"ljnited fitatea Patent
`
`[19]
`
`[11]
`
`4,225,884-
`
`Block et al.
`[45] Sep. 30., 11980
`
`
`
`[57]
`
`ABSTRACT
`
`A subscription television system and method in which
`billing information regarding programs actually viewed
`by a subscriber of the system is accumulated over non-
`dedicated telephone lines. A scrambled television pro-
`gram signal containing a block of television program
`material, a program identification code unique to the
`block of program material, and a program category
`code, is broadcast. The codes are preferably included in
`the vertical retrace interval of the video portion of the
`program signal and the transmitted program signal is
`selectively received at a subscriber station and selec-
`tively unscrarnbled to permit viewing of the block of
`program material being transmitted in response to sub-
`scriber action indicating acceptance for viewing of the
`block of program material. The received program cate-
`gory code is compared with a locally generated cate-
`gory code to determine whether the program is accept-
`able for viewing. The program identification code is
`detected and stored for subsequent transmission in re-
`sponse to the subscriber action indicating acceptance
`for viewing of the received block of program material.
`The program identification code stored at
`the sub-
`scriber station is selectively accessed from a remote
`location over telephone lines on other than a real time
`basis (e.g., a periodic basis) to thereby provide billing
`information at the remote location as to programs actu-
`ally viewed by the subscriber. The subscriber can thus
`be billed monthly or on some desired periodic basis for
`programs actually viewed during the preceding period.
`The billing period can be varied from the remote loca-
`tion to provide a means to control the number of pro-
`grams which a subscriber can receive.
`
`14 Claims, 6 Drawing Figures
`
`[54] METHOD AND SYSTEM FOR
`SUESCRIPTXON TELEVISION BILLING
`AND ACCESS
`
`[75]
`
`Inventors:
`
`Robert S. Block, Marina Del Ray,
`Califi; John R. Martin, Milwaukee,
`Wis.
`
`Telease, Inc., Beverly Hills, Calif.
`1:73] Assignee:
`[21] Appl. No.: 920,846
`
`:22] Filed:
`
`Jun. 30, 1978
`
`Reiated 1.1.8. Application Data
`
`[63]
`
`Continuation-in-part of Ser. No. 768,404, Feb. 14, 1977,
`Pat. No. 4,163,254.
`
`{S1}
`[52]
`
`Int. Cl? ............................................. .. H04N 7/16
`‘US. Ci. .................................... .. 358/122; 358/84;
`358/117; 358/124
`{S8} Field of Search ............... .. 358/84, 114, 122, 123,
`358/124, 117
`
`{S6}
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`........................ .. 358/84
`Callais et al.
`2/1974
`11/1975 Hartung et al.
`. 358/117
`5/1977 Nieson . . .. . . .
`. . . .. 358/117
`5/1977
`Loshin
`. 358/124
`8/1977
`Porter
`.. 358/84
`l/1978
`Pires ..... ..
`. 358/122
`5/1978 Nieson
`. 358/124
`9/1978
`Pires ..... ..
`. 358/124
`12/1978
`Chomet .............................. .. 358/122
`
`
`
`3,790,700
`3,919,462
`4,024,574
`4,025,948
`4,04-4,376
`4,068,264
`4,091,417
`4,115,807
`4,130,833
`
`Primary Exam1'ner——S. C. Buczinski
`Attorney, Agent, or F1'rm——Burns, Doane, Swecker &
`Mathis
`
`FROG
`
`MODULATORS
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`
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`5
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`
`PROGRAM
`ID CODE
`_ SELECTOR
`
`Amazon Ex. 1008
`
`IPR Petition - USP 7,801,304
`
`Page 1
`
`

`
`U.S. Patent
`
`Sep. 30, 1980
`
`Sheet 1 of4
`
`4,225,884
`
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`

`
`U.S. Patent
`
`Sep. 30, 1980
`
`Sheet 2 of 4
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`4,225,884
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`Page 3
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`

`
`U.S. Patent
`
`Sep.30,198O
`
`Sheet 3 of4
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`4,225,884
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`Page 4
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`

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`U.S. Patent
`
`Sep. 30, 1980
`
`Sheet4 of4
`
`4,225,884
`
`CODE
`
`DETECTOR
`
`FIG 5
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`"'
`
`SVID
`
`
`'
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`CODE
`GENERATOR
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`
`Page 5
`
`

`
`1
`
`4,225,884
`
`METHOD AND SYSTEM FOR SUBSCRIPTION
`TELEVISION BILLING AND ACCESS
`
`RELATED APPLICATIONS
`
`This application is a continuation-in-part of copend-
`ing United States patent application Ser. No. 768,404
`filed Feb. 14, 1977, now issued as U.S. Pat. No.
`4,163,254 on July 31, 1979.
`BACKGROUND OF THE INVENTION
`
`The present invention relates to subscription televi-
`sion and more particularly to a method and system for
`obtaining billing information regarding programs
`viewed by a subscriber of a subscription television sys-
`tern.
`
`Since the advent of subscription or pay television,
`numerous techniques have been devised to bill the sub-
`scribers for the service provided. It has been suggested
`that the subscriber pay for subscription television ser-
`vices on a fixed charge basis, a uniform cost per unit use
`basis, or on a per program charge basis. More recent
`systems have adopted the per program basis for billing.
`It will be appreciated that a fixed charge or uniform
`charge per unit basis of billing presents the least prob-
`lems with regard to recording and calculating billing
`charges. With a fixed charge system as is used with most
`cable television or CATV systems, the station operator
`merely bills the subscriber a fixed amount on a monthly
`basis.
`The uniform per unit use billing involves somewhat
`more complex procedures since actual viewing time
`must be recorded and somehow made available to the
`operator for billing purposes. Moreover, the viewing
`time must be registered in conjunction with the identity
`of each subscriber so that an individual subscriber can
`be billed for his viewing time.
`.
`The most complex billing system and yet the most
`desirable from the standpoint of the subscriber is billing
`on the basis of actual programs viewed with different
`charges for different programs. In such a system, the
`billing entity must know both the identity of the sub-
`scriber and the identity of the programs viewed during
`a billing period.
`‘ Several billing systems have been developed in order
`to charge subscribers to a pay television system on the
`basis of programs actually viewed. Typical of these
`types of systems are the coinbox systems that are exem-
`plified by U.S. Pat. No. 3,021,383. In such a system, the
`subscriber must deposit a certain amount of money in a
`coinbox attached to the receiver in order to view a
`particular program. Different programs may be as-
`signed different charges so that, for example, a particu-
`lar movie may cost less to view than a sporting event.
`With such a system, payment for the program enables
`the viewing of a program and payment is thus assured.
`However, the billing entity (the system operator) must
`collect the money from the coinboxes on a periodic
`basis, requiring considerable manpower and also requir-
`ing access to the subscriber’s home.
`Another approach to billing on a per program basis
`requires the subscriber to place a telephone call to some
`central location and request the receipt of a particular
`program. The calling subscriber’s equipment is then
`enabled and charges for the program can be recorded
`and billed to the calling subscriber. It will be appreci-
`ated that such a system may encounter difficulties in
`large service areas with a large, number of subscribers.
`
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`In addition, the subscriber’s telephone must be utilized
`frequently for this purpose.
`Other approaches to the billing problem in pay TV
`systems include the one of cards or paper tapes that are
`used at the subscriber location to record viewing infor-
`mation. In a particular system, a card is mailed to the
`subscriber and is required for operation of the subscrib-
`er’s receiver. The card is punched or otherwise im-
`printed at the subscriber location to record program
`charges and must be mailed or otherwise transmitted to
`the system operator so that charges may be assessed.
`Typical of these types of systems are those shown in
`U.S. Pat. Nos. 3,470,309, 3,475,547 and 3,531,583.
`Another type of billing system may be characterized
`as a real time metering or interrogating system such as
`that shown in US. Pat. Nos. 3,396,232, 3,716,654 and
`3,733,430. These systems typically interrogate the re-
`ceivers or otherwise monitor the status of the receivers
`on a program by program basis (e.g., through use of
`special transducers) to determine if the subscriber is
`watching a particular program. This information can be
`used for billing purposes as well as audience survey
`purposes and the like.
`It can be seen that the foregoing systems suffer from
`numerous deficiencies including system complexity,
`enormous time consumption, reliance on subscriber
`action to receive billing information, and the like. It is
`accordingly an object of the present invention to obvi-
`ate the foregoing and other deficiencies of the prior art
`pay television system billing procedures through the use
`of a novel method and system for billing on a per pro-
`gram basis with a minimum of complex equipment and
`a minimum of human intervention.
`It is another object of the present invention to pro-
`vide a novel method and system for obtaining billing
`information regarding programs actually viewed by a
`subscriber of a pay television system wherein program
`identification data is recorded and is accessed on a peri-
`odic basis from a central location, thus, eliminating the
`need for the gathering of the information through the
`intervention of the system subscriber.
`It is yet another object of the present invention to
`provide a novel method and system for obtaining billing
`information regarding programs actually viewed by a
`pay television system subscriber which utilizes a mini-
`mum of complex equipment and makes use of existing
`equipment at the subscriber location including a tele-
`phone at the location.
`It is a further object of the present invention to pro-
`vide a novel subscriber television system and method in
`which scramble and program codes are received in the
`program video signal and are used in conjunction with
`a telephone access unit to unscramble the received pro-
`gram signal and record program viewing under the
`control of a central station linked to the access unit over
`non-dedicated telephone lines.
`It is another object of the present invention to pro-
`vide a novel subscriber television system and method in
`which the subscriber has the capability to select a pro-
`gram for viewing from among a number of different
`available programs and selectively prevent the viewing
`of others of the available programs.
`It is yet a further object of the present invention to
`provide a novel
`subscriber
`television system and
`method in which the length of the billing period can be
`varied to provide flexibility in the control of programs
`available to the subscriber.
`
`Page 6
`
`

`
`3
`These and other objects and advantages of the pres-
`ent invention will become apparent to one skilled in the
`art to which the invention pertains from the following
`detailed description when read in conjunction with the
`appended drawings.
`
`4,225,884
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a functional block diagram illustrating a
`subscription or pay television system in accordance
`with the present invention;
`FIG. 2 is a signal diagram illustrating an exemplary
`form of the video portion of the program signal with
`scramble and program ID codes as utilized in the sys-
`tem of FIG. 1;
`FIG. 3 is a functional block diagram illustrating the
`central transmitting station of FIG. 1 in greater detail;
`FIG. 4 is a functional block diagram illustrating the
`subscriber station equipment of FIG. 1 in greater detail;
`FIG. 5 is a functional block diagram illustrating an
`access unit with a settable clock for providing variable
`length billing periods; and
`FIG. 6 is a block diagram illustrating a category
`selection device which can be included with the sub-
`scriber station equipment.
`-
`DETAILED DESCRIPTION
`
`Referring now to FIG. 1, the system according to the
`present invention generally comprises central station
`equipment 10 which supplies program signals in a
`scrambled form to subscriber station equipment 12 at
`each of the subscriber stations. As will be described
`hereinafter in greater detail,
`the scrambled program
`signal includes scrambled audio and video signals as
`well as various synchronizing signals arid codes. The
`scrambled program signal SPROG is supplied to the
`subscribers either by conventional broadcast or cable
`techniques.
`The audio and video signals from a conventional
`source such as television camera equipment are applied
`to a program signal scrambler 14 to produce respective
`scrambled audio and video signals SAUD and SVID. In
`addition, the program signal scrambler 14 provides a
`transmitted scramble code TSC for transmission with
`the scrambled program audio and video signals. The
`SAUD, SVID and TSC signals from the scrambler 14
`are provided to a suitable conventional transmitter 16
`for production of a scrambled program signal that in-
`cludes the code signals and for transmission to sub-
`scriber stations.
`A program ID code unit 18 synchronized with the
`scrambled video signal and scramble code provides a
`program code TPC for transmission with the program
`signals. This program ID code TPC is combined with
`the scrambled program video and the scrambled code
`for transmission to the subscriber as is described herein-
`after in greater detail. In addition, the central station
`equipment 10 may include a billing data gathering com-
`puter 20. It should however be understood that the
`billing data gathering computer 20 may be located at
`any convenient central location and need not be located
`at the transmitting site.
`The scrambled program signal SPROG from the
`"central station equipment 10 is received by a program
`signal receiver 22 at the subscriber station and the re-
`ceived signal is supplied both to a program signal un-
`scrambler 24 and to a control and storage unit 26. The
`program signal unscrambler 24 operates in response to
`control signals from the control and storage unit 26 to
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`unscramble the incoming program signal and provide
`unscrambled audioand video signals UAUD and UVID
`to a conventional modulator 28. The modulator 28
`modulates a carrier signal of an appropriate carrier
`frequency with the unscrambled audio and video signals
`and supplies the unscrambled program signal
`in the
`form of a modulated carrier wave to the television an-
`tenna terminals for use by the subscriber's television set
`in a conventional manner.
`A subscriber control unit 30 provides subscriber con-
`trol of program viewing. The subscriber control unit'30
`may, for example, include one or more subscriber ma-
`nipulated controls which permit the subscriber to selec-
`tively tune a conventional tuner in the program signal
`receiver 22 in order to select a desired program as well
`as to provide appropriate signals.to the control and
`storage unit 26 indicating that the subscriber has se-
`lected a program for viewing and has thus assumed the
`obligation to pay that program.
`The control and storage unit 26 detects code signals
`in the incoming scrambled program signal for unscram-
`bling and billing purposes. In this respect, the transmit-
`ted scrambled code TSC is detected by the control and
`storage unit 26 and compared to a received scramble
`code RSC supplied to the control and storage unit
`through an access unit 32 and stored in the control and
`storage unit. The control and storage unit 26 also de-
`tects the transmitted program code TPC in the incom-
`ing program signal and stores the program code of a
`particular program being viewed. The stored program
`code SPC is then supplied on command to the access
`unit 32. As illustrated, the access unit 32 is connected to
`telephone lines which are in turn connectable through
`conventional
`telephone switching equipment
`to the
`telephone lines leading to the billing data gathering
`computer 20.
`In operation, the audio and video program signals are
`supplied to the program signal scrambler 14 and are
`scrambled in any suitable conventional manner. For
`example, these signals may be scrambled in accordance
`with the techniques described in U.S. Pat. No. 3,824,332
`through selective inversion of portions of the video
`signal. The scramble code TSC may be inserted into the
`video signal
`in order to permit unscrambling of the
`program signals at the subscriber station as is set forth in
`U.S. Pat. No. 3,824,332.
`In addition, each program that is transmitted in a
`scrambled form may be identified by placing a program
`code TPC in the video signal during the vertical retrace
`interval of the signal or at any other convenient loca-
`tion. In this connection, the program code and scramble
`code may be combined with the program video at the
`appropriate locations by synchronizing the generation
`of these codes with the video synchronizing signals in
`any known manner such as that shown in the referenced
`U.S. Pat. No. 3,824,332.
`transmitter 16 combines the
`The program signal
`video and code signals and transmits this combined
`signal together with the audio signal at an appropriate
`carrier frequency. The resultant video portion of the
`program signal may thus take the form illustrated in
`FIG. 2. For example, as is illustrated in FIG. 2, the
`successive horizontal lines of the video signal are con-
`ventionally separated by horizontal synchronization
`pulses and each frame of video signals is separated by a
`vertical retrace interval or vertical synchronization
`signal. During" the vertical retrace interval, various
`equalizing and synchronization pulses are provided and
`
`Page 7
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`

`
`5
`it is in this interval that the scrambled and program ID
`_codes are preferablycombined with the transmitted
`program signal. These codes are preferably encoded in
`a digital form as illustrated in FIG. 2 although it should
`be understood that any well known coding technique
`such as the tone burst technique described in U.S. Pat.
`No. 3,824,332 may be utilized.
`_
`With continued reference to FIGS. 1 and 2, the trans-
`mitted program video signal is thus in the form of a
`scrambled signal (e.g., with selected frames of video
`information inverted) with codes inserted at appropri-
`ate locations to identify the program being transmitted
`and to indicate to the subscriber equipment the state of
`the subsequent video signal‘ (i.e.,
`inverted or non-
`inverted). The program signal receiver 22 selects a
`particular carrier frequency through the use of a con-
`ventional tuner and demodulates the incoming program
`signal to recover the audio, video and code signals.
`The recovered scrambled program signal is supplied
`to the program signal unscrambler 24 and to the control
`and storage unit 26 for unscrambling and detection of
`the codes contained in the video portion of the program
`signal. The scramble codes detected in the program
`signal are used to generate the control signals that con-
`trol the unscrambling of the program signal by the un-
`scrambler 24. The program code in the incoming video
`signal is stored in a storage unit that may be selectively
`accessed by an access unit 32. The access unit 32 may
`be, for example, of the type disclosed in copending U.S.
`patent applications Ser. No. 683,161 filed May 4, 1976
`and Ser. No. 701,033 filed June 29, 1976, both by Robert
`S. Block and John R. Martin.
`
`It will be appreciated that the invention provides a
`relatively simple manner of subscriber billing that al-
`lows for the identification of programs actually viewed
`and the rapid gathering of this information on a periodic
`basis long after a program has been viewed. Each sub-
`scriber station is selectively accessed so that program
`viewing information in association with subscriber iden-
`tification information is available at a central location
`for billing purposes. Moreover,
`the billing gathering
`computer 20 has complete control over the subscriber
`station equipment 12 in the sense that it can deny new
`scrambled codes to the subscriber station equipment on
`a selective basis if that particular subscriber has not paid
`his bill or for other relevant reasons.
`To facilitate an understanding of the present inven-
`tion, the central station equipment 10 and the subscriber
`equipment 12 are illustrated in greater detail in FIGS. 3
`and 4, respectively.
`Referring to FIG. 3, the central station equipment
`receives the unscrambled program signal UPROG in-
`cluding the audio and video portions. The audio portion
`is applied to a program audio scrambler 42 and to a
`video sync detector 44. The video sync detector 44
`detects an appropriate synchronization pulse in the
`video signal, e.g., the vertical sync pulses, and supplies
`the sync pulse to a scramble code generator 46 and to
`the program ID code unit 18. The scramble code gener-
`ator 46 supplies a video scramble control signal VCS to
`the program video scrambler 42 and an audio scramble
`control signal ACS to the program audio scrambler 40.
`The program signal is thus scrambled to produce a
`scrambled audio signal SAUD and a scrambled video
`signal SVID in a conventional manner. In addition, the
`scramble code TSC is generated by the scramble code
`generator 46 so as to identify the manner in which the
`program signal has been scrambled.
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`6
`As was previously mentioned, the program ID code
`unit 18 receives the sync signal from the video sync
`detector 44 and generates the program code signal
`TPC. In this connection, a program ID code selector 48
`may be provided to control the generation of a particu-
`lar program code by a program ID code generator 50.
`Thus, the station operator can select a particular code
`for a particular program in this manner.
`The scrambled audio and video signals together with
`the scrambled code and program code are supplied to
`the scrambled program signal transmitter 16 comprising
`a signal combiner 52 and conventional modulators and
`transmitters 54. The signal combiner 52 receives the
`scrambled video, scramble code and program code
`signals and combines these signals in a conventional
`manner to produce a signal such as that illustrated in
`FIG. 2. This combined signal
`is then applied to the
`modulators and transmitters 54 together with the
`scrambled audio signal for modulation of these signals
`onto a suitable carrier wave for transmission.
`It will thus be appreciated from the diagram of FIG.
`3 that the video sync detector 44 detects the appropriate
`synchronization pulse in the video signal in order to
`trigger the scramble code generator 46 and the program
`ID code generator 50 at appropriate times. For exam-
`ple, the video sync detector 44 preferably detects the
`vertical sync pulse during the vertical retrace interval
`of the video signal. This vertical sync pulse triggers the
`scramble code generator 46 in order to cause the pro-
`gram video signal to be inverted or passed uninverted at
`an appropriate time. In addition, the detected sync sig-
`nal triggers the scramble code generator and the pro-
`gram ID code generator in order to synchronize the
`generation of the scramble code and program code
`signals TSC and TPC with the occurrence of the verti-
`cal retrace interval. The audio scramble control signal
`ACS generated by the scramble code generator 4-6 may
`be any suitable control signal and need not be synchro-
`nized to the video synchronization pulses.
`The signal combiner 52 conventionally combines the
`video and code signals and the modulators and transmit-
`ters 54 provide appropriate modulated signals for either
`broadcast or cable transmission.
`Referring now to FIG. 4, the program signal receiver
`32 at the subscriber station may include a conventional
`tuner 56 and a conventional demodulator 58. The
`scrambled program signal is supplied to the tuner 56 and
`to the demodulator 58 for recovery of the scrambled
`audio and scrambled video signals. The scrambled
`video signal, of course, contains the program and
`scramble codes in addition to video information. Con-
`trol of the tuner 56 and thus selection of a particular
`carrier frequency may be accomplished in a conven-
`tional manner by a control knob on the subscriber con-
`trol unit 30. The control unit 30 may therefore be re-
`ferred to as a program select and accept control since
`this control also may provide for the application of an
`accept signal ACC to the control and storage unit 26 as
`an indication that the subscriber has assumed the obliga-
`tion to pay for a particular program to which the equip-
`ment is tuned.
`
`The scrambled audio signal is supplied to a program
`audio unscrambler 60 and the scrambled video signal is
`supplied both to a program video unscrambler 62 and to
`a code detector 64 in the control and storage unit 26.
`The code detector 64, when enabled by the accept sig-
`nal ACC, detects the received scramble code RSC and
`the received program code in the video signal. The
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`7
`received scrambled code is supplied to a scramble code
`comparator 66 and the received program code is sup-
`plied to a conventional signal storage device 68 for
`storage and later recall by the access unit 32.
`The scramble code comparator 66 receives a stored
`scramble code signal SSC from the signal storage de-
`vice 68 and generates the video and audio unscramble
`control signals VCS’ and ACS’, respectively. These
`two signals are supplied to the respective program
`video unscrambler 62 and the program audio unscram-
`bler 60 in order to reconstitute the scrambled video and
`audio signals to their original form prior to scrambling
`by the program signal scrambler 14 at the central station
`equipment. This unscrambling process may take the
`form, for example of that illustrated and described in
`previously referenced U.S. Pat. No. 3,824,332. Thus, for
`example, when the received scramble code RSC is com-
`pared to the stored scramble code SSC and is identified
`as an invert signal, the VCS’ signal causes the program
`video unscrambler 62 to invert the subsequent frame of 20
`video signals. Similarly, when the received scramble
`code is compared with the stored scramble code and is
`identified as a non-invert signal,
`the video signal
`is
`passed by the program video unscrambler 62 in an unin-
`verted form.
`The access unit 32 is connected to the telephone lines
`as was previously described and provides access be-
`tween the billing data gathering computer 20 and the
`signal storage device 68. The subscriber station equip-
`ment may be accessed in any one of the various ways
`disclosed in the previously referenced copending patent
`applications of Block and Martin such as through the
`timed placement of a call from the accessunit 32 to the
`computer 20 (e.g., the placement of a call on a monthly
`basis). Similarly, when the signal storage device 68 is
`full and can store no more program codes, the access
`unit 32 may place a call to the data gathering computer
`20 to transfer billing information thereto.
`In this connection, the computer 20 and access unit 32
`may be connected over the telephone lines through
`conventional telephone switching equipment as com-
`manded either from the access unit 32 or from the com-
`puter 20. After the connection is effected between the
`computer 20 and the access unit 32, various data may be
`transmitted over the telephone lines.
`The computer 20 may, for example, initially com-
`mand the access unit 32 to transmit the stored program
`code signals SPC from the signal storage device 68 to
`the computer 20. This may be accomplished in any
`suitable. manner as, for example, by sending a code to
`the access unit 32 and generating an _interrogate or read
`signal INT which causes the signal storage device 68 to
`supply the stored program codes SPC to the telephone
`lines and therefore to the computer 20. Similarly, the
`computer 20 may transmit a code to the access unit 32
`commanding it to generate a strobe or write signal STR
`in order to transmit new scramble codes RSC through
`the access unit to the signal storage device 68. During
`normal operation, then, the signal storage devise may be
`supplied with scramble codes for one month’s programs
`and at the end of that month new scramble codes may
`be supplied for the next month’s programming. At the
`same time, the program codes stored in the signal stor-
`age device 68 may be accessed and transferred to the
`computer 20 so that the subscriber may be billed for
`actual programs viewed during the preceding month at
`various rates for various programs.
`
`8
`An embodiment of an access unit which provides for
`variable control of the billing period is illustrated in
`FIG. 5. The access unit 32 includes an UP-DOWN
`counter 70 which comprises a settable clock and pro-
`vides a signal to indicate when the computer 20 should
`be called to perform a billing operation. The DOWN or
`alternatively the PRESET input terminal of the counter
`70 is connected to a discriminator 72 which transmits a
`billing period length signal BPL received from the com-
`puter over the telephone lines. The discriminator 72 can
`also transmit other signals received over the telephone
`lines to other circuitry in the access unit 32 and to the
`signal storage device 68 (e.g., the INT and STR sig-
`nals). The billing period length signal BPL reduces the
`count in the counter by a predetermined amount of
`‘ alternatively presets the counter to a predetermined
`count corresponding to the length of the desired billing
`period, eg, one month.
`The UP input terminal of the counter 70 is connected
`to a clock 74. It will be obvious that the frequency of
`the output signal of the clock 74 will be determinative
`of the amount the count in the counter 70 is reduced by
`the signal BPL to obtain the desired billing period
`length.
`An output terminal of the counter 70, e.g., the zero
`count output signal,
`is connected with an automatic
`telephone dialing unit 76. After a period of time deter-
`mined by the billing period length signal BPL,
`the
`count in the counter 70 will reach a predetermined
`value such as zero and a billing time signal BTS will be
`transmitted to the dialing unit 76. This enables the dial-
`ing unit 76 and causes it to place a call to the computer
`20 to provide a connection between the computer 20
`and the access unit 32.
`Once the connection between the access unit 32 and
`the computer 20 is made,
`the previously described
`procedures associated with the billing operation are
`performed. In addition, a new billing period length
`signal BPL is transmitted to the access unit 32 to preset
`the counter 70 to a predetermined value, to establish a
`new billing period, and remove the billing time signal
`BTS. A signal lamp 77 can be connected to the counter
`70 to indicate when a billing operation is taking place.
`An output terminal of the counter 70 can be con-
`nected to the code detector 64 to provide an inhibit
`signal INHIB which prevents operation of the code
`detector after the termination of one billing period and
`prior to the beginning of the next succeeding billing
`period. The inhibit signal may also be connected to the
`clock 74 to inhibit the clock and so that the inhibit signal
`is maintained until the counter is again preset by the
`BPL signal.
`Prior to generation of the billing time signal BTS, the
`inhibit signal INHIB is in a low state. This signal is
`inverted by an inverter 78 and enables an AND gate 80.
`A second input terminal of the AND gate 80 is con-
`nected with an output terminal of the program select
`and access control 30 to receive the accept signal ACC.
`As long as an inhibit signal is not generated, the accept
`signal is transmitted to the code detector 64 by means of
`the AND gate 80.
`If, however, the count in counter 70 has reached the
`inhibit value and the inhibit signal INI-IIB‘is generated,
`the AND gate 80 will be disabled. The subscriber will
`not be able to actuate the code detector 64 to receive a
`broadcast program until the counter 70 is reset by a
`billing period length signal BPL from the computer. A
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`signal lamp 82 can be connected to the output terminal
`to indicate that the system is in theinhibit mode.
`The billing period length signal BPL can be varied by
`the computer to provide ameans of flexible control
`over the amount of prog