United States Patent [19J
`Campbell et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,536,791
`Aug. 20, 1985
`
`[54] ADDRESSABLE CABLE TELEVISION
`CONTROL SYSTEM WITH VIDEO FORMAT
`DATA TRANSMISSION
`
`[75]
`
`Inventors: John G. Campbell, Irving; Carl F.
`Schoeneberger; Allan B. Bundens,
`both of Carrollton; Richard M. Fogle,
`Bedford; John R. Lemburg,
`Richardson, all of Tex.
`[73] Assignee: Tocom, Inc., Dallas, Tex.
`617,137
`[21] Appl. No.:
`Mar. 31, 1981
`[22] PCT Filed:
`PCT/1JS81/00414
`[86] PCTNo.:
`§ 371 Date:
`Nov. 27, 1981
`§ 102(e) Date: Nov. 27, 1981
`[87] PCT Pub. No.: W081/02961
`PCT Pub. Date: Oct. 15, 1981
`
`[63]
`
`Related U.S. Application Data
`Continuation of Ser. No. 348,937, Nov. 27, 1981, aban(cid:173)
`doned, which is a continuation-in-part of Ser. No.
`135,987, Mar. 31, 1980, abandoned.
`Int. Cl.3 ......................... H04N 7/16; H04K 1!04
`[51]
`[52] u.s. Cl ..................................... 358/122; 358/114;
`358/147; 358/259; 358/263
`[58] Field of Search ............... 358/114, 147, 263, 259,
`358/122
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`2,843,655 7/1958 Gottfried et al. .
`3,472,962 10/1969 Sanford .
`3,668,307 6/1972 Face eta!. ........................... 358/114
`3,899,633 8/1975 Sorenson eta!. .
`3,916,091 10/1975 Kirk, Jr. et al. .
`3,919,462 11/1975 Hartung eta!. ..................... 358/124
`4,068,264 1/1978 Pires .................................... 358/122
`
`4,163,254 7/1979 Block et al. ......................... 358/122
`4,225,884 9/1980 Block et al. ......................... 358/117
`4,233,628 11/1980 Ciciora ................................ 358/147
`
`OTHER PUBLICATIONS
`IEEE Transactions on Consumer electronics, vol.
`CE-25, No. 3, Jul. 1979.
`L. Solomon, Pop. Electronics, May 1979, p. 49.
`Primary Examiner-S. C. Buczinski
`Attorney, Agent, or Firm-Hubbard, Thurman, Turner
`& Tucker
`ABSTRACT
`[57]
`An addressable cable television control system controls
`television program and data signal transmission from a
`central station to a plurality of user stations. The data
`signals include both control and text signals in video
`line format which are inserted on the vertical interval of
`the television signals, thereby freeing all channels for
`transmission of both television and data signals. More(cid:173)
`over, full-channel teletext data in video line format may
`be transmitted on dedicated text channels with the mod(cid:173)
`ification of only head end processors. An intelligent
`converter at each remote user location uses the data
`signals to control access to the system on the basis of
`channel, tier of service, special event and program sub(cid:173)
`ject matter. The converter uses a graphics display gen(cid:173)
`erator to generate display signals for the presentation of
`the text data on the television receiver and for the gen(cid:173)
`eration of predetermined messages for the viewer con(cid:173)
`cerning access, emergencies and other functions. The
`converter processes vertical interval text data and se(cid:173)
`lected full-channel text data, both transmitted in video
`line format. The keyboard of the subscriber provides a
`number of different functional inputs for the subscriber
`to interface with the system. The converter also in(cid:173)
`cludes apparatus for interfacing with two-way interac(cid:173)
`tive data acquisition and control systems.
`
`8 Claims, 19 Drawing Figures
`
`VIZIO, Inc. Exhibit 1011
`1 of 32
`
`

`
`c .
`
`REMOTE
`COMPUTER
`
`/3
`
`CONTROL
`SOURCES
`TEXT
`SOURCES
`
`CENTRAL
`DATA
`CONTROL
`SYSTEM
`
`18
`
`Ill
`
`20
`
`HEAD END
`SIGNAL
`COMBINER
`
`PROGRAM
`SOURCES
`
`TELEVISION
`PROGRAM
`PROCESSOR
`
`. 22
`
`16
`
`FIG./
`
`21
`
`30
`
`32
`
`SUBSCRIBER
`INPUTS
`
`34
`
`ADDRESSABLE
`CONVERTER
`
`38
`
`USER
`TV
`
`40
`
`36
`
`VIZIO, Inc. Exhibit 1011
`2 of 32
`
`

`
`LOCAL OPERATOR
`
`SUBSCRIBER ADDRESSING
`CHANNEL CONTROL
`
`h.-42
`
`BASE BAND VIDEO
`
`r { 43
`
`I
`DEMODU-~
`I
`PROGRAM
`SOURCE ;.....__I +-~ LATOR MODULA~OR
`STANDARD HEAD
`1
`END PROCESSOR
`L-~~~~T~~~
`
`•
`
`DATA LOADED VIDEO
`
`56
`
`52
`
`I
`I 53
`I
`I
`
`f h
`
`44
`
`--------1-- ----1
`I HVP
`SATELLITE .,P_45 l? 46
`l-
`~16
`PROGRAM
`jMODULATOR
`I
`L...-....;S:.:T.:.:A;;...N:..:DA..:.tR;;.:D:.::::::.HE::::.;A~D;_--In L l l
`47
`I c....-r
`_
`END PROCESSOR
`·I-
`
`---------
`
`FROM
`OTHER
`CHANNEL
`PROCESSORS
`
`181/
`
`FSK
`DATA
`MODEM
`
`t?-2o
`
`HEAD END
`SIGNAL
`COMBINER
`
`~21
`
`CATV SIGNAL
`TO SUBSCRIBERS
`
`FIG.2
`
`VIZIO, Inc. Exhibit 1011
`3 of 32
`
`

`
`U.S. Patent Aug. 20, 1985
`
`Sheet 3 of 17
`
`4,536,791
`
`I
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`VIZIO, Inc. Exhibit 1011
`4 of 32
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`CONSOLE
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`
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`18
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`TO FSK MODULATOR
`
`CONTROL
`COMPUTER
`
`CONTROL
`TO HVP UNIT
`DATA~/
`
`.~
`
`TO REMOTE COMPUTER
`
`ADDITIONAL
`CONSOLE INPUTS
`
`68 l
`
`CARTRIDGE
`TAPE DATA
`STORAGE
`
`FLOPPY
`DISK
`SUB-SYSTEM
`!_ 70
`
`(_72
`
`L74
`
`REMOTE
`76--(__ TERMINAL
`
`PRINTER
`
`rz-78
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`
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`
`VIZIO, Inc. Exhibit 1011
`5 of 32
`
`

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`
`CONTROL CONTROL
`DATA
`DATA
`
`39
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`
`41
`
`1
`I
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`I
`I
`
`DIGITAL CONTROL
`AND TIMING
`UNIT
`
`84
`
`87
`
`80
`
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`(L..
`I
`
`BASE BA_:_:_N.;.;:D;.____..
`VIDEO-
`
`VIDEO VI
`PROCESSING
`UNIT
`
`44
`BASE BAND
`VIDEO
`SCRAMBLER t-1---'-..;;._,---+ VIDEO OUTPUT
`I
`(DATA LOADED)
`
`I
`I
`L - - - - - - - - - - -_ j
`82
`86
`
`FIG.4
`
`VIZIO, Inc. Exhibit 1011
`6 of 32
`
`

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`
`88
`r----~--------------------,
`~89
`I
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`SCRAMBLER
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`t~:
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`VIDEO
`---i.,..B-I----.1 SCRAMBLER
`SWITCHES l---+
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`
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`
`DATA LOADED
`VIDEO
`
`BASE BAND
`VIDEO )
`
`43
`
`L-------i-a--J
`
`VIZIO, Inc. Exhibit 1011
`7 of 32
`
`

`
`110
`
`RF
`SAMPLE SYNC
`
`AUDIO
`
`SCB
`
`/46
`
`114
`
`AUDIO
`
`122
`
`TONES
`SCREEN CONTROL
`DATA
`
`124
`
`DISPLAY
`MEMORY
`
`1.30
`
`/01
`
`40)
`
`FIG.6
`
`rz-/42
`
`140
`
`c .
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`
`VIZIO, Inc. Exhibit 1011
`8 of 32
`
`

`
`c .
`
`TO
`TUNER
`CONTROL
`
`109
`
`MICROPROCESSOR
`UNIT
`
`410
`
`104 \.__.
`
`412
`
`101
`
`143
`
`FROM
`I/R
`RECEIVER
`
`TO
`VIDEO
`DESCRAMBLER
`
`145
`
`FROM
`USER
`KEYBOARD
`
`414
`
`416
`
`122
`
`TIMER/
`DECODER
`
`SCB
`INTER(cid:173)
`FACE
`
`IDENTITY
`ROM
`
`TO
`AUDIO
`CONTROL
`
`124
`
`117
`
`102
`
`420
`
`TO VI
`DATA
`EXTRACTOR
`
`SCB
`
`FIG. 7
`
`TO
`TEXT /GRAPHIC
`GENERATOR
`
`VIZIO, Inc. Exhibit 1011
`9 of 32
`
`

`
`4527
`
`114 "\.
`
`456J
`
`LEVEL
`TRANSLATOR
`
`4577
`
`DATA-LOAD
`ED
`0,9
`VIDEO
`LOGIC
`COMMAND
`t/17
`
`SAMPLE AND
`HOLD CIRCUIT
`
`c~ 450
`
`4587
`
`F/G.B
`
`ANALOG
`COMPARATOR
`
`VI
`ATA
`1,5 1)
`
`L454
`
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`
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`1.0
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`
`VIZIO, Inc. Exhibit 1011
`10 of 32
`
`

`
`152 /)
`
`CATV PLANT
`
`SUBSCRIBER
`DROP
`
`SCB BUS
`AND RF
`
`TO OTHER
`,__ __ CONVERTERS
`
`34
`
`TWO-WAY
`HOME
`TERMINAL
`
`SCB
`BUS
`ADAPTOR
`
`TO OTHER
`CONVERTERS
`
`ADDRESSABLE t---~
`CONVERTER
`
`TV
`
`46
`
`REMOTE
`CONTROLI/1
`r L/40
`UNIT
`
`FIG.9
`
`FIRE
`INTRUSION
`ASSAULT
`MEDICAL
`
`56
`
`REMOTE
`CONTROL -
`UNIT
`
`{__ 140
`
`ADDRESSABLE
`CONVERTER
`
`40
`
`FIG./0
`
`TV
`
`46
`
`N
`
`~
`... o -\0
`
`00
`Ut
`
`VIZIO, Inc. Exhibit 1011
`11 of 32
`
`

`
`U.S. Patent Aug. 20, 1985
`
`Sheet 11 of 17 4,536, 791
`
`zoo/\
`
`CHANNEL CONTROL WORD
`
`SUBSCRIBER ENABLE WORD
`
`EVENT ENABLE WORD
`
`ELIGIBILITY WORD
`
`238
`
`EMERGENCY ALERT WORD
`
`EMERGENCY
`ALERT CODE
`
`TEXT TRANSMISSION WORD
`
`CHARACTER
`1
`
`CHARACTER
`2
`
`FIG. II
`
`VIZIO, Inc. Exhibit 1011
`12 of 32
`
`

`
`U.S. Patent Aug. 20, 1985
`
`Sheet 12 of 17 4,536, 791
`
`COMPARE CHANNEL
`ENABLE CODE
`TO SELECTED
`CHANNEL
`
`COMPARE TIER
`ENABLE CODE
`TO PROGRAM
`TIER CODE
`
`COMPARE EVENT
`ENABLE CODE
`TO PROGRAM
`EVENT CODE
`
`FIG. 12
`
`326
`
`DISPLAY NOT
`AUTHORIZED
`MESSAGE
`TO USER
`
`VIZIO, Inc. Exhibit 1011
`13 of 32
`
`

`
`U.S. Patent Aug. 20, 1985
`
`Sheet 13 of 17 4,536,791
`
`168
`
`171
`
`0
`
`8 p
`
`182
`
`174 ~
`OJ [I] [I]
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`0~[2]
`
`184
`
`F/G./3
`
`VIZIO, Inc. Exhibit 1011
`14 of 32
`
`

`
`U.S. Patent Aug. 20, 1985
`
`Sheet 14 of 17 4,536,791
`
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`VIZIO, Inc. Exhibit 1011
`15 of 32
`
`

`
`c .
`
`REMOTE
`COMPUTER
`
`SUBSCRIBER ADDRESSING
`CHANNEL CONTROL
`
`TO OTHER
`DATASOURCE--~----~~TT~E~XTT~F~O~R~M~A~T~T~ER~,J~I4--~--+-----------------~-t------+HVPUNITS
`DATA SOURCE --'-1
`-+---+t TEXT FORMATTER J....!..!~~~~--+--+-------------,
`DATA SOURCE
`TEXT FORMATTER
`TEXT
`'-----------------.1
`I
`39
`
`502
`
`IB
`
`FSK
`DATA
`MODEM
`
`58
`
`21
`
`CATV SIGNAL
`TO SUBSCRIBERS
`
`FROM
`OTHER
`CHANNEL
`PROCESSORS
`
`20
`
`FIG./5
`
`VIZIO, Inc. Exhibit 1011
`16 of 32
`
`

`
`~ .
`
`500
`~----L ____ l
`
`TV
`MONITOR
`2516
`
`I
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`I CRT AND
`I KEYBOARD
`L__f- _ _;_ _____ ,
`
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`
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`COMPUTER
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`
`VIZIO, Inc. Exhibit 1011
`17 of 32
`
`

`
`U.S. Patent Aug. 20, 1985
`
`Sheet 17 of17 4,536,791
`
`COMPARE CHANNEL
`ENABLE CODE
`TO SELECTED
`CHANNEL
`
`COMPARE TIER
`ENABLE CODE
`TO PROGRAM
`TIER CODE
`
`COMPARE EVENT
`ENABLE CODE
`TO PROGRAM
`EVENT CODE
`
`FIG. 17
`
`326
`
`DISPLAY NOT
`AUTHORIZED
`MESSAGE
`TO USER
`
`VIZIO, Inc. Exhibit 1011
`18 of 32
`
`

`
`1
`
`4,536,791
`
`ADDRESSABLE CABLE TELEVISION CONTROL
`SYSTEM WITH VIDEO FORMAT DATA
`TRANSMISSION
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`This application is a continuation of application Ser.
`No. 348,937, filed Nov. 27, 1981, now abandoned,
`which is a continuation-in-part application of U.S. ap(cid:173)
`plication Ser. No. 135,987, filed Mar. 31, 1980, now
`abandoned.
`
`BACKGROUND OF THE INVENTION
`This invention relates to an addressable cable televi- 15
`sion control system. More particularly, the present in(cid:173)
`vention relates to a cable television system having a
`multiple-function addressable converter and including
`data transmission in video format during the vertical
`interval of the video field or during substantially the 20
`entire video field.
`In recent years, the availability of cable television
`programs and services for the general public has ex(cid:173)
`panded rapidly. Communication satellites have enabled
`nationwide programming for a number of "super sta- 25
`tions". Sophisticated two-way interactive cable com(cid:173)
`munication systems have laid the groundwork for a
`wide spectrum of cable television and data communica(cid:173)
`tion services for the consuming public. After years of
`development, cable television systems have been or are 30
`now being installed in many major cities to provide the
`television consumer with a vast array of programming
`choices as well as many other services which can be
`utilized at home, such as shopping, banking and school(cid:173)
`ing. Other services provided by such systems include 35
`home security monitoring, medical and emergency alert
`signaling and information retrieval.
`In order to provide these new services and programs
`in a systematic and efficient manner, generalized con(cid:173)
`trol systems are required which can supervise access to 40
`both one-way and two-way sophisticated cable commu(cid:173)
`nication systems having different degrees of complex(cid:173)
`ity. Control is required to differentiate and limit access
`on several bases, including different levels or tiers of
`subscribers to different television channels, and differ- 45
`ent programs and events on a given channel. In addi(cid:173)
`tion, for many subscribers it is desirable to be able to
`limit access to certain programs because of the program
`subject matter. Presently, there are no cable systems
`having this degree of sophistication in controlling pro- 50
`gram access. Even simpler conventional cable systems
`which provide for limiting program access must be
`two-way interactive systems requiring more complex
`and expensive equipment than one-way systems.
`Besides this problem of coordinating cable communi- 55
`cations, the need for efficiency in the transmission of
`data has become increasingly apparent. Although ap(cid:173)
`proximately 55 video and sound channels are presently
`available between the allocated television frequencies of
`50 and 400 megahertz, the varied types of possible cable 60
`television programming and data transmission services
`require the efficient utilization of these frequencies. For
`example, cable television programming includes mov(cid:173)
`ies, special events, news, consumer programming, com(cid:173)
`munity access and religious programming. An almost 65
`limitless range of data can be provided, including re(cid:173)
`ports on stock and money markets, weather reports,
`airline schedules, shopping directories, entertainment
`
`2
`schedules, traffic reports, home security data emer(cid:173)
`gency and first aid information and unlimited library
`textual information. The possibility for cable system
`operators to lease available cable channels to private
`concerns for these and other services makes it impera(cid:173)
`tive that cable transmission control be efficient and
`flexible. In order to effectively utilize the available
`portion of the electromagnetic spectrum for such a wide
`variety of programming and data transmission, the
`10 cable system should be able to process the data quickly
`and efficiently while using relatively simple and inex(cid:173)
`pensive equipment which is affordable to the general
`consuming public.
`In the last few years, various experiments have been
`conducted regarding the transmission of data over the
`vertical blanking interval of a normal television signal.
`This interval in the video signal occurs 60 times each
`second as the cathode ray tube beam sweeps from the
`buttom to the top of the TV screen and is relatively
`unused for the transmission of data. Some early systems
`such as that shown in U.S. Pat. No. 3,769,579 issued
`Oct. 30, 1973, utilized the vertical interval for transmit(cid:173)
`ting control signals to individual transponders at the
`subscriber locations. More recently, there has been
`experimentation with television broadcasting systems
`which transmit visual data on the vertical blanking
`interval, referred to as teletext transmission, for display
`as pages of text on suitably equipped television receiv-
`ers. These experimental systems have generally been
`limited to over-the-air broadcasting of teletext transmis(cid:173)
`sions for a single channel, and the necessary apparatus
`for cable television systems has been regarded as too
`complicated and expensive to be practical when com-
`pared to the high-speed transmission of compact data
`over a dedicated channel.
`It is desirable in many instances to dedicate an entire
`television channel to the transmission of data rather
`than video signals. Prior art systems for dedicated data
`channels typically require special transmitters and re(cid:173)
`ceivers different from those used for the transmission of
`video signals in order to achieve the desired high baud
`(bits per second) rate to efficiently utilize the channel
`bandwidth. This special data transmission equipment
`has resulted in substantial cost and complexity, particu(cid:173)
`larly at each remote user terminal where a different
`receiver is usually required for each dedicated data
`channel. A simple and inexpensive system for the high
`speed transmission of data on a dedicated data channel
`has been greatly needed.
`
`SUMMARY OF THE INVENTION
`The present invention provides a relatively inexpen(cid:173)
`sive and simple cable television system having the capa(cid:173)
`bility of controlling access to a wide range of television
`program and data signals while efficiently transmitting
`data signals in a video format during the vertical inter(cid:173)
`val (VI) of each television program channel. This VI
`data not only provides control data for an intelligent
`converter unit, but also provides a substantial amount of
`textual data per channel for use either to provide addi(cid:173)
`tional data to supplement a channel television program
`or as a separate all textual and graphic channel.
`The present invention includes an intelligent address(cid:173)
`able converter designed to convert and descramble
`video for up to 55 CATV channels. For dual cable
`systems, an optional cable switch on the converter dou(cid:173)
`bles the available number to 110 channels. The con-
`
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`FIGS. 9 and 10 are schematic diagrams showing two
`preferred methods of connecting the converter of FIG.
`6 in a CATV system;
`FIG. 11 is a schematic diagram showing the data
`format for the system of the present invention;
`FIG. 12 is a flow diagram showing the operation of
`the converter shown in FIG. 6;
`FIG. 13 is a top plan view of the keyboard of the
`converter of FIG. 6;
`FIG. 14 is a diagram showing a video layout for
`full-channel teletext data transmission in accordance
`with another embodiment of the present invention;
`FIG. 15 is a block diagram for the preferred embodi(cid:173)
`ment of FIG. 14 of the head end portion of the system
`shown in FIG. 1;
`FIG. 16 is a block diagram of the screen composition
`system and selective data retrieval system shown in
`FIG. 15; and
`FIG. 17 is a flow diagram showing the operation of
`the converter shown in FIG. 16 operating in conjunc(cid:173)
`tion with the head end of FIG. 15.
`
`3
`verter of the present invention receives control data
`which allows the system operator to control subscrip(cid:173)
`tion television services on a per channel, per service
`tier, and per event basis. In addition, the system and
`converter of the present invention enables each sub(cid:173)
`scriber to define his own level of required eligibility
`based on program subject matter.
`The system of the present invention also enables a
`complementary text channel to be transmitted on the
`vertical interval of each of the incoming video signals 10
`and to be decoded and displayed as an alternate channel
`to the video programming. The data for the comple(cid:173)
`mentary text channel is preferably displayed in a combi(cid:173)
`nation of text and graphics. This capability effectively
`adds 55 additional text channels for a wide spectrum of 15
`data-type information for the consumer. Thus, the pres(cid:173)
`ent system provides 110 independent channels of televi(cid:173)
`sion program and text viewing in a one cable system and
`220 channels in two cable systems. Moreover the con(cid:173)
`trol system of the present invention, when used in con- 20
`junction with appropriate two-way interactive appara(cid:173)
`tus, provides a complete two-way interactive communi(cid:173)
`cation system including pay-per-view, home security,
`opinion polling, channel monitoring, information re(cid:173)
`trieval, and with additional equipment, energy manage- 25
`ment.
`Moreover, the present invention provides a relatively
`inexpensive and simple cable communication system
`having the capability of transmitting data signals in a
`video format over substantially the entire video field of 30
`selected television program channels. By transmitting
`data in die video format over these dedicated data chan(cid:173)
`nels, the present invention minimizes the need for spe(cid:173)
`cial additional expensive equipment, particularly special
`data receiver equipment for each converter unit. 35
`Rather, each addressable converter of the present in(cid:173)
`vention is readily adapted to receiving selected lines of
`data transmitted in video format without requiring addi(cid:173)
`tional expensive receiver equipment.
`For a better understanding of the present invention, 40
`together with other and further objects and features
`thereof, reference is made to the following description
`taken in connection with the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a simplified block diagram of a preferred
`embodiment of the addressable cable television control
`system of the present invention;
`FIG. 2 is a block diagram of a preferred embodiment
`of the head end portion of the system shown in FIG. 1;
`FIG. 2A is a diagram showing the line layout of a
`video field according to the present invention;
`FIG. 2B is a time-based diagram showing the video
`line format of data transmission in accordance with the
`present invention;
`FIG. 3 is a block diagram of the programming con(cid:173)
`trol system shown in FIG. 2;
`FIG. 4 is a block diagram of the head end video
`processor shown in FIG. 2;
`FIG. 5 is a more detailed block diagram of the head
`end video processor of FIG. 4;
`FIG. 6 is a block diagram of a preferred embodiment
`of the addressable converter of the present invention
`shown in FIG. 1;
`FIG. 7 is a block diagram of the converter control
`logic shown in FIG. 6;
`FIG. 8 is a block diagram of the VI data extractor
`unit shown in FIG. 6;
`
`DETAILED DESCRIPTION
`FIG. 1 shows a simplified block diagram of a one(cid:173)
`way cable television system 10 in accordance with the
`present invention. A head end station 11 includes a
`central data system 12 utilizing a control computer
`which gathers data from a wide variety of sources and
`formats the data for transmission on video frequency
`channels. The central data control system preferably
`has a two-way interface link 13 with a remote computer
`which may be used for central control and billing func(cid:173)
`tions. The formatted data is then transmitted by com(cid:173)
`munications link 14 to a television program processor
`16 where it is incorporated into the vertical blanking
`intervals of video signals generated by a variety of tele-
`vision program sources. In addition, the data may be
`formatted for transmission in a separate channel dedi(cid:173)
`cated only for the transmission of data. The dedicated
`data channel transmissions are connected over link 18 to
`a head end signal combiner 20 where they are combined
`with a plurality of video signals transmitted from televi(cid:173)
`sion program systems 16 along transmission link 22. The
`head end unit then transmits the combined cable televi-
`45 sion and data signal to remote subscribers. Normally,
`the signals are then transmitted through a cable net(cid:173)
`work, referred to as a cable plant to a plurality of sub(cid:173)
`scribers.
`FIG. 1 shows a single cable plant 30 servicing a plu-
`50 rality of cable television subscribers by way of a one(cid:173)
`way data link 32. The transmitted signals are received
`by an addressable converter 40 on a one-way data bus
`32. Converter 40 then processes the data on line 38 as
`determined by subscriber input 34 for desired viewing
`55 on one or more television sets 36.
`Referring now to FIG. 2, one preferred embodiment
`of the data control system 12 and television program
`processor 16 is shown in greater detail. This preferred
`embodiment which is shown in FIGS. 2 through 12
`60 concerns a system which transmits data in the vertical
`interval of each video field. Another preferred embodi(cid:173)
`ment disclosing a full-channel data transmission system
`using a video format will be discussed thereafter.
`As shown in FIG. 2, a programming control system
`65 (PCS) 50 generates a continuous stream of data that
`contains a mixture of subscriber addressing signals and
`channel control signals. This data is transmitted to a
`plurality of head end video processors (HVP) 52 and 53
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`for combining with video signals in a plurality of differ(cid:173)
`ent channel frequencies. PCS 50 is also preferably con(cid:173)
`nected by a two-way data link to a remote computer for
`use in various control functions.
`A text formatter system 54 receives data from a wide
`variety of sources such as weather, news, stock and
`others which are formatted for video transmission and
`then selectively transmitted in text form to the plurality
`of HVP units 52, 53. The text formatter system 54 pref(cid:173)
`erably is comprised of a plurality of text formatters, 10
`each processing data from a text or graphics source. A
`variety of manufacturers produce equipment for cable
`television digital channels which are easily adaptable to
`the present system. One source of suitable conventional
`formatters is Video Data Systems, Happaque, L.I., N.Y. 15
`Video signals are generated for input to each HVP
`unit by conventional sources, either from local video
`input sources as shown for HVP unit 52 or satellite
`video input sources for HVP unit 53. In either case, the
`signals are processed by a conventional channel proces- 20
`sor 56 having modulator and demodulator units and a
`standard head end processor. Each television channel is
`preferably processed at base band video for purposes to
`be explained later.
`The subscriber addressing and channel control data 25
`from PCS 50 is input to HVP 52 on line 41 where it is
`inserted in the vertical interval of the video signal. The
`channel control data from PCS 50 is processed at HVP
`52 to generate scrambler signals, program identification
`signals, tier signals and eligibility code signals as will be 30
`discussed later. These signals are utilized by each sub(cid:173)
`scriber's addressable converter 40 to determine the
`particular subscriber's authorization to receive each
`program and to control descrambling of the video sig(cid:173)
`nals.
`One of the text signals from text formatter 54 is also
`input to HVP 52 on line 39 to be inserted into the verti-
`cal interval of the video signal. Preferably, a different
`type of textual data are inserted into the vertical interval
`of each video channel so that a complementary text 40
`channel may be selected by each remote subscriber.
`HVP unit 52 then routes the base band-video output
`with vertical interval data on line 44 to a standard head
`end modulator and processor in processing unit 56.
`From there, the signal is sent to master head end unit 20 45
`where it is combined with signals from other channel
`processors to provide the total multiple channel CATV
`signal for output on line 21 to the cable plant. An FSK
`data modulator 58 is connected directly between PCS
`50 and head end signal combiner 20 by line 18 for trans- 50
`mission of data on dedicated data channels.
`In order to understand how a data signal is transmit(cid:173)
`ted on the vertical interval of a television program sig(cid:173)
`nal, the vertical interval of a conventional television
`signal will be described. Referring to FIG. 2A, each 55
`television signal is made up of a series of "lines" each of
`which represent the length of time required for the
`cathode ray tube of the television set to make one hori(cid:173)
`zontal sweep across the screen. The number of horizon(cid:173)
`tallines required to cover the screen is called a field 700, 60
`and there are two interlocking fields, both having 262.5
`lines which together form a frame. In conventional
`systems, 30 frames are transmitted each second to make
`up the television picture. Each time the cathode ray
`tube reaches the bottom of the screen it must sweep 65
`diagonally upward to the top of the screen to begin a
`new field. This time period 702 is referred to as the
`"vertical blanking interval" or simply "vertical inter-
`
`6
`val" and is normally approximately 21 lines in length.
`The television picture 704 begins at about line 21 and
`extends to about line 261, but normally the picture is
`viewable on most television sets only between about
`lines 25 and 255.
`Although no television picture data is transmitted
`during the vertical interval, the television industry has
`provided for a number of different types of control
`transmission on certain lines of the interval. In most
`cases, the first nine lines of the vertical interval are used
`for equalizing and for vertical synchronization. Lines 10
`to 14 are normally at black level to minimize picture
`interference on some sets. Thus, only lines 15 to 21 are
`available for data transmission. Lines 15 and 16 have
`already been utilized at least experimentally for other
`purposes. Lines 19-21 are normally used for network
`control information for transmission to the receiver sets.
`Thus, lines 17 and 18 are the only ones which are
`presently available for vertical interval data transmis(cid:173)
`sion 710 using the invention of the present system.
`These two lines normally contain network testing data
`to determine proper reception by the head end system.
`Once the television signals have been received, lines 17
`and 18 can be cleared for passing data to the converters
`using the present invention. It should be understood
`that if additional lines in the vertical interval are cleared
`in the future, they could also be used for data transmis(cid:173)
`sion in accordance with the present invention.
`Preferably, the present invention uses lines 17 and 18
`of the vertical interval to transmit both the text data and
`the subscriber address and channel control data. In one
`field of a given frame lines 17 and 18 are used to trans(cid:173)
`mit text data, and in the other frame field, the subscriber
`address and channel control data is projected on lines 17
`35 and 18. The present invention also uses line 10 which is
`at the black "zero" voltage level of each vertical inter(cid:173)
`val for a DC reference level 712 for the data signals.
`This reference signal passes to the converter as part of
`the vertical interval where it is used as a reference level
`for data extraction. This procedure greatly enhances the
`accuracy of the data transmission by automatically
`compensating for any DC level shift in the vertical
`interval portion of the television signal.
`Using the procedure described above an effective text
`character transfer rate of about 240 characters per sec(cid:173)
`ond is achieved. This is a relatively slow rate compared
`to some other methods of data transmission. However,
`since the text may be transmitted over all 55 television
`program channels the total text available to the user is
`very substantial. Moreover, as previously mentioned,
`the present invention may include one or more dedi-
`cated channels for only text data transmission using the
`"line" or video format which will be described more
`fully in FIGS. 2B and 11. By using most of the 525 lines
`of each television signal frame for text data transmission
`a vast quantity of text can be transmitted and received
`on a given channel using the transmitting and receiving
`apparatus of the present system. No special expensive
`data transmission or receiving equipment is required.
`A better understanding of the line or video format of
`the data used in the present invention may be obtained
`by reference to FIG. 2B, which shows a standard timing
`diagram for a single television line of the type shown in
`FIG. 2A. This is a standard video line format in accor(cid:173)
`dance with FCC or NTSC requirements. The amplitude
`of the video signal is measured in standard IRE units.
`As shown in the figure, the video signal begins with
`a negative horizontal sync pulse 720 of about 40 IRE
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`units. This pulse establishes the beginning point of the
`horizontal sweep of the cathode ray tube across the
`screen. Next, a color burst oscillating pulse 722 occurs
`which is normally used to synchronize color decoding
`circuitry in a television receiver.
`Data is encoded in the video scan line 724 following
`the color burst signal 722 as shown in FIG. 2B. This line
`is normally composed of 92 bit intervals with each bit
`being identified as "1" with an amplitude level of 50 to
`80 IRE units or "0", carrying an amplitude of approxi(cid:173)