency;
means for receiving/transmitting one of: (i) right-
handed circularly polarized signals; (ii) le~t-handed
circularly polarized signals; and (iii) linearly
polarized signals; and
the multiple beam array antenna system being used in
conjunction with a decrypting device simultaneously
housing at least one smart card including a memory for
decrypting a received signal.
IN THE DRAWINGS
Figure 1 is a block diagram of certain components
making up the system/method according to an embodiment of
this invention.
Figure 2 is a block diagram illustrating a parabolic
antenna system including a plurality of antennas in
combination with the input signal interface o~ Figure 1.
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Figure 3 is a block diagram of the RF tuner,
demodulator, and error correction block o~ Figure 1.
Figure 4 is a block diagram of the digital data
decryp~ion and descrambling block of Figure 1.
~ 5 Figures 5(a) and 5(b) are top elevational and side
elevational views of one of the decrypting smart cards to
be inserted into the decrypting/descrambling block of
Figures 1 and 4.
Figure 6 is a block diagram of the decompression
block of Figure 1.
Figure 7 is a block diagram of the video and audio
modulators of Figure 1.
Figure 8 is a block diagram o~ the controller o~
Figure 1.
Figure 9 is a block diagram o~ the communications
block of Figure 1.
Figure lO is a side elevational view, including
remote control, of the control and status device o~
Figure 1.
Figure 11 is an exploded perspective view of a
multibeam array antenna which is in communication with
the input signal interface of Figure 1 according to
certain embodiments o~ this invention, this antenna
simultaneously receiving a plurality of differently
25 encrypted signals from different satellites.
Figure 12 is a side cross-sectional view of a single
antenna element of the Figure 11 array coupled to a
combining waveguide.
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Figure 13 is a front or rear cross-sectional view of
a subarray of Figure 12 antenna elements positioned
adjacent their corresponding combining subarray
waveguide.
Figure 14 is a top elevational view of the plurality
of antenna elements making up the plurality of subarrays
of the above-identified array antenna.
Figure 15 is a schematic diagram of the Figure ll-14
antenna illustrating the different subarrays, combining
waveguides, low noise amplifiers, electromagnetic lenses,
and satellite selection output matrix block.
DETAILED DESCRIPTION OF
CERTAIN EMBODIMENTS OF THIS INVEMTION
Referring now more particularly to the accompanying
15 drawings in which like re~erence numerals indicate like
parts throughout the several views.
Figure l is a block diagram of a satellite
television receiving system for receiving, selecting,
decrypting, and descrambling signals transmltted from a
20 plurality of di~erent satellite~ 18 according to an
embodiment of this invention. The system includes input
signal inter~ace 3, radio frequency (RF) tuner,
demodulator, and forward error correction system 5,
digital data decrypting and descrambling device 7,
25 controller 9, communications block ll, control and status
device 13 including a remote control 105, MPEG 2
decompression system 15, and video and audio modulators
17 The above-listed components are made up of hardware
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in certain embodiments, but may be made up of software
according to certain alternative embodiments.
Referring now to Figures 1-2, signals 19 input to
input signal interface 3 are a plurality of digitally
5 modulated radio frequency (RF) carriers ~orwarded ~rom
antenna system 21. Antenna system 21 may either be a
plurality of parabolic antennas (see Figure 2) or a
multibeam array antenna (see Figure 11), both o~ which
are designed to simultaneously receive a plurality o~
o di~erent signals ~rom di~erent satellites 18, each
satellite using different encryption in many instances.
For example, a multibeam array antenna system 21 (see
Figure 11) may simultaneously receive right-hand
circularly polarized, left-hand circularly polarized, and
15 linearly polarized downlink signals ~rom ~irst, second,
and third satellites 18 respectively, each having
di~ferent encryption.
Signals 19 output ~rom antenna system 21 are at a
first intermediate frequency (IF) from a plurality o~ low
20 noise block down converters (LNBs) located within antenna
system 21. The multibeam array antenna or parabolic
antennas of system 21 is/are directed toward a plurality
of direct-to-home (DTH) direct broadcast satellites (DBS)
or any other conventional satellite. LNB DC control 23
and first intermediate frequency (IF) input signal switch
25 are included in input signal inter~ace 3, with switch
25 functioning to select (in accordance with
instructions) one of the plurality of IF signals received
~rom antenna system 21 ~or subsequent forwarding to the
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decrypting and descrambling system. Switch 25 is
controlled by way of bus 27 via controller 9 and control
and statu5 station 13 so that the user may scan through
the received DBS signals using remote control 105
together with the user's televi8ion (or display screen)
and select the desired one for viewing.
DC power supply 29 functions to power the L~3 DC
control 23 which in turn allows IF input switch 25 to be
operated. The selected IF signal 31 received from
antenna system 21 is forwarded from input signal
interface 3 to block 5 for conventional radio frequency
(RF) tuning, demodulation, and forward error correction
(FEC).
As shown in Figure 3, output 31 of input siynal
interface 3 reaches block 5 and ~irst enters RF tuner 33.
Tuner 33 is of conventional nature and functions to
forward the selected satellite broadcast channel from the
IF signal to demodulator 35. Tuner 33 is instructed by
way of bus 27 as to which ~h~nn~l has been selected by
the user/viewer via remote control 105, for example, at
station 13. The output of tuner 33 is forwarded to
demodulator 35 which samples the signal to demodulate
therefrom in a known manner. Any type of conventional
and compatible modulation and demodulation may be used.
The output of demodulator 35 is forwarded to forward
error correction (FEC) device 37, which is conventional
in nature. FEC device 37 employs the adding of
systematic redundancy at the transmit end of the
communication length such that errors caused by the
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transmission medium can be corrected by way of a known
decoding algorithm. Any conventional type of known FEC
may be utilized. After being forward error corrected,
data and clock output 39 of block 5 is forwarded to
decrypting and descrambling station 7.
Decrypting and descrambling station 7 receives
output 39 from FEC device 37, this output being a high
speed digital stream which is subse~uently decrypted and
descrambled in block 7. Decryption, the inverse of
encryption, is the process whereby information is
recovered from the publicly transmitted satellite
downlink signal formatted digitally through the use of an
encryption algorithm, and a selected key, from a set of
possible keys appropriate for the particular encryption
algorithm. In such a mAnner, confidential information
controlling the descrambling process can be passed or
transmitted by way of open channels provided that
security is maintained for the specifics of the
encryption algorithm and keys. Encryption systems can be
20 made robust to an arbitrarily high level of security
through increasing cleverness and complexity.
Descrambling, on the other hand, is the process used to
render the video image useless to an unauthorized viewer.
This may be accomplished in many conventional ways within
25 the transmission and reconstruction of video information.
In block 7, descrambling of the signal is a
continuous process performed upon the video data frames
received from FEC 37 that restores original images, this
descrambling process being under the functional control
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of information which may be resident within smart cards
41 (in certain embodiments) removably placed within
receptacles or storage slots 43.
The encryption (and decryption) key and algorithm
information stored within smart cards 41 may be
periodically updatable through the transmitted encrypted
data channel. Both the scrambled video data channels and
the encrypted data channel are contained within the
satellite transmitted MPEG transport layer data stream of
o the transmitted signal according to certain embodiments.
Decryption functions reside within smart cards 41 while
descrambling functional elements may reside within smart
cards 41 and/or external elements.
Block 7 includes high speed digital data interface
45 and a plurality of smart card receptacles 43 coupled
by way of communication links/interfares 49, each
receptacle 43 being conventional in nature and adapted to
removably receive a single smart card 41 so that a
plurality of different decryption descrambling algorithms
20 may be stored within block 7, each card 41 storing a
different such algorithm appropriate for use in
decrypting descrambling a particularly encrypted
scrambled signal transmitted by way of satellite
downlink.
The channel selected for viewing in block 5 is
interfaced with the appropriate decrypting descrambling
smart card by way of high speed digital data interface 45
so that the encryption scrambling technique of the
selected signal corresponds to the decryption
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descrambling algorithm and/or key stored on the accessed
smart card 41. In such a manner, the correct decryption
descrambling algorithm can be applied to the encrypted
scrambled selected signal. The smart card 41 stored in
each receptacle 43 in block 7 stores a different
decryption algorithm 80 that the number o~ stored
decrypting descrambling algorithms in block 7 is a
function of the number of receptacles 43. For example,
if three receptacles 43 are provided, then three
different decrypting descrambling algorithms may be
stored and accessed within block 7 by way o~ three smart
cards 41 in view of the ~act that each receptacle 43
removably receives a single smart card 41.
After the selected signal and channel has been
matched with the appropriate decrypting algorithm by way
of interface 45, block 7 functions to decrypt and
descramble the selected data in a known manner.
Interface 45 and receptacles 43 are controlled by way of
control and status data bus 27. Inter~ace 45 includes a
20 switch and interfacing circuits to control the
distribution of digital data streams and clock data as
will be appreciated by those of skill in the art.
Communication links or interfaces 49 allow interface 45
to communicate with receptacles 43 thereby interfacing
25 the high speed digital data and clock loop interfaces to
receptacles 43 and the information stored on smart cards
4l therein thereby linking the selected encrypted
scrambled data with the corresponding smart card 41 for
decrypting and/or descrambling.
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After descrambling and decryption, output 51
(descrambled and decrypted) of block 7 ls forwarded to
conventional MPEG 2 decompression block 15. MPEG 2
decompression statlon 15 i8 shown in more detail in
5 Figure 6. Block 15 includes conventional MPEG 2 circuits
53, video RAM 55, audio RAM 57, MPEG audio unit 59, and
MPEG video unit 61, all of which are conventional in
nature. Output 63 of MPEG 2 circuits 53 is forwarded as
a wideband data output while outputs 65 and 67 of MPEG
o video and MPEG audio respectively are forwarded to video
and audio modulators 17 (~ee Figure 7) so that the
decompressed signals may be further processed for
viewing.
Video and audio modulator block 17 is shown in
15 detail in Figure 7. This block include~ audio digital to
analog converter 69, NTSC video modulators 71, and phase
alternation line (PAL) block 73 The outputs of digital
to analog converter 69, NTSC (National Television Systems
Committee) video modulators 71, and PAL 73 are forwarded
20 to the viewer's television set or display for viewing by
the viewer/user.
Referring now to Figures 5(a) and 5(b), top and side
elevational views of a smart card 41 respectively, it may
be seen that each removable smart card 41 is
25 substantially planar in nature and includes area 75 for
electronics and area 77 ~or connectors. ~ conventional
PCMCIA or ISO 7816, for example, may be located in area
77 for communicating with interface 45 by way o~
receptacle 43 and communication link/inter~ace 49. The
14
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electroniCs area 75 on each card 41 may be formed in a
known mAnne~ so as to include the required decryption
algorithm circuitry.
Flgure 8 is a block diagram of controller 9. As
shown, controller 9 includes a typical microprocessor 81,
RAM 83, EPROM 85, EEPROM 87, and interface system 89 for
allowing the memories to communicate with microprocessor
81. Microprocessor 81 is in communication with bus 27 so
that controller 9 may communicate with input signal
interface 3, block 5, descrambler and decrypter 7, MPEG 2
decompressor 15, control and status block 13, and
communications block ll. Input signal switching in
interface 3 by way of switch 25 is accomplished by use of
control signals originating from controller 9 according
to certain embodiments. When the user at control and
status station 13 desires to view a particular channel,
controller 9 outputs data to interface 3 in order to
instruct interface 3 and switch 25 therein to select the
particular signal/satellite for viewing and subsequent
20 forwarding to block 5 and block 7. Each of the memories
and microprocessor in controller 9 as shown in Figure 8
are conventional in nature and may be purchased
commercially (or may be implemented using software).
Figure 9 is a block diagram of communications block
ll which includes modem 93 (conventional in nature) and
UART 95, also conventional in nature. Modem 93 and UART
95 are in communication with bus 27 as well as outside
communications channels and devices by way of outputs 97.
Communications block ll by way of modem 93 and UART 95
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permit the set top box of this invention to communicate
with other electrical components outside of the system
such as phone lines, etc., by way o~ outputs 97.
CommunicatiOnS block 11 optionally may be u~ed to receive
remote control signals from the user.
Figure 10 is a side elevational schematic view of
control and status unit 13 and bus 27. Control and
status unit 13 includes a conventional box housing and
including front panel controllers 99, ~ront panel status
o indicator (liquid crystal display, ~or example) 101, and
remote control IR or RF receiver 103. Remote control 105
i~ used to instruct the set top box system by way of
wireless link 107 of instructions from the user. By way
of remote control 105, the user may select particular
15 satellites and then ~h~nn~ls for viewing. Remote control
105 may be of the infrared (IR) or radio frequency (RF)
wireless type. Display 101 may indicate, ~or example,
which channel is being currently viewed by the viewer and
from which satellite. Front panel controllers or control
20 switches 99 are provided so as to allow the user to
manually select different channels or satellites instead
of using remote control 105 as discussed above.
Figure 11 is a perspective exploded view o~ a
multibeam array antenna for simultaneously receiving
25 signals (RH, LH, and linear ~or example) ~rom different
satellites. The multibeam array antenna shown in Figure
11 is more fully described in U.S. Serial No. 08/299,376,
the disclosure o~ which is incorporated herein by
reference. This array antenna system or a plurality of
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parabolic antennas (see Figure 2) may make up antenna
system 21 which is in communication with the set top box
of this invention.
As shown, Figure 11 illustrates the multiple beam
5 array antenna system adapted to receive signals in about
the 10.70 - 12.75 GHz range. The antenna array portion
includes a plurality of helical subarrays made up of
antenna elements 1, element or antenna mounting plate
203, signal combining waveguides 205 (one waveguide 205
o per subarray), and protective housing or radome 8.
Housing 8 provides environmental protection to elements 1
and is transparent to frequency fields existing at the
antenna aperture. Figure 12 shows a single antenna
element 1 connected to mounting plate 203 and signal
15 summing or combining subarray waveguide 205. Each
antenna element 1 includes tapered dielectric rod or
mandrel 213 which is made of an injection moldable
plastic such as Delrin. A single wire or ~oil conductor
215 is wound around dielectric mandel 213 in a helical
20 fashion. Conductor 15 performs the primary electrical
receiving/transmitting function of each antenna element
1. Each antenna element 1 is provided in a cup aperture
211 milled out of plate 203. Mandrel 213 of each element
1 includes cylindrical extension 225 protruding from its
25 base so as to allow each mandrel to be affixed to plate
203 via an aperture in the plate, thereby allowing output
probe 221 (which i8 attached to conductor 215) to extend
into the confines of rectangular signal summing waveguide
205.
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As shown in Figure 14, the signal receiving antenna
array of certain embodiments is made up of a plurality of
subarrays, each subarray having its own waveguide 205.
Each subarray may be made up of four similarly wound
(either right-handed circularly polarized or left-handed
circularly polarized) helical elements 1. The antenna
system may include twenty-four separate non-symmetrical
subarrays in order to form a fan-shaped beam, the twenty-
four subarrays being made up of twelve right-handed
o circularly polarized subarrays and tweleve left-handed
circularly polarized subarrays interleaved with one
another. The provision o~ both right and left-handed
circularly polarized subarrays allows the illustrated
phased array antenna system to receive signals from
dif~erent satellites emitting either right or left-handed
circularly polarized signals, or linearly polarized
(horizontal or vertical) signals. Cover plate 233 seals
the rear or lens side of waveguides 205. Apertures in
plate 233 through which probes 231 extend are ~illed with
dielectric material 235.
Figure 15 is a schematic of the multi-beam array
antenna according to certain embodiments. As shown, the
signal is received by either the right-handed or left-
handed subarray elements 1 or both. Thereafter, the
signals received by the elements are sum~ed in the
appropriate waveguide 205, the combined signals of each
subarray then being sent to a low noise amplifier 239.
After amplification, the signals from the left-handed
subarrays are sent to electromagnetic lens 555 while the
18
,
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signals from the right-handed helical subarrays are sent
to electromagnetic lens 553. Satellite selection matrix
output block 69 in connection with the set top box
discussed above then allows the user to select from which
5 satellite(s) he wishes to receive signals. The outputs
from both lenses 553 and 555 may be tapped so as to
result in the receiving of a signal from a satellite
havlng linear polarization. Ports 663 ~input) and 665
~output) of the lenses may be designed so that the
o angular increments of beam scans of each lens is about
4~. By combining the use of lenses 553 and 555, the user
may receive satellite signals from anywhere in the
antenna's scanning range o~ either lens in any
polarization sense. The scanning capability of the
15 system is bounded by the capability of the lenses and the
array. Lenses 553 and 555 are time-delay devices
designed to scan on the basis of optical path lengths,
their radiated or scanned beams being substantially fixed
in space. The constrained lenses also include a
plurality of radiators to collect energy at the lens back
face and to re-radiate energy from the front face. In
accordance with the described lens design, the lenses in
combination with the antenna system allow the system to
select a single beam or a group of beams for reception
for home satellite television viewing. Right-handed
circularly polarized satellite signals, left-handed
~ circularly polarized satellite signals, and linearly
polarized satellite signals within the scanned field of
view may be accessed either individually or in groups.
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Thus, either a single or a plurality of such satellite
signals may be simultaneously received and accessed at
substantially the same frequency. As discussed above,
the antenna array system of Figures 11-15 is used in
conjunction with the set top box of Figures 1-10.
once given the above disclosure, therefore, various
other modifications, features, or improvements will
become apparent to the skilled artisan. Such other
features, modifications, and improvements are thus
considered a part of this invention. The scope of which
is to be determined by the following claims.
