4,503,462
`[11] Patent Number:
`[19]
`United States Patent
`
`Kelly et al.
`[45] Date of Patent:
`Mar. 5, 1985
`
`[54] AUTOMATIC HOMING SYSTEM FOR A
`SUBSCRIPTION TELEVISION SIGNAL
`DECODER
`
`[56]
`
`[751
`
`_
`_
`Inventors: Gordon E-Ke1ly,A1gonc1um;Richard
`G. Merrell, Hebron; Mutsuo
`Nakanishi, Glen Ellyn, all of 111.
`
`[
`
`]
`73 Assignee: Zenith Electronics
`Glenview, 111.
`
`C
`
`orporation
`
`’
`
`[21] AWL N04 312,040
`
`[22] Filed‘
`
`Oct 169 1981
`
`Int. Cl.3 ....................... .. H04N 7/16; H04K 1/04
`[51]
`[52] U.S. Cl. .................................. .. 358/122; 358/114;
`358/117; 358/ 193.1 ; 455/185
`[58] Field of Search ................... .. 358/114, 117, 193.1,
`358/122; 455/ 185
`
`References Cited
`ENT
`MEN
`P
`U
`TS
`DOCU
`.S. AT
`3/1978 Siegle et al.
`......................... 358/117
`4,079,419
`9/1980 Thompson
`358/124
`4,222,068
`4,225,884 9/I980 Block etal.
`353/122
`4,323,922
`4/1922 Toonder
`352/117
`4,430,669
`2/1984 Cheung
`.. 358/117
`
`
`Primary Examiner—S. C. Buczinski
`[57]
`ABSTRACT
`An automatic homing system for a subscription televi-
`sion signal decoder comprises a tuning system respon-
`sive to a decoder off-command signal for operation in a
`search mode wherein successive television channels are
`sequentially tuned until a subscription television signal
`is detected. As a result, the memory circuits of the de-
`coder may be refreshed with updated subscriber autho-
`rization data in response to a transmitted subscription
`television signal even though the decoder is turned off.
`
`10 Claims, 2 Drawing Figures
`
`I6
`
`18
`
`20
`
`14
`
`DETECTOR
`
`24
`
`DECODER
`d}NTROL
`
`I2
`
`
`
`
`
`TO
`TELEVISION
`RECEIVER
`
`
`
`
`
`IZATION '
`
`I nzausrzn
`
`s‘x{E':%%'§':?§R
`RECOGNFFION
`
`36
`
`PMC Exhibit 213
`
`Apple v. PM
`|PR2016-0075
`
`Page 1
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`PMC Exhibit 2136
`Apple v. PMC
`IPR2016-00753
`Page 1
`
`

`
`U.S. Patent Mar. 5, 1985
`
`Sheet 1 of2
`
`4,503,462
`
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`PMC Exhibit 213
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`Apple v. PM
`|PR2016-0075
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`Page
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`PMC Exhibit 2136
`Apple v. PMC
`IPR2016-00753
`Page 2
`
`
`
`
`
`
`

`
`U.S. Patent Mar. 5, 1985
`
`Sheet2of2
`
`4,503,462
`
`72
`
`TUNING
`
`YES
`
`OFF COMMAND
`
`HOUSEKEEPING
`FUNCTIONS
`
`74
`
`l:-INCREMENT CHANNEL :#___ 76
`
`ROUTINES
`
`
`
`
`E DELAY Pa
`
`NO
`
`<STV CHANNE N COMMAND
`
`N0
`
`80
`
`82
`
`PMC Exhibit 213
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`Apple v. PM
`|PR2016-0075
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`Page
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`PMC Exhibit 2136
`Apple v. PMC
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`

`
`1
`
`4,503,462
`
`AUTOMATIC HOMING SYSTEM FOR A
`SUBSCRIPTION TELEVISION SIGNAL DECODER
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates generally to subscrip-
`tion television signal decoders and, more particularly,
`to an improved homing system for automatically tuning
`a subscription television signal decoder which has been
`placed in an “off-mode” by a subscriber to a subscrip-
`tion television channel for receiving current subscriber
`authorization data.
`
`In subscription television systems, television signals
`are typically transmitted to system subscribers in a
`scrambled form either along a coaxial cable or as an
`“over-the-air” broadcast. Each subscriber is provided
`with a decoder operable for unscrambling the subscrip-
`tion television signals, which unscrambeled signals are
`supplied to a conventional television receiver for view-
`ing. Quite often, the decoders are of the multi-channel
`variety wherein subscription television signals transmit-
`ted over a plurality of television channels may be selec-
`tively tuned by a conventional subscriber operated tun-
`ing system before being applied to the unscrambling
`circuits. In such cases, the subscription television signals
`are frequently grouped into a number of levels or tiers
`each representing a different programming category
`such as sporting events, movies, etc., with the decoder
`of a particular subscriber being authorized for decoding
`or unscrambling the televised subscription program-
`ming signals in selected categories, the televised sub-
`scription programming signals in the remaining unau-
`thorized categories being coupled on the television
`receiver in a scrambled and unviewable form. Of
`course, in such a system, all of the subscription televi-
`sion signals will be reproduced in a scrambled and un-
`viewable form by a normal television receiver.
`In a tiered subscription television system as described
`above, each system subscriber may selectively subscribe
`to one or more of the programming tiers as his or her
`interests dictate. To this end, each decoder, which is
`uniquely identified by a stored subscriber address code,
`includes a subscriber authorization register storing a
`subscriber authorization code identifying the program
`tiers which the subscriber is authorized to decode. The
`stored subscriber authorization code is compared to a
`program code typically transmitted during a selected
`horizontal line of the vertical intervals of a tuned sub-
`scription television signal, the program code identifying
`the programming level or tier of the accompanying
`television signal. If the stored subscriber authorization
`code and the broadcast program code result in a favor-
`able comparison, suitable decode authorization signals
`are developed in the decoder enabling the received
`television signal to be decoded and coupled to the sub-
`scriber television receiver for viewing. On the other
`hand, if a proper match between the subscriber authori-
`zation code and the transmitted program code is not
`detected, indicating that the subscriber is not authorized
`to decode television signals in the programming tier
`identified by the broadcast program code, the decode
`authorization signals are not developed and the re-
`ceived television signal is not unscrambled by the de-
`coder.
`
`From time to time, it is necessary to update or refresh
`the stored subscriber authorization codes to reflect
`changes in the programming status of the subscribers, to
`completely de-authorize delinquent subscribers or, for
`
`l0
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`example, to selectively authorize the decoding of spe-
`cial event or premium programs. Such updating or
`refreshing operations are typically accomplished by
`sequentially addressing the system decoders for enter-
`ing the updated subscriber authorization codes during
`one or more horizontal lines of the vertical intervals of
`the broadcast subscription television signals. Since a
`relatively long period of time may be required to ad-
`dress all of the decoders in the system, it has been found
`convenient to at least partially execute the memory
`refreshing operation at night while the decoders are
`turned off. To facilitate such, much of the circuitry of
`the decoders, including the tuning system thereof,
`is
`maintained in an operational status even though the
`decoder is ostensibly turned off by the subscriber. In
`addition, steps must be taken to insure that, upon being
`turned off by a subscriber, the decoder tuner reverts or
`homes to a television channel through which subscrip-
`tion television signals are being transmitted and not to a
`channel used for transmitting normal un-encoded televi-
`sion signals. In the past, decoders have been designed
`such that
`their tuning systems would automatically
`home to a selected one of a limited number, eg. four, of
`pre-programmed homing channels. Therefore, by se-
`lecting a pre-programmed homing channel which is also
`a subscription channel, the operator of the subscription
`system can insure that the tuning system of the decoder
`will home to a television channel enabling the decoders
`to be suitably refreshed when placed in an off-mode by
`the subscriber.
`
`While such limited pre-programmed homing channel
`systems generally provide adequate flexibility, they are
`subject to a number of major disadvantages. Initially,
`there is the time and expense of selecting and pre-pro-
`gramming each decoder supplied to a system sub-
`scriber. Also, and perhaps more importantly, it is quite
`possible that the system operator might not be using any
`of the pre-programmed homing channels as a subscrip-
`tion channel in which case the tuning systems of each
`decoder must be custom programmed for the particular
`application. This leads to additional costs and represents
`a highly undesirable situation.
`It is therefore a basic object of the present invention
`to provide an improved homing system for a subscrip-
`tion television signal decoder.
`It is a more specific object of the invention to provide
`a homing system for a subscription television signal
`decoder which automatically homes or reverts to a
`subscription television channel when the decoder is
`placed in an off-mode of operation.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The features of this invention which are believed to
`be novel are set forth with particularity in the appended
`claims. The invention, together with its objects and the
`advantages thereof, may best be understood by refer-
`ence to the following description taken in conjunction
`with the accompanying drawing in which:
`FIG. 1 is a block diagram showing a subscription
`television signal decoder incorporating an automatic
`homing system according to the present invention; and
`FIG. 2 is a flow chart illustrating the method of oper-
`ating the tuning system of the decoder of FIG. 1 in the
`automatic homing mode.
`
`PMC Exhibit 213
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`|PR2016-0075
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`4,503,462
`
`'
`
`3
`
`4
`selectively ate the unscrambled subscription television
`signal to reiiodulator 22 depending upon whether the
`DESCRIPTION OF THE PREFERRED
`subscriber is authorized to decode the signal. Modulator
`EMBODIMENT
`22 modulates the decoded baseband signal onto a stan-
`Referring to FIG. 1, there is illustrated a subscription
`television signal decoder operable for unscrambling a 5 dard television channel carrier and couples the modu-
`broadcast RF television signal. The scrambled subscrip-
`lated television signal to the antenna terminals of a con-
`tion television signal may, for example, be derived as
`ventional television receiver for viewing.
`taught in U.S. Pat. No. 4,222,068 to Thompson by modi-
`Subscriber operation of the decoder is facilitated by a
`fying a standard NTSC television signal by suppressing
`decoder control unit 24. Decoder control 24, which
`the amplitude of randomly selected horizontal blanking 10 may comprise either a remote controlled hand held
`and synchronization pulses during the fields of the
`device or a control unit integral with the decoder, pro-
`video signal. As a result, the horizontal deflection sys-
`vides means for controlling such functions as channel
`tem of a normal television receiver will lock on random
`selection, ON/OFF mode selection, etc. Of particular
`video peaks during the active or video trace line por-
`significance in relation to the present invention is the
`tions of the video signal rather than on the actual hori- 15 ON/OFF mode selection signal developed on an output
`zontal synchronization pulses resulting in the produc-
`conductor 26 of decoder control 24. The ON/OFF
`tion of a scrambled video image on the viewing screen
`mode selection signal, which is coupled to an input of
`of the television receiver. In addition, the ability of the
`tuning system 12 and also to 1 input of AND gate 28,
`television receiver to use the color reference burst asso-
`assumes a logical 1 state when the decoder is turned on
`ciated with the horizontal synchronization signals is 20 by the subscriber and assumes alogicalOstate when the
`severely degraded causing inaccurate color reproduc-
`decoder is turned off by the subscriber. When the de-
`tion. In addition, a program code identifying the pro-
`coder is turned on causing the ON/OFF mode selection
`gramming tier of the accompanying television signal is
`signal to assume a logical 1 state, the decoder is opera-
`encoded in a horizontal line of each vertical interval of
`ble for tuning and decoding a subscription television
`the television signal. Also, one or more vertical interval 25 signal broadcast over a selected television channel and
`horizontal lines of the subscription television signal are
`for coupling the decoded signal to a television receiver
`normally used for transmitting the subscriber address
`via modulator 22. As will be explained in further detail
`and authorization codes. The latter codes are transmit-
`below, the decoder is also operable for tuning a nonsub-
`ted on a serial basis so that the decoder of each sub-
`scription television signal transmitted over a selected
`scriber may be individually addressed and refreshed 30 television channel for coupling to the television re-
`with an updated subscriber authorization code from
`ceiver via modulator 22. On the other hand, when the
`time to time.
`decoder is turned off causing the ON/OFF mode selec-
`In one known subscription television system, for ex-
`tion signal to assume a logical 0 state, video switch 20 is
`ample, a five bit program code identifying the program-
`disabled whereby a blanked video signal is coupled to
`ming tier of the accompanying subscription television 35 the input of modulator 22.
`signal is transmitted during horizontal line 13 of each
`The composite baseband signal developed at the out-
`vertical interval while horizontal lines 10, 11 and 12 are
`put of video detector 16 is also coupled to the input of
`each used to transmit a twenty bit subscriber address
`a first data gate 30 which is adapted for gating the our-
`code together with a five bit subscriber authorization
`rent program code developed.on each horizontal line 13
`code. In this manner, the decoders may be addressed 40 of the subscription television signal to ashift register 32.
`one at a time for updating the stored subscriber authori-
`The composite baseband video signal is also coupled to
`zation codes which are compared with the transmitted
`the input of a second data gate 34 which is adapted for
`program code on horizontal
`line 13 to determine
`gating the subscriber address codes transmitted on hori-
`whether a particular subscriber is authorized to decode
`zontal lines 10, 11 and 12 to the input of a subscriber
`the received subscription television signal.
`45 address recognition circuit 36 and the accompanying
`With further reference to FIG. 1, the illustrated de-
`subscriber authorization codes to the input of a sub-
`coder comprises an antenna 10 adapted for intercepting
`scriber authorization register 38. If a transmitted sub-
`broadcast RF television signals which may comprise
`scriber address code corresponds to the stored sub-
`either scrambled subscription television signals as de-
`scriber address code identifying a particular subscriber,
`scribed above or normal unscrambled television signals. 50 an output is developed by recognition circuit 36 causing
`The intercepted broadcast television signals are coupled
`subscriber authorization register 38 to load the associ-
`from antenna 10 to a conventional
`television signal
`ated transmitted subscriber authorization code. By the
`tuning system 12 which, as well known in the art, con-
`foregoing means, it will be recognized that the subscrib-
`verts the received RF television signals to a suitable
`er’s stored authorization code may be updated from
`intermediate frequency signal. The intermediate fre- 55 time to time by the subscription television signal to
`quency signal developed at the output of tuning system
`reflect changes in his or her authorization status.
`12 is conventionally applied through an intermediate
`The current program code stored in shift register 32
`frequency amplifier 14 to the input of a video detector
`and the subscriber authorization code stored in register
`16 whose output therefore comprises a baseband repre-
`38 are coupled to the inputs of a code comparator 40.
`sentation of the received television signal.
`60 Code comparator 40 includes a first output 42 which is
`The composite baseband video signal developed at
`coupled to a second input of AND gate 28 and a second
`the output of video detector 16 is applied to the input of
`output 44 which is coupled to one input of an OR gate
`a video unscrambler 18 and therefrom through a video
`46, the output of OR gate 46 being coupled to the third
`switch 20 to the input of a modulator 22. Video un-
`and final input of AND gate 28. A second input to OR
`scrambler 18 is adapted for unscrambling the baseband 65 gate 46 is derived from a conductor 48. Output 42 of
`code comparator 40 assumes a logical 0 state if the
`subscription television signal such as, for example, by
`restoring horizontal sync thereto. As will be explained
`subscriber authorization code stored in register 38 cor-
`in further detail hereinafter, video switch 20 is used to
`responds to a value representing that the subscriber is
`
`PMC Exhibit 213
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`4,503,462
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`5
`not authorized to decode any of the programming tiers
`and assumes a logical l state if the subscriber is autho-
`rized to decode subscription television signals in one or
`more of the program tiers. Output 44 of code compari-
`tor 40 assumes a logical 1 state if a comparison between
`the transmitted program code and the stored subscriber
`authorization code reflect that the subscriber is autho-
`rized to decode the transmitted subscription television
`signal and otherwise assumes a logical 0 level. As will
`be explained in further detail below, the signal on con-
`ductor 48 assumes a logical 0 state whenever the de-
`coder is receiving a subscription television signal and
`assumes a logical
`1 state when receiving a standard
`television signal.
`In view of the foregoing, it will be appreciated that
`three separate conditions must be satisfied before AND
`gate 28 will enable video switch 20 for passing baseband
`video signals from video unscrambler 18 to modulator
`22. Initially, the decoder must be turned on so that the
`ON/OFF mode selection signal is in a logical 1 state.
`Secondly, the stored subscriber authorization code must
`reflect a value such that the subscriber is authorized for
`decoding at least one programming tier so that the sig-
`nal developed on output 42 of code comparator 40 is
`logical 1. And, finally, the output of OR gate 46 must be
`logical 1,
`this latter condition being satisfied either
`when a nonsubscription television signal is being trans-
`mitted or, if a subscription television signal is being
`transmitted, when the transmitted program code
`matches the stored subscriber authorization code such
`that the signal developed on output 44 of code compara-
`tor 40 is logical 1.
`The development of the subscription television detec-
`tion signal on conductor 48 is facilitated by coupling the
`output of data gate 34 to the input of a data detector 50.
`Data detector 50 is adapted for detecting the presence
`of the subscriber address and authorization codes trans-
`mitted during horizontal lines 10, 11 and 12 and devel-
`ops an output signal
`in response thereto enabling a
`counter 52 during these three horizontal scanning lines.
`Counter 52 is clocked in response to the horizontal sync
`pulses of the transmitted television signal, which pulses
`are derived from the output of a sync stripper 54 con-
`nected to the output of video detector 16. The compos-
`ite sync signal developed at the output of sync stripper
`54 is also coupled through an integrator 56 to the reset
`input of counter 52 such that the counter is reset in
`response to the integrated vertical sync pulse at the
`beginning of each field of video. Therefore, counter 52
`is reset at the beginning of each video field and enabled
`for counting the horizontal sync pulses associated with
`horizontal lines 10, 11 and 12 when a subscription tele-
`vision signal is being transmitted. After counting these
`horizontal sync pulses, the enable input of the counter is
`internally latched so that the counter continues count-
`ing horizontal sync pulses.
`A decoder 58 decodes the state of counter 52 assumed
`in response to the horizontal sync pulse associated with
`horizontal scanning line 20 and couples a logical l sig-
`nal for the duration of this line to the input of an integra-
`tor circuit through a resistor 60. The integrating circuit
`comprises a grounded emitter transistor 62 whose base
`is connected to resistor 60 and whose collector is con-
`nected to a source of supply potential through a resistor
`64. The collector of transistor 62 is also connected to a
`grounded capacitor 66,
`to a control input of tuning
`system 12 and to conductor 48.
`
`l0
`
`15
`
`20
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`25
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`30
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`6
`In operation, when a nonsubscription television sig-
`nal is being transmitted, the output of decoder 58 is
`continuously logical 0 so that transistor 62 is held in a
`cut off state allowing capacitor 66 to charge and remain
`at the supply potential. As a consequence, a logical
`1
`signal is developed at the collector of transistor 62 rep-
`resenting that a normal of nonsubscription television
`signal is being transmitted. However, in response to the
`transmission of a subscription television signal, transis-
`tor 62 is rendered conductive during horizontal scan-
`ning line 20 of each video field allowing capacitor 66 to
`discharge to a level so as to present a logical 0 signal at
`the collector of transistor 62 representing that a sub-
`scription television signal is being transmitted. Compo-
`nent values are selected such that capacitor 66 will
`discharge at a relatively rapid rate during horizontal
`lines 20 but charge at a relatively slow rate so that the
`potential at the collector of transistor 62 will continu-
`ously reflect a logical 0 signal level as long as the sub-
`scription television signal is being transmitted.
`As mentioned previously, when the decoder is being
`operated in its ON mode, i.e. the ON/OFF mode selec-
`tion signal on conductor 26 being logical l, the tuning
`system 12 is effective for tuning the television signal
`transmitted over a selected television channel. If the
`tuned television signal is a subscription television signal,
`the subscriber address and authorization codes transmit-
`ted during horizontal lines 10, 11 and 12 of the televi-
`sion signal may be used to update authorization register
`38 as described above. If, on the other hand, the tuned
`television signal is a nonsubscription signal,
`then, of
`course, the memory updating operation cannot be car-
`ried out. Due to the large amount of time required to
`update the entire subscriber population,
`it has been
`found convenient to at least partially perform the mem-
`ory updating operation at night or at any other time
`when the decoders are turned off. However, in order to
`make this feasible, means must be provided to insure
`that, upon being turned off, the tuning system of the
`decoder reverts or homes to a subscription television
`channel. The present
`invention is particularly con-
`cerned with an improved automatic homing system
`designed for homing to a subscription television chan-
`nel after the decoder has been turned off regardless of
`the particular channels used to transmit subscription
`television signals.
`When the decoder is turned offf, the ON/OFF mode
`selection signal developed on conductor 26 goes to
`logical 0, this logical 0 signal disabling video switch 20
`and also being supplied to an input of tuning system 12.
`In addition, one or more indicator lights, e.g. channel
`number LED’s may be extinguished in response to the
`logical 0 ON/OFF mode selection signal. The remain-
`ing circuitry of the decoder, however, remains fully
`operational. Tuning system 12 includes means, such as a
`suitably programmed microprocessor, for sensing the
`states of the logic signals coupled to its inputs from
`conductor 26 (the ON/OFF mode selection signal) and
`from the collector of transistor 62 (the subscription
`television detection signal). If the ON/OFF mode selec-
`tion signal is logical 1, tuning system 12 operates in a
`normal fashion to tune a selected television channel.
`However, if the ON/OFF mode selection signal is logi-
`cal 0, then tuning system 12 is placed in a special auto-
`matic homing mode. In this homing mode, ‘tuning sys-
`tem 12 increments through successive television chan-
`nels as long as a logical 1 signal is coupled to its control
`input from the collector of transistor 62. However, as
`
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`7
`soon as the signal at the collector of transistor 62 as-
`sumes a logical 0 state, the sequential operation of the
`tuner ceases and tuning is maintained for the channel
`causing the development of the logical 0 signal at the
`collector of transistor 62. Therefore, in response to the 5
`decoder being turned off, tuning system 12 is operated
`in a signal
`searching mode sequentially stepping
`through successive nonsubscription television signals
`until a subscription television signal is detected. There-
`after, tuning system 12 remains tuned to the detected 10
`subscription television signal facilitating the refreshing
`or updating of the decoder’s memory circuits.
`FIG. 2 is a flow chart illustrating a method of pro-
`gramming tuning system 12 for realizing the foregoing
`operation. The tuning system continuously samples the 15
`ON/OFF mode selection signal developed on conduc-
`tor 26 and makes a decision 70 as to whether the signal
`is logical 1 (decoder on mode) or logical O (decoder off
`mode). If the signal is logical 1, indicating that the de-
`coder is in its on mode, the normal tuning routines 72 of 20
`the program are executed for tuning a selected televi-
`sion channel. If, on the other hand, a logical 0 signal is
`detected, indicating that the decoder is in its off mode,
`a number of housekeeping functions 74 are executed.
`The housekeeping functions include extinguishing any 25
`LED indicators and disabling video switch 20. Thereaf-
`ter, an instruction 76 is executed incrementing the tuner
`to the next successive television channel and a short
`period of time is allowed to transpire per an instruction
`78 to allow the decoder to stabilize at the signal trans- 30
`mitted over the tuned channel. The next successive
`channel to which the tuner is incremented in response
`to instruction 76 is either the channel characterized by
`the next successive channel number or,
`in the case
`where the tuner is tuned to the channel having the 35
`highest channel number, the channel characterized by
`the lowest channel number. Thus, by repetetively per-
`forming instruction 76, it is possible to continuously
`sequence through all of the channels in a cyclical man-
`ner.
`
`40
`
`Following the short delay represented by instruction
`78, a decision 80 is made to determine whether the
`tuned television signal is a subscription television signal,
`. this decision being based on the logic state of the signal
`coupled to tuning system 12 from the collector of tran- 45
`sistor 62. If the signal is logical 1, indicating that the
`tuned television. signal is a nonsubscription signal, a NO
`decision is reached causing instructions 76 and 78 to be
`repeated. The loop consisting of instructions 76 and 78
`and decision 80 will therefore be continuously repeated 50
`until a logical 0 signal, representing that the tuned tele-
`vision signal is a subscription signal, is detected at the
`collector of transistor 62. In the latter case, decision 80
`results in a YES response whereby channel tuning is no
`longer incremented. At this time, tuning system 12 is 55
`tuned to a subscription television channel enabling the
`updating of its memory circuits as previously described.
`Tuning system 12 remains tuned to the subscription
`television channel so long as the ON/OFF mode selec-
`tion signal remains logical O as determined by decision 60
`82. However, as soon as this signal goes to logical 1,
`representing that the decoder has been turned on, con-
`trol is returned to the normal tuning routine 72.
`What has thus been shown is an improved automatic
`homing system for a subscription television decoder. 65
`The system automatically homes to a subscription tele-
`vision channel by operating in a search mode wherein
`successive television channels are tuned until a subscrip-
`
`4,503,462
`
`8
`tion television channel is detected whenever the de-
`coder is turned off. As a result, the memory circuits of
`the decoder may be updated in response to a transmitted
`subscription television signal even though the decoder
`is turned off.
`While a particular embodiment of the invention has
`been shown and described, it will be obvious to those
`skilled in the art that changes and modifications may be
`made without departing from the invention in its
`broader aspects. Therefore, the aim in the appended
`claims is to cover all such changes and modifications as
`fall within the true spirit and scope of the invention.
`What is claimed is:
`
`1. An automatic homing system for a television signal
`decoder, said television signal decoder including a
`memory adapted for storing subscriber data transmitted
`during selected horizontal lines of the vertical intervals
`of each of a plurality of scrambled television signals
`broadcast over a plurality of respective television chan-
`nels, comprising:
`control means selectively operable for establishing a
`decoder on-mode signal representing that said de-
`coder is in use or a decoder off-mode signal repre-
`senting that said decoder is not in use;
`tuning means responsive to said on-mode signal for
`tuning a selected television channel;
`subscriber data recognition means responsive to the
`information content of said subscriber data for
`presenting subscriber data addressed to said de-
`coder for storage in said memory; and
`subscriber data presence detecting means coupled to
`said tuning means for developing a control signal in
`response to a tuned television signal being charac-
`terized by the presence of said subscriber data inde-
`pendent of the information content represented
`thereby;
`said tuning means being responsive to said off-mode
`signal for sequentially tuning successive television
`channels until a channel is tuned which results in
`the development of said control signal, whereby
`said memory may be updated by said subscriber
`data in response to the establishment of said off-
`mode signal.
`2. An automatic homing system according to claim 1
`wherein said tuning means includes a control input, said
`tuning means being responsive to said off-mode signal
`and to a first logic level signal applied to said control
`input for sequentially tuning successive television chan-
`nels and responsive to said off-mode signal and to a
`second logic level signal applied to said control input
`for tuning a single television channel.
`3. An automatic homing system according to claim 2
`wherein said detecting means includes an output cou-
`pled to said tuning means control input, said detecting
`means output being characterized by said second logic
`level signal in response to a tuned television character-
`ized by the presence of said subscriber data and other-
`wise being characterized by said first logic level signal.
`4. An automatic homing system according to claim 3
`wherein said detecting means comprises capacitive
`means coupled to said detecting means output, means
`for discharging said capacitive means to a value corre-
`sponding to said second logic level signal in responselto
`a tuned television signal being characterized by the
`presence of said subscriber data and means otherwise
`charging said capacitive means to a value correspond-
`ing to said first logic level signal.
`
`PMC Exhibit 213
`
`Apple v. PM
`|PR2016-0075
`
`Page
`
`PMC Exhibit 2136
`Apple v. PMC
`IPR2016-00753
`Page 7
`
`

`
`4,503,462
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`9
`5. An automatic homing system according to claim 4
`wherein said means for discharging comprises switch-
`ing means coupled to said capacitive means and means
`for rendering said switching means conductive for dis-
`charging said capacitive means for a relatively short
`time interval at least once during each field of a stan-
`dard television signal.
`6. For use in a television subscription system in which
`subscriber data is encoded into the vertical intervals of
`each of a plurality of scrambled RF television signals
`transmitted over respective television channels, a de-
`coder comprising:
`control means selectively operable for establishing a
`decoder on-mode signal representing that said de-
`coder is in use or a decoder off-mode signal repre-
`senting that said decoder is not in use;
`tuning means operable for converting a broadcast RF
`television signal to a corresponding baseband tele-
`vision signal;
`memory means adapted for storing subscriber data
`presented thereto;
`subscriber data recognition means responsive to the
`information content of said subscriber data for
`presenting only the subscriber data addressed to
`said decoder for storage in said memory means; and
`subscriber data presence detecting means coupled to
`said tuning means for developing a control signal in
`response to said baseband television signal being
`cha