(12) United States Patent
`Williams
`
`USOO6493873B1
`(10) Patent No.:
`US 6,493,873 B1
`(45) Date of Patent:
`*Dec. 10, 2002
`
`(54) TRANSMODULATOR WITH DYNAMICALLY
`SELECTABLE CHANNELS
`
`(75) Inventor: Jim C. Williams, Anaheim, CA (US)
`
`(73) ASSignee: th. ters Corporation, El
`
`JP
`JP
`JP
`JP
`JP
`JP
`WO
`
`60-182887
`2-13030
`8-242436
`8-274711
`8-294.108
`8-3173.71
`WO 97/O1931
`
`9/1985
`1/1990
`3/1995
`3/1995
`4/1995
`5/1995
`1/1997
`
`(*) Notice:
`
`-
`
`0
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`This patent is Subject to a terminal dis-
`claimer.
`
`(21) Appl. No.: 09/008,879
`(22) Filed:
`Jan. 20, 1998
`Related U.S. Application Data
`(63) Continuation-in-part of application No. 08/787,336, filed on
`Jan. 27, 1997.
`
`(51) Int. CI.7 - - - - - - - - - - - - - - - - - - - - - - - - - - - HO)4N 7/18: HO4N 7/173
`
`(56)
`
`(52) U.S. Cl. ............................. 725/78; 725/71; 725/95;
`725/98; 725/118
`(58) Field of Search .............................. 725/64, 71, 72,
`725/95, 98, 78,118
`References Cited
`U.S. PATENT DOCUMENTS
`3,833,757 A
`9/1974 Kirk et al. ................... 178/5.6
`3,935,534 A
`1/1976 Lewis et al. ................ 325/308
`4,145,720 A 3/1979 Weintraub et al. .......... 358/194
`(List continued on next
`)
`page.
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`EP
`GB
`JP
`
`27 14774
`O 144 770
`O 73O 383 A2
`2 288 714
`56-471.83
`
`10/1978
`6/1985
`9/1996
`10/1995
`4/1981
`
`OTHER PUBLICATIONS
`
`Cellular Vision USA, Inc., CV Cellular Vision 3,333,000
`Shares Cellular Vision USA, Inc. Common Stock, Prospec
`tus dated Feb. 8, 1996, pp. 3-5, 8-14, 21-42.
`Darcie, T.E., “Subcarrier Multiplexing for Lightwave Net
`works and Video Distribution Systems,” IEEE Journal On
`Selected Areas in Communications, 8(7): 1240–1248 (Sep.,
`1990).
`
`(List continued on next page.)
`Primary Examiner Bhavesh Mehta
`ASSistant Examiner Kieu-Oanh Bui
`(74) Attorney, Agent, or Firm John A. Crook; Michael W.
`Sales
`
`(57)
`
`ABSTRACT
`
`A System for redistributing a broadband audio-visual-data
`signal to a multiplicity of receiver units within a multiple
`dwelling unit (MDU) includes a main receiving antenna that
`receives a broadband Video/audio/data Signal having a num
`ber of individual program multiplex signals therein and a
`transmodulator device that transmodulates a Selected Subset
`of the individual program multiplex Signals associated with
`the broadband signal from a first modulation Scheme to a
`Second modulation Scheme. The transmodulated Signals are
`broadcast over a cable network, along with terrestrial
`signals, to individual receiver units at the MDU. The
`receiver units Send requests for user-Selected ones of the
`individual program multiplex Signals to the transmodulator
`device, demodulate the transmodulated and/or terrestrial
`Signals and provide user-specified channels to television Sets
`for display.
`
`25 Claims, 7 Drawing Sheets
`
`54
`
`56
`
`58
`
`Pocketizer
`
`Cable
`Encoder
`
`Upconverter
`
`RHCP
`
`SO
`
`
`
`
`
`
`
`a.
`
`Tronsmodulator
`Control Panet
`
`Trunsmoductor
`Control Unit
`
`Upconverter
`
`
`
`1 circuit
`4 circuits
`4 circuits
`4 circuits
`4 circuits
`4 circuits
`4 circuits
`3 circuits
`
`Upconverter
`
`
`
`Demoductor
`decoder
`
`1
`
`Comcast, Ex. 1220
`
`

`

`US 6,493.873 B1
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`5/1984 Lovett ......................... 358/86
`4,450,477 A
`4,475,123. A 10/1984 Dumbauld et al.
`. 358/114
`4,475.242 A 10/1984 Rafal et al. ...
`... 455/3
`4,592,093 A 5/1986 Ouchi et al.
`... 455/4
`4,608,710 A 8/1986 Sugiura ........
`... 455/4
`4,695,880 A 9/1987 Johnson et al.
`... 358/86
`4,709,418 A 11/1987 Fox et al. ..
`... 455/612
`4,710,956 A 12/1987 Rast .............
`... 380/20
`4,710,972 A 12/1987 Hayashi et al.
`... 455/179
`4,747,160 A 5/1988 Bossard ........
`... 455/33
`4,805,014 A 2/1989 Sahara et al. ....
`... 358/86
`4,823,386 A 4f1989 Dumbauld et al.
`380/13
`4,901,367 A 2/1990 Nicholson et al. ..
`... 455/5
`4,916,532 A 4/1990 Streck et al. ....
`358/83
`4,930,120 A 5/1990 Baxter et al. .
`... 370/73
`4,935,924 A 6/1990 Baxter ..........
`... 370/73
`4.959,862 A 9/1990 Davidov et al.
`... 380/10
`4,975,771. A 12/1990 Kassatly .......
`... 358/146
`5,012,350 A 4/1991 Streck et al. .
`... 358/335
`5,023.931 A 6/1991 Streck et al. ................. 455/21
`5,027,430 A 6/1991 Yamauchi et al.
`... 358/142
`5,029,003 A 7/1991 Jonnalagadda ...
`5,038,402 A 8/1991 Robbins ........................ 455/3
`5,045.948 A 9/1991 Streck et al. .
`358/1941
`5,073.930 A 12/1991 Green et al. ..
`380/10
`5,077.607 A 12/1991 Johnson et al.
`. 358/86
`5,101,499 A 3/1992 Streck et al. ....
`... 455/4
`5,105.268 A 4/1992 Yamanouchi et al.
`... 358/84
`5,125,100 A 6/1992 Katznelson ......
`... 455/6.1
`5,136,411 A 8/1992 Paik et al. .................. 359/125
`5,155,591. A 10/1992 Wachob
`5,168,356 A 12/1992 Acampora et al.
`5,173,775 A 12/1992 Walker ....................... 358/141
`5,200,823 A 4/1993 Yoneda et al. .............. 358/146
`5,214.501 A 5/1993 Cavallerano et al.
`... 358/12
`5,220,420 A
`6/1993 Hoarty et al.................. SSS.
`5,231,494. A
`7/1993 Wachob ...................... 358,146
`5,257,396 A 10/1993 Auld et al. .................... 455/2
`5,276,904 A
`1/1994 Mutzig et al.
`5,283,639 A 2/1994 Each et al. .................... 348/6
`5,293,633 A 3/1994 Robbins
`... 455/3.1
`5,394,559 A 2/1995 Hemmie et al. ............. 455/5.1
`5,408.259 A 4/1995 Warwick et al. ............... 348/6
`
`
`
`5,412,720 A 5/1995 Hoarty ........................ 380/15
`5,450,392 A 9/1995 Waltrich ........................ 370/6
`5,475,498 A 12/1995 Radice ....................... 358/335
`5,483,663 A 1/1996 Tawi
`5,483,686 A
`1/1996 Saka et al. ............... 455/182.2
`5,504.816. A 4/1996 Hamilton et al. ............. 380/20
`5,512.936 A 4/1996 Burton et al. ................. 348/11
`5,521,631 A 5/1996 Budow et al.
`5,572,517. A 11/1996 Safadi ......................... 370/50
`5,742,640 A 4/1998 Haou et al.
`5,760,819 A 6/1998 Sklar et al.
`5,787,335 A
`7/1998 Novak
`5,790,175 A
`8/1998 Sklar et al.
`5.835,128 A 11/1998 Macdonald et al.
`5,920,626 A * 7/1999 Durden et al. ................ 380/10
`5,970,386 A * 10/1999 Williams ..........
`. 455/4.1
`6,104,908 A * 8/2000 Schaffner et al. ............ 455/3.2
`6,134,419 A * 10/2000 Williams .................... 455/6.2
`
`OTHER PUBLICATIONS
`
`European Telecommunication Standard, "Digital broadcast
`ing Systems for television, Sound and data Services; Satellite
`Master Antenna Television (SMATV) distribution systems.”
`TM 1285 Revision 1, Draft pr ETS 300 473, Nov., 1994,
`Source: EBU/ETSI JTC, Reference: DE/JTC-DVB-7-1,
`European Telecommunications Standard Institute, European
`Broadcasting Uni
`F
`3-25 (1994
`roadcasung Union trance, pp.
`(1994).
`Lieberman, D., “Wideband Distribution Equipment for
`Cable Television (CATV).” Automatic Electric Technical J.,
`12(4):160-171 (Oct., 1970).
`Olshansky et al., “Subcarrier Multiplexed Coherent Light
`wave Systems for Video Distribution.” IEEE Journal on
`Selected Areas in Communications, 8(7): 1268–1275 (Sep.,
`1990).
`66
`Terry, J. "Alternative Technologies and Delivery Systems
`for Broadband ISDN Access: Rapid deployment of B-ISDN
`depends upon collaboration among potential transport,
`delivery, and Service providers-especially for on-demand
`video,” IEEE Communications Magazine, pp. 58-64 (Aug.,
`1992).
`
`* cited by examiner
`
`2
`
`

`

`U.S. Patent
`US. Patent
`
`US 6,493,873 B1
`US 6,493,873 B1
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`U.S. Patent
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`Dec. 10, 2002
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`Sheet 2 of 7
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`US 6,493,873 B1
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`U.S. Patent
`US. Patent
`
`Dec. 10, 2002
`Dec. 10, 2002
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`Sheet 3 of 7
`Sheet 3 0f 7
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`US 6,493,873 B1
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`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 4 of 7
`
`US 6,493,873 B1
`
`FROM TUNER 54
`
`QPSK SYMBOLS
`
`QPSKDEMODULATOR /
`
`DATA BIT STREAM
`
`CONVOLUTIONAL
`DECODER
`
`82
`
`147 BYTE INTERLEAVED
`DATA PACKETS
`
`SYNC &
`DE-NTERLEAVER
`
`84
`
`16 R-S CODE BYTES
`
`130 P-MDATABYTES
`
`R-S DECODER
`
`88
`
`89
`
`130 P-M DATA BYTES
`
`TO PACKETIZER 58
`
`F. G. A.
`
`6
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 5 of 7
`
`US 6,493,873 B1
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`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 6 of 7
`
`US 6,493,873 B1
`
`60
`
`FROMPACKETIZER 58
`
`
`
`
`
`
`
`
`
`
`
`SCRAMBLER
`
`R-S ENCODER
`
`NTERLEAVER
`
`BYTE TO
`M-UPLE
`
`DIFFERENTIAL
`ENCODER
`
`SORT RAISED
`COSINE
`FILTER
`
`1 OO
`
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`MODULATER
`
`102
`
`TO UPCONVERTER 62
`
`F. G. 6
`
`8
`
`

`

`U.S. Patent
`
`Dec. 10, 2002
`
`Sheet 7 of 7
`
`US 6,493,873 B1
`
`FROM CABLE NETWORK26
`
`26
`
`DOWN-CONVERTER
`& TUNER
`
`110
`
`MCNS
`INTERFACE
`
`107
`
`105
`
`is
`
`CONTROLLER
`
`controller REast
`
`...
`115
`
`
`
`
`
`PACKETIZER
`
`
`
`SPLTTER
`
`TRANSPORT
`DECODER
`
`
`
`DEMULTIPLEXER
`
`
`
`DATA
`PROCESSOR
`
`ANALOGVDEO
`126
`
`F. G. 7
`
`
`
`
`
`
`
`9
`
`

`

`1
`TRANSMODULATOR WITH DYNAMICALLY
`SELECTABLE CHANNELS
`
`US 6,493,873 B1
`
`15
`
`2
`in-operation uses an uplink Signal having 16 RHCP tran
`sponder Signals and 16 LHCP transponder Signals modu
`lated onto frequency bands between about 17.2 GHz, and
`about 17.7 GHz. Each of these 32 transponder signals is
`program-multiplexed to include digital data packets associ
`ated with e.g. about five to eight or more individual A-V
`programs, Such as television channels, and is modulated
`according to a quaternary phase shift keying (QPSK) modu
`lation Scheme. The Satellites associated with this System
`shift the uplink transponder Signals to carrier frequencies
`ranging from approximately 12.2 GHz to approximately
`12.7 GHz and transmit these frequency-shifted transponder
`Signals back to earth for reception at each of a plurality of
`individual receiver units.
`At the individual receiver units, a receiving antenna,
`typically comprising a parabolic dish antenna, is pointed in
`the general direction of the transmitting Satellite (or other
`transmitting location) to receive the broadband QPSK
`modulated multiplex of A-V Signals. Typically, Such anten
`nas include a low noise block (LNB) which amplifies, filters
`and shifts the incoming Signal to an intermediate frequency
`band, such as L-band (between about 1.0 GHz and 2.0 GHz).
`The representative System, in particular, Shifts the Satellite
`signal to the frequency band between about 950 MHz and
`about 1450 MHZ.
`Typically, only the RHCP transponder signals or the
`LHCP transponder signals are mixed down to L-band,
`depending on which particular A-V channel a user is view
`ing. However, in systems having a two-channel LNB, both
`the RHCP and the LHCP transponder signals may be indi
`vidually shifted down to a 500 MHz portion of L-band (e.g.,
`between 950 MHz and 1450 MHz) and provided, via sepa
`rate lines, to a set-top box or other integrated receiver and
`detector (IRD) associated with the receiver unit. At the IRD,
`an A-V program associated with a particular channel within
`one of the program-multiplexed transponder Signals is
`decoded and provided to a television or other presentation or
`processing device for display and/or for processing of trans
`mitted data, audio output, etc. However, because cable lines
`are inherently frequency limited, typical cables used at
`receiver sites (such as RG-6 and RG-59) are not capable of
`Simultaneously transmitting all of the received Satellite
`signals (1000 MHz) along with standard CATV signals to
`the IRD.
`Furthermore, the receiving antennas or dishes associated
`with land-based or satellite-based wireless signal distribu
`tion Systems are typically large and cumberSome. For
`example, C-band Satellite dishes are generally in the range
`of four to five feet in diameter and, therefore, require a large
`amount of operating Space. As a result, it can be difficult, if
`not practically impossible, to install a receiving antenna for
`each individual unit within a multiple dwelling unit (MDU),
`Such as an apartment, condominium or townhome complex.
`Reception of a particular Satellite Signal is made even more
`difficult in MDUs when, as is generally the case, some of the
`individual dwelling units therein do not have any walls or
`outside exposure facing the direction in which the receiving
`antenna must be pointed, or these dwelling units are Shad
`owed by Surrounding buildings or other obstructions.
`In the past, these disadvantages have been overcome by
`placing one or more receiving antennas on, for example, the
`roof of an MDU and then running cable to each of the
`individual dwelling units. For example, a System for redis
`tributing a single, off-air signal to multiple buildings in a
`Small geographic area is disclosed in Japanese Patent Docu
`ment No. 56-47183. However, common L-band multi-user
`distribution Solutions typically used to Support Single dish
`
`25
`
`RELATED APPLICATION
`This application is a continuation-in-part of U.S. patent
`application Ser. No. 08/787,336, entitled “Transmodulated
`Broadcast Delivery System for use in Multiple Dwelling
`Units, filed Jan. 27, 1997.
`BACKGROUND OF THE INVENTION
`(a) Field of the Invention
`The present invention relates generally to signal distribu
`tion Systems and, more particularly, to audio/visual/data
`Signal distribution Systems that distribute Satellite signals
`typically in conjunction with Standard terrestrial and/or
`cable Signals to a plurality of individual receivers within one
`or more multiple dwelling units.
`(b) Description of Related Art
`Audio/visual/data (A-V) signal distribution Systems gen
`erally rely on either a cable network or on free-space
`propagation for delivering A-V signals, Such as television
`signals, to individual users or subscribers. Cable-based A-V
`Signal distribution Systems transmit one or more individual
`A-V Signals or “channels' over wire, while free-space
`propagation Systems transmit one or more channels over
`the-air, i.e., in a wireleSS manner. Most large-scale cable and
`wireleSS Signal distribution Systems broadcast a broadband
`A-V signal having a plurality of individual A-V signals
`modulated onto one or more carrier frequencies within a
`discernable frequency band.
`Some wireleSS Signal distribution Systems use one or more
`geosynchronous Satellites to broadcast a broadband A-V
`Signal to receiving units within a large geographic area while
`35
`other wireleSS Systems are land-based, using one or more
`land-based transmitters to broadcast to individual receiver
`units within Smaller geographic areas or cells. A Satellite
`A-V signal distribution System generally includes an earth
`Station that compiles a number of individual A-V programs
`into a broadband Signal, modulates a carrier frequency band
`with the broadband Signal and then transmits (uplinks) the
`modulated Signal to one or more geosynchronous Satellites.
`The Satellites amplify the received Signals, shift the Signals
`to different carrier frequency bands and transmit (downlink)
`the frequency shifted Signals to earth for reception at indi
`vidual receiving units.
`The uplink and downlink broadband Signals of analog
`Satellite Systems are usually divided into a plurality of
`transponder Signals, each typically containing a single ana
`log Signal. For example, analog Satellite Systems operating
`in the so-called “C-band, i.e., between 3.7 GHz and 4.2
`GHZ, may broadcast a plurality of transponder Signals, each
`including a single frequency modulated analog T.V. channel.
`In current digital Satellite Systems, each transponder typi
`cally contains a number of individual channels multiplexed
`into a single data Stream, commonly referred to as a program
`multiplex.
`Satellite Systems may also broadcast a Set of transponder
`Signals at multiple polarizations, for example, at a right-hand
`circular polarization (RHCP) and at a left-hand circular
`polarization (LHCP), within the band of carrier frequencies
`associated with the satellite, effectively doubling the number
`of channels broadcast by the System.
`Satellite Signal distribution Systems exist for many fre
`quency bands, including the So-called "Ku-band.” One
`known Ku-band direct-to-home Satellite System now
`
`40
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`45
`
`50
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`55
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`60
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`65
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`

`

`US 6,493,873 B1
`
`5
`
`25
`
`3
`antenna Systems are fraught with installation and mainte
`nance problems. For example, Significant roll-off or degra
`dation of the television signals may occur in cable Systems
`due to the poor high frequency propagation properties of
`Standard cable lines especially at and above L-band. Broad
`casting a received broadband A-V Signal Over an existing
`cable network at lower carrier frequencies may prevent the
`use of that network for other A-V signals, Such as Standard
`cable, CATV, UHF and VHF television signals, or may
`require that the Some of the broadband Signals or existing
`cable Signals be eliminated due to the bandwidth restrictions
`of the cable network.
`One System proposed by the European Telecommunica
`tions Standards Institute (ETSI) in the area of Satellite
`Master Antenna Television (SMATV) receives a QPSK
`15
`modulated Satellite television signal (which may be com
`bined with terrestrial TV signals) and remodulates this signal
`according to a 64 quadrature amplitude modulation (64
`QAM) technique. The SMATV system then sends this
`remodulated Signal out over cable to one or more adjacent
`buildings. Likewise, U.S. Pat. No. 5,173,775 discloses a
`System that remodulates data portions of a Satellite television
`Signal from one modulation Scheme to another, Such as from
`FM to AM, for retransmission to Subscribers. However,
`these Systems do not Specifically demonstrate how to propa
`gate remodulated Satellite signals and existing cable or
`terrestrial Signals on the same cable line or other transmis
`Sion channel in an efficient manner or demonstrate how to
`remodulate and broadcast a large number of transponder
`Signals associated with one or more Satellites over the same
`cable line or other transmission channel to one or more
`adjacent buildings.
`The above-identified parent application discloses a signal
`redistribution System that transmodulates each of, for
`example, 32 received Satellite transponder Signals into a
`different modulation Scheme and transmits each of these
`transmodulated Signals, along with Standard terrestrial
`signals, to each of a set of receivers within an MDU. The
`transmodulator disclosed in this application includes a sepa
`rate channel having a Satellite Signal demodulator coupled to
`a signal remodulator for each of the received Satellite
`transponder Signals. As a result, this transmodulator unit
`tends to be expensive, especially when used in an MDU
`which includes fewer Satellite Signal receivers or Subscribers
`than there are channels in the transmodulator unit, i.e., in
`MDUs that will never need all of the channels provided by
`the transmodulator unit.
`SUMMARY OF THE INVENTION
`The present invention relates to a low cost System and
`50
`method for distributing a Set of program multiplexed A-V
`Signals and, possibly, existing terrestrial Signals, to a mul
`tiplicity of receiver units within one or more MDUs using an
`MDU cable network or other transmission channel. Accord
`ing to one aspect of the present invention, a receiving
`antenna receives a broadband Signal from, for example, a
`Satellite or a land-based transmitter. A transmodulator trans
`modulates Selected portions of the broadband Signal into a
`transmodulated Signal having a bandwidth that is Smaller
`than that of the received broadband Signal and transmits this
`transmodulated Signal, typically along with Standard terres
`trial signals, over a communication channel, Such as a cable
`or a wireleSS network, to a number of individual receiver
`units within an MDU. The receiver units demodulate the
`received transmodulated Signal and provide user-specified
`channels to processing or display units, e.g., video displayS,
`television Sets, audio Systems, computers, etc. The receiver
`
`4
`units also Send requests for user-Selected channels to the
`transmodulator which uses these requests to select Which of
`the portions of the broadband signal will be transmodulated.
`According to another aspect of the present invention, a
`Signal distribution System adapted to receive a composite
`Signal having a multiplicity of transponder Signals therein
`includes a transmodulator that transmodulates a Selected one
`of the transponder Signals from a first modulation Scheme to
`a Second modulation Scheme to produce a transmodulated
`Signal and a transmitter that transmits the transmodulated
`Signal over a communication channel to a plurality of
`individual receivers. A receiver receives a request Signal
`from each of the plurality of individual receivers and a
`controller Selects the Selected transponder Signal in response
`to the request Signals.
`According to another aspect of the present invention, a
`Signal distribution System for distributing a composite Signal
`having a plurality of individual program multiplex Signals
`therein over a communication channel to a number of
`individual receivers includes a main receiver that receives
`the composite Signal and a multiplicity of transmodulator
`channels coupled to the main receiver. Each of the multi
`plicity of transmodulator channels, preferably numbering
`less than the number of individual program multiplex
`Signals, transmodulates a different one of the plurality of
`individual program multiplex Signals from a first modulation
`Scheme to a Second modulation Scheme to produce one of a
`multiplicity of transmodulated Signals. A combiner com
`bines the multiplicity of transmodulated Signals at different
`carrier frequency bands to produce a combined signal and a
`transmitter transmits the combined signal Over the commu
`nication channel to the individual receivers. The Signal
`distribution System also includes a request receiver that
`receives a request Signal from each of the individual receiv
`erS and a controller coupled to the request receiver that
`controls which of the plurality of individual program mul
`tiplex Signals each of the multiplicity of transmodulator
`channels is to transmodulate.
`Moreover, the Signal distribution System generates an
`information signal, known as Side data, which may include
`channel Set-up information, frequency index set-up
`information, etc. This information Signal is used by the
`receiver to Select a requested Signal from the plurality of
`individual program multiplex Signals.
`The Signal distribution System may include a Second
`receiver adapted to receive a terrestrial Signal while the
`combiner may combine the multiplicity of transmodulated
`Signals with the terrestrial Signal to produce the combined
`Signal. Furthermore, a reception device coupled to the
`communication channel at one of the individual receivers
`may include a receiver that receives the combined signal, a
`demodulator that demodulates a portion of the received
`combined Signal and an individual transmitter that transmits
`one of the request Signals to the transmodulator indicating
`one of the plurality of program multiplex Signals to be
`transmodulated. If desired, the transmodulator channels may
`transmodulate between a quadrature phase shift keying
`(QPSK) modulation Scheme and a quadrature amplitude
`modulation (QAM) scheme, such as a 128-QAM scheme.
`According to a still further aspect of the present invention,
`a method of distributing a subset of a plurality of individual
`Signals associated with a composite Signal to multiple indi
`vidual receivers includes the Steps of receiving the compos
`ite Signal, receiving a request Signal from each of the
`individual receivers and choosing the Subset of the plurality
`of the individual signals to be distributed based on the
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`received request signals. Each of the Subset of the plurality
`of the individual Signals is transmodulated from a first
`modulation Scheme to a Second modulation Scheme and is
`transmitted over a communication channel to the individual
`receivers.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a block and partial-Schematic diagram of the
`Signal distribution System according to the present inven
`tion;
`FIG. 2 is a frequency distribution chart illustrating rep
`resentative options for transmitting received Signals along
`with existing cable and/or off-air Signals over a cable net
`work;
`FIG. 3 is a block diagram of an embodiment of the
`transmodulator of FIG. 1 according to the present invention;
`FIG. 4 is a block diagram illustrating the satellite decoder
`of the transmodulator of FIG. 3;
`FIG. 5 is a data chart illustrating the output of the data
`packetizer of FIG. 3;
`FIG. 6 is a block diagram illustrating an embodiment of
`the cable encoder of the transmodulator of FIG. 3; and
`FIG. 7 is a block diagram of an IRD associated with one
`of the receiver units of FIG. 1.
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`signal reflected from the dish antenna 14. Each of the
`channels of the LNB 16 filters either the RHCP or the LHCP
`component of the received Signal and mixes this filtered
`Signal down to an intermediate frequency band, for example,
`the portion of L-band between 950 MHz and 1450 MHz. The
`LNB 16 amplifies and provides the 500 MHz, L-band
`signals associated with each of the RHCP and LHCP com
`ponents of the downlink Signal to a transmodulator 20 via
`lines 22 and 24, respectively. Other methods for providing
`the received QPSK input signals to the transmodulator 20
`may also be used.
`The transmodulator 20 remodulates or transmodulates a
`Subset of the signals received from the LNB 16 using an
`output modulation technique that, preferably, reduces the
`bandwidth of the signals received from the LNB 16 from
`two 500 MHz bands (i.e., a total of 1000 MHz) to any lower
`bandwidth. This reduction in bandwidth may be accom
`plished by utilizing a more aggressive encoding Scheme with
`appropriate error detection and correction codes and/or by
`remodulating less than all of the received transponder Sig
`nals associated with the composite Signal. The transmodu
`lator 20 then places the transmodulated, reduced-in
`bandwidth Signal having less than all of the received
`transponder Signals on a cable plant or cable network 26
`within an MDU for distribution to a number of IRDs 30, 32,
`34, 36, 38 and 40 associated with individual receiver units
`spread throughout the MDU. The transmodulator 20 may
`instead, or in addition, distribute the transmodulated Signals
`over wire or via any wireleSS communication channel
`(including, for example, microwave and optical Systems) to
`head-ends at any other MDUs or local sites or portions
`thereof. Of course, the transmodulator 20 may also distribute
`the transmodulated signals directly to IRDS using any
`desired wireleSS communication channel.
`In order to determine which of the received satellite
`transponder Signals should be transmodulated at any par
`ticular time, the transmodulator 20 receives and decodes
`requests for particular channels or Satellite Signals from each
`of the IRDs 30-40 that are active, determines from these
`requests which of the Set of Satellite or transponder Signals
`to transmodulate and then tunes to and transmodulates only
`those Selected Satellite or transponder Signals. The trans
`modulator Sends the updated frequency indeX to the receiver
`via side data. If no transponders are available to fulfill the
`request, the transmodulator Sends an error message to the
`receiver indicating that no transponder is available.
`The transmodulator 20 may also receive Signals from a
`cable provider, a local off-air antenna 44, and/or any other
`desired Signal Source Such as those that locally generate A-V
`channels (e.g., Security camera channels, data networks, or
`informational channels) using any standard receiving
`mechanism Such as an antenna, modem or cable connection,
`and places these signals on the cable network 26 for distri
`bution to the IRDs 30-40. These other signals, referred to
`hereinafter as terrestrial signals, may comprise any cable,
`Satellite or off-air signal including, for example, Standard
`CATV, UHF, VHF, FM radio signals and/or locally gener
`ated Signals. Such as Security camera or bulletin board
`channels. The terrestrial Signals may be Summed or added
`together in a Summing network 46 (which may comprise any
`Standard signal Summer) and provided to the transmodulator
`20 via a cable line 48, or may be provided separately to the
`transmodulator 20. The transmodulator 20 may pass the
`received terrestrial Signals to the cable network 26 at the
`carrier frequencies at which the terrestrial Signals are
`received, or the transmodulator 20 may shift some or all of
`the terrestrial Signals in frequency to use the available
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`By the way of example only, the Signal distribution
`System of the present invention is described herein as
`redistributing a broadband Ku-band Satellite Signal
`(comprising up to 32, QPSK-modulated transponder signals
`transmitted from one or more Satellites at a carrier frequency
`band centered around approximately 12.45 GHz) to receiver
`units within an MDU. It is understood however, that the
`Signal distribution System of the present invention can be
`used to redistribute any other type of Satellite or land-based
`wireless signal. The term program multiplex (PM) signal is
`used herein to describe any Single or multiplex of purely
`Visual (Such as Video), purely audio, or purely data Signals
`as well as a signal comprising any combination of audio,
`Visual, data or other Signals including, for example, televi
`Sion signals, digital data Signals, etc.
`Referring now to FIG. 1, a signal distribution system 10
`according to the present invention is illustrated for use at a
`local site having one or more MDUs and/or other buildings
`therein. A local Site is considered to be any geographic area
`of relatively Small proportion Such as, for example, a
`Subdivision, a city block, etc., containing one or more
`buildings or Structures capable of having a plurality of
`individual receiving units therein. An MDU may be any type
`of multiple dwelling unit including, for example, an
`apartment, townhome, or condominium complex, a hotel/
`motel, an office building, a recreational or Sports facility, a
`cluster of Single family homes, a multi-use building and/or
`any other type of building or Structure in which multiple
`Signal receiverS may be located.
`The Signal distribution System 10 includes a main Signal
`receiver 14 disposed on, for example, the roof of an MDU
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`or any other location capable of receiving a signal transmit
`ted by a Satellite or other signal Source. The Signal receiver
`14 is preferably in the form of a 24-inch diameter parabolic
`dish antenna pointed towards, for example, Satellites that
`transmit a Ku-band or other broadband, QPSK-modulated
`PM composite signal. A two-channel LNB 16 associated
`with the dish antenna 14 receives the modulated Satellite
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`frequency spectra of the cable network 26 more efficiently.
`Where input terrestrial Signals are provided in base-band,
`suitable RF modulators may be used.
`Preferably, the transmodulator 20 transmodulates selected
`signals within the two 500 MHZ-wide QPSK-modulated
`downlink Signals into 128-QAM-modulated Signals,
`wherein each such transmodulated signal is 6 MHZ-wide.
`The transmodulator 20 may then place each of the trans
`modulated 6 MHZ-wide, 128-QAM-modulated signals on
`the cable network 26 at any unused or desired carrier
`frequency bands while, Simultaneously, Sending the terres
`trial Signals over the cable network 26 at any other desired
`carrier frequency bands. Alternatively, the transmodulator
`20 may use any other desired modulation technique to
`remodulate Selected ones of the received Satellite Signals. In
`fact, in Some cases in which only a few of the Selected
`Signals are being distributed, the transmodulator may not
`need to remodulate the Selected Signals but may, instead,
`Send these signals over the cable network 26 at the received
`modulation scheme. As noted above, the transmodulator 20
`may provide the transmodulated Signals a