United States Patent
`Sechet et al.
`
`[191
`
`4,354,20fi
`[11]
`[45] Oct. 12, £982
`
`
`
`3.991718 12/1916 Ricketts
`4,025,943 5/ 19?? Loshin ........ ..
`_ 4,045,314
`8/1917 Hartung et aI
`4,081,832
`3/1978 Sherman ........ ..
`4,214,230 7/1980 Fak at al.
`
`
`
`455/2
`353/ 122
`358/124
`353/ 122
`340/149 A
`
`Primary Examiner—S. C. Buczinski
`
`[57]
`
`ABSTRACT
`
`{54] TELEVISION SYSTEM WITH ACCESS
`CONTROL
`
`[75}
`
`Inventors: Claude Seehet, Rennes, France;
`Gerard Bshouueau, 14, rue Théodore'
`Botrel, 35830 Betton, France; Louis
`C. Guillou, Saint Erblon, France
`Etshlissenietlt Public (1e Diffusion
`Dit: Teledifl’usion de Finance,
`Montrouge; Gerard Bahonneau,
`Betton, both of France
`
`[73] Assignees:
`
`[21] App]. No: 153,499
`
`J'm‘ 11’ 198“
`[22] “lad:
`[30]
`I Foreign Application Priority Data
`Jun. 15, 1979 [FR]
`France
`
`79 15400
`
`Int. 01.3 ......................... HMN 7/16; H04K 1/04
`[51]
`[52] U.S. Ci.
`358/122; 358/114;
`358/345. 358/347
`[53] Field of Search ................. 353/114 122', 86, 345,
`,
`358/347
`
`[55]
`
`_
`Referenws (mad
`U.S. PATENT DOCUMENTS
`3,538,243 11/1970 Shanahan et a].
`3,934,079 1/1976 Barnhart
`3,956,615 5/1976 Anderson et al.
`
`353/124
`353/86
`
`340/152 R
`
`5 Claims, 5 Drawing Figures
`
`|— w * W sTéN‘E mom-1
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`A television system with access control comprises a
`transmitter and receivers. The transmitter comprises a
`video signal and sound signal formation circuit, means
`for transmitting these signals and a jamming circuit
`using a service key. Each receiver comprises means for
`receiving the transmitted signals, means for the display
`of the picture and for restoring the sound and an unjam-
`wing Circuit “Ounac‘ed *0 “18 mptic’“ means and
`working with the service key.
`I
`1
`.
`.
`.
`.‘ a 5" comprises a WWW?“ management “in”? “d
`1n the transmitter 11 digital signal generator, a Circuit for
`the formation of digital messages and a data broadcast-
`ing system and in the receiver a subscription card, an
`extraction circuit for the data, and a circuit for restoring
`the service key. There is also at least one subscription
`card loading station connected to the subscription man»
`agement center-
`
`I DIGITAL
`MESSAGES
`_
`,2 asst“
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`
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`
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`
`CCT PMC Exhibit 2200
`
`Apple v. PMC
`|PR2016-01520
`
`Page 1
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`PMC Exhibit 2200
`Apple v. PMC
`IPR2016-01520
`Page 1
`
`

`

`
`
`US. Patent
`
`Oct. 12, 1982
`
`Sheet 1 of 4
`
`4,354,201
`
`SUBSCRIPTION
`
`BROADCASTING
`'
`SYSTEM
`
`SOUND
`
`MANAGEMENT
`
`
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`FORMATION
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`PMC Exhibit 2200
`
`Apple v. PMC
`|PR2016-01520
`
`
`
`Page 2
`
`
`PMC Exhibit 2200
`Apple v. PMC
`IPR2016-01520
`Page 2
`
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`PMC Exhibit 2200
`Apple v. PMC
`IPR2016-01520
`Page 3
`
`
`

`

`US. Patent
`
`Oct. 12, 1982
`
`_
`
`Sheet 3 of4
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`4,354,201
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`Apple v. PMC
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`
`

`

`1
`
`4,354,201
`
`TELEVISION SYSTEM WITH ACCESS CONTROL
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to a television system
`with access control using a variable electronic key.
`The problem of access control of broadcast informa-
`tion mainly consists of the jamming of information on
`transmission by means of an appropriate key, as well as
`unjamming or deciphering on reception by means of an
`identical key, which is only in possession of users who
`have regularly paid a subscription fee.
`Numerous television systems are already known
`which are equipped with jamming means on transmis-
`sion and unjamming means on reception. Such systems
`are more particularly described in French Pat. No. 106
`670, German Pat. No. l 907 580, French Patent Appli-
`cation No. 75 34029 filed on Nov. 3, ‘1975 in the joint
`name of the French State and Telediffusion de France,
`French Pat. No. l 034 776, German Pat. No. l 254 676
`and [1.5. Pat. Nos. 2,510,046, 2,619,530, 2,892,882 and
`2,972,009.
`The jamming processes used in these systems are
`based on the introduction of a displacement of the posi-
`tion of the line synchronization pulse on a periodic
`reversal of the complete signal and on the polarity
`change of the video signal or on a combination of these
`operations. In all these processes it is necessary for the
`receivers to receive in some way or the other signals
`making it possible to restore the key necessary for cov-
`ering the clear information.
`The present invention relates to a television system of
`this type, but in which the key which permits unjam-
`ming is transmitted to the receivers in an original and
`advantageous manner.
`In the prior art systems the transmission of this key
`does not give entire satisfaction because it is not gener-
`ally compatible with the recently developed digital
`services and which are being or will be offered to view-
`ers. They consist more particularly of three systems: a
`system for digital acquisition and television display of
`pictures organised in writing pages, a system for inter-
`active terminal for teletext with call-in by numbering,
`and a system for programmed recording of transmis-
`sions on command from the sources.
`The first system consists of a broadcast videotex sys-
`tem making it possible to insert alphanumeric informa«
`tion organized in pages and in magazines on television
`channels. The second comprises an interactive videotex
`system compatible with the first system and giving ac-
`cess to data bases (general information, lists, etc.) and to
`interactive services (transactions, messages, instruction)
`by the telephone system. The third system is a pro-
`gramme message system consisting of offering by means
`of a data broadcasting channel the remote control from
`a transmission source of the recording action by a re-
`ceiver (e.g. a magnetoscope) of a preselected television
`programme.
`For broadcasting information these three systems use
`means and a process of broadcasting of digital data1
`which is compatible with the broadcasting of the televi-
`sion signal.
`BRIEF SUMMARY OF THE INVENTION
`
`The present invention relates to an access control
`means having a complete compatibility with these dif-
`ferent systems.
`'
`
`
`
`2
`To this end the system according to the invention has.
`two essential features:
`
`(1) In the first place it uses a double key system,
`namely with-a service key K making it possible to jam
`information and which changes in a random manner at
`relatively shOrt intervals of approximately a few min-
`utes, and a subscription key which can assume several
`values C; depending on the type of subscription, said
`key also changes in a random manner but at longer
`intervals of approximately one month. This subscription
`key appears on a subscription card introduced into each
`receiver. The two keys K and Cgare combined on trans-
`mission for forming messages Mg.
`_
`(2) Secondly the messages Miand not the actual ser-
`vice key K are-transmitted from the transmitter to the
`receivers. This transmission takes place in accordance
`with the aforementioned digital data broadcasting pro-
`cess, which gives the system compatibility with all digi-
`tal services based on this procedure. On reception the
`messages M; received are combined by the subscription
`key C: supplied by a subscription card, making it possi-
`ble to restore the key K necessary for unjamming the
`signal received.
`More specifically the present invention relates to a
`television system provided with access control means
`and which comprises a transmitter and receivers, trans-
`mitter comprising a formation circuit for a videosignal
`organized in lines and in fields and a sound circuit, as
`well as a transmission means for said signals, each re-
`ceiver comprising a reception means for the transmitted
`signals and means for the visual display of the picture
`and the restoration of the sound, wherein it also com-
`prises:
`(A) a subscription management centre comprising the
`means for generating a plurality of digital signals consti-
`tuting subscription keys Cschanging in random manner
`at relatively long intervals of approximately one month;
`(B) a transmitter comprising:
`(a) a digital signal generator constituting a service
`key K, said key changing in random manner at rela-
`tively short intervals of approximately a few minutes,
`(b) a circuit for the formation of digital messages M,-
`obtained from the subscription keys C: and the service
`key K by an algorithm parametered by the subscription
`key, i.e. M5=Fcy (K), said circuit supplying the same
`number of messages as there are subscription keys, said
`messages changing with the service key,
`(c) a system for broadcasting digital data able to insert
`messages M,- in the field blanking intervals of the video
`signal,
`(d) a jamming circuit using the service key K, said
`jamming circuit receiving the video and/or sound sig-
`nal and supplying jammed video and/or sound signals
`which are then transmitted to the transmission means,
`said jamming not affecting the messages contained in '
`the field blanking intervals;
`(C) in each receiver are provided:
`(a) a subscription card on which is entered a signal
`corresponding to at least one of the subscription keys
`Cr,
`(b) a circuit for the extraction of the digital data con-
`tained in the signal received, said circuit restoring the
`messages Mr,
`(c) a circuit for restoring the Service key receiving on
`the one hand messages supplied by the preceding circuit
`and on the other the subscription key Cssupplied by the-
`subscription card, said circuit performing an algorithm
`K=Gcg (Mg) making it possible to restore the signal
`
`10
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`65
`
`PMC Exhibit 2200
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`|PR2016-01520
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`

`
`
`3
`corresponding to the service key K used in the transmit-
`ter,
`
`4
`FIG. 5—the organization of the key change detection
`means.
`-
`
`4, 354,201
`
`(d) an unjamming circuit connected on the one hand
`to the reception means from where it receives the
`jammed video and optionally sound signals and on the
`other hand 'to the restoration circuit from where it re-
`ceives the service key K, said unjamming circuit sup-
`plying unjammed video and optionally sound signals
`which are then transmitted to the means for the display
`of the picture and the restoration of sound;
`(D) at least one subscription card loading station,
`which is connected to the subscription management
`centre from which it-receives signals corresponding to
`the different subscription keys C,- generated by the said
`centre, each station being able to temporarily receive
`subscription cards and write therein one of the subscrip-
`tion keys Cf.
`'
`'
`Preferably the jamming circuit comprises a pseudo-
`random sequence generator re-initialized at the start of
`each field by the service key K and supplying a digital
`jamming signal at the start of each line, and a video and
`' optionally sound signal conversion circuit, the conver-
`sion being carried out by this circuit being defined by
`the digital signal supplied by the pseudo-random se-
`quence generator.
`
`'
`
`In this case the unjamming circuit comprises a pseu-
`do-random sequence generator identical to that of the
`jamming circuit and in the same way re-initialized at the
`start of each field by the service key K and supplying an
`unjamming digital signal at the start of each line and a
`circuit able to carry out the reverse conversion to that
`of the jamming circuit on the video and optionally
`sound signal, said conversion being determined by the
`digital unjamming signal supplied .by the pseudo-ram
`dom sequence generator.
`The jamming operation on transmission can be of any
`known type and particularly in accordance with the
`processes described in the documents referred to here-
`inbefore. However, according to an advantageous vari-
`ant a means based on a circular permutation of the sam-
`ples to be jammed is used.
`Naturally the jamming operation can affect both the
`picture and the sound. With regard to the transmission
`of sound it can be carried out either by an ordinary
`sound channel, or a digital channel using the field blank-
`ing intervals and operating in accordance with the digi-
`tal data broadcasting procedure, or a digital channel
`using the line blanking intervals, or a digital channel
`using supplementary signals inserted in the chromi-
`nance colour bursts.
`The means used for the transmission of sound can be
`marked by means of bits forming part of the service key
`K.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention is described in greater detail hereinaf-
`ter relative to non~limitative embodiments and the at-
`tached drawings, wherein show:
`FIG. l—a block diagram of a television system with
`access control according to the invention.
`FIG. 2—diagrammatically jamming means using a
`circular permutation of samples.
`FIG. 3—-the standard preferably adopted for the
`videosignal.
`FIG. 4—diagrammatically the locations in the field
`synchronization signal of the signals indicating a change
`of key.
`
`S
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`The system shown in FIG. 1 firstly comprises a sub-
`scription management centre 10 which generates a plu-
`rality of signals constituting subscription keys Cg, which
`change in a random manner at relatively long intervals
`of approximately one month.
`The actual television system is organized around the
`transmitter 12 and has a plurality of receivers 14.
`Transmitter 12 comprises: '
`(a) a circuit 16 for the formation of television signals
`incorporating a part relative to a videosignal carried by
`a connection 1‘7 and a part relative to the sound carried
`by a connection 19;
`(b) a generator 18 of a signal constituting a service
`key K, said key changing in a random manner at rela-
`tively short intervals of approximately a few minutes;
`(c) a circuit 20 for the formation of digital messages
`M,- from subscription key C,- generated by centre 10 and
`the service key K generated by generator 18, for which
`purpose the circuit 20 performs an algorithm parame-
`tered by the subscription keys, i.e. M=Fq (K), and
`supplies the same number of messages M; as there are
`subscription keys, said messages changing with the
`service key K;
`(d) a digital data broadcasting system 22 able to insert
`messages Mfinto the field blanking intervals of the vid-
`eosignal coming from circuit 16 by means of connection
`17;
`(e) a jamming circuit 24 using the service key K for
`jamming the video and/or sound signal, said jamming
`not affecting the messages M,- contained in the field
`blanking intervals, the jammed signal supplied by this
`circuit are then transmitted to the transmission means
`26.
`
`Each receiver 14 of the present system contains:
`(a) a broadcast signal reception means 30;
`(b) an unjamming circuit 32 connected to the recep-
`tion means 30 from which it receives the jammed video
`and optionally sound signals and which operates by
`means of the service key K, supplying the unjammed
`video and sound signals respectively carried by connec-
`tions 31 and 33;
`(c) a circuit 34 for the extraction of digital data con-
`tained in the video signal received, said circuit restoring
`messages M,- by a connection 35;
`'
`(d) a subscription card 36 on which is entered a signal
`corresponding to at least one of the subscription keys
`CF;
`(e) a circuit 38 for restoring the service key K from
`messages Misupplied by the circuit .34 and the subscrip-
`tion key C,- supplied by the subscription card 36, said
`circuit 38 performing an algorithm K=Gc,-(M.-) making
`it possible to restore the 'signal corresponding to the
`service key K used in the transmitter, said key then
`being addressed to the unjamming circuit 32;
`(1) means 40 for the display of the pictures and the
`restoration of sound.
`
`6S
`
`The system shown also has at least one loading sta-
`tion 42 suitable for the subscription card 36. This station
`is connected to the subscription management centre 10
`from which it receives signals corresponding to the
`different subscription keys Cg generated by the centre.
`Each station 42 is temporarily able to receive the sub-
`
`PMC Exhibit 2200
`
`Apple v. PMC
`|PR2016-01520
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`Page 7
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`IPR2016-01520
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`4,354,201
`
`6
`(2) air—1 is calculated being the Opposite to the modulo
`251—1 by an arithmetic programme using a variant of
`the Euclidian algorithms;
`(3) a first multiplication is performed by another
`arithmetic programme v=K1r—' modulo (251—1);
`(4) 'y is calculated, being the opposite of C modulo
`212_7—l, by a programme simiiar to that of (2);
`(5) finally the message is calculated by a. programme
`similar to (3): M=7-(v+254-a-) modulo (2127—1).
`The programmes necessary for these calculations can
`be developed by a type 8080 microprocessor of the
`INTEL Company.
`All the messages M,- in force constitute the access
`control information associated with the broadcast ser-
`vice. According to the essential feature of the invention
`this information is broadcast by the digital data broad-
`casting process at circuit 22 and is restored on reception
`at circuit 34.
`
`10
`
`IS
`
`20
`
`se.
`
`This digital data broadcasting process is known per
`
`Broadcasting is performed by bringing the data into
`packets. Each packet occupies the active part of the
`television line making it possible to ensure a good com-
`patibility with the conventional modes of use of the
`channel.
`
`As in the present invention the radio channel is allo-
`cated to a television programme, only the marginal
`resource constituted by the field blanking interval can
`be used for the transmission of messages M.
`In the digital broadcasting process each packet has
`two parts, one called the prefix and the other called the
`data block. The prefix is used for the management of the
`packet and has eight octets, two for the synchronization
`of the bits, one for the octet synchronization, three
`carry the channel code, including its protection, one
`carries the continuity symbol and the final octet de-
`scribes the format (or length) of the data block.
`The data block follows the prefix.
`Its maximum
`length is dependent upon the timing-pulse rate and the
`active duration of the line. The timing-pulse rate is
`adapted to the channel band width. The modulation
`used is the “non-return to zero” (NRZ) brought into a
`' form for adapting the spectral energy distribution to the
`transmission channeL
`When the messages M; have been transmitted and
`received by the digital broadcasting process it is neces-
`sary to reconstitute the service key K. This is the func-
`tion of circuit 38. This circuit is programmed to develop
`an algorithm K=Gci (Mg) field algorithm. The opera-
`tions are as follows:
`
`1. The message M5027 useful bits) is acquired octet
`by octet and a multiplication by Cgis carried out on the
`first field CG (2137—1). Thus a word p. is formed.
`
`25
`
`3D
`
`35
`
`40
`
`4s
`
`50
`
`55
`
`p.=.M-C modulo (rm—t).
`
`5
`scription cards and to write therein in a lasting manner
`(e.g. in a memory) one of the subscription keys Ci.
`For the purpose of illustrating the operation of this
`double key system it is possible to take the example of a
`subscription scheme using four types of subscriptions,
`i.e. one month, three months, six months and one year.
`In addition to its duration a subscription is characterized
`by the starting month. In the case of such a scheme for
`a given month and for a given service there are conse-
`quently 22 subscription keys which are likely to be used
`by users, namely one monthly key, three quarter-yearly
`keys, six half-yearly keys and twelve yearly keys.
`Every month the subscription management centre 10
`supplies transmitter 12 with a list of 22 subscription keys
`C,- for each service broadcast by this transmitter. In
`addition, it supplies loading stations 42 with another list
`of four keys for starting the following month (one
`month, three months, six months and one year), for each
`service with the subscription rates.
`A suitable machine installed at each point of sale
`enters certain of these keys in the form of subscription
`blocks 0n the cards 36. A subscription block can for
`example consist of four fields:
`.
`(l) a service code having 16 bits designating the ser-
`vice in question;
`(2) a subscription symbol of 8 bits having which char-
`acterizes the subscription for a service in question,
`whereby 2 of said bits indicate the subscription type (I,
`3, 6 or 12 months) and the 6 others indicate the subscrip-
`tion starting month ( I to 60 modulo 5 years);
`{3) a subscription key of 128 .bits which is the funda-
`mental information of the block;
`'
`(4) a cyclic redundancy code of Hi bits and relates to
`the preceding 152 bits and makes it possible to check the
`subscription block before using the same.
`Thus, a subscription block. is formed by 168 bits, i.e.
`21 octets. Such a block can easily be entered in a credit
`card-type support provided with a PROM memory .
`(Programmable Read-Only Memory) with a capacity of
`4096 bits usable for this purpose. Such a card can re-
`ceive up to 24 subscription blocks having the indicated
`characteristics.
`
`For each paying service, approximately every five
`minutes, a new service key K is generated in a random
`manner in the transmitter. Thus, during a session of a
`service (one or several hours) a few dozen service keys
`can follow one another. As soon as a transmitter gener-
`ates a new service key K it calculates for each subscrip-
`tion key Cgin operation for said service a message Mrby
`an algorithm in which the keys C5 act as parameters.
`Thus, for a sevice with the subscription scheme re-
`ferred to hereinbefore 22 different messages are in force
`at all times. The life of a message is equal to that of the
`service key K and for a given service there is the same
`number of messages as there are subscription keys being
`used at all times.
`
`
`
`The calculation of the messages Mgfrom the subscrip-
`tion keys Cfand key K takes place in the transmission
`' centre by means of circuit 20,. organized around a mi-
`taro-processor.
`
`Such a circuit is programmed so as to realize an algo-
`rithm using the subscription keys C,'(127 bits) and the
`service key K (56 bits) in the following way:
`(1) a confusion redundancy word 1r is formed which
`consists of 61 bits generated at random on each perfor-
`mance of the algorithm;
`
`6S
`
`0n the basis of the construction of M on transmission
`bits 1 to 61 of p. represent the word v. while bits 65 to
`125 represent the word tr. Obviously bits 62, 63, 64, 126
`and 127 must be zero. if they are not zero the word v is
`brought to zero before continuing the calculation.
`w and
`v are multiplied on the
`second field
`CG(251 — I), which brings about the disappearance of
`the confusion redundancy and one obtains K = v-rr mod-
`ulo (251-— l).
`A further probability test now takes place, because as
`K has 56 useful bits, bits 57, 58, 59, 60 and 61 must be
`
`PMC Exhibit 2200
`
`Apple v. PMC
`|PR2016-01520
`
`
`
`Page 8
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`PMC Exhibit 2200
`Apple v. PMC
`IPR2016-01520
`Page 8
`
`

`

`4,354,201
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`7
`zero. If this is not the case K is brought to zero before
`continuing the operatiOn.
`The 56 useful bits of K are then available in the form
`of 3 uneven octets.
`
`The jamming and unjamming of the video signal
`taking place respectively in circuits 22 and 52 can ad-
`vantageously be obtained by a process wherein the
`following operations are performed. The signal to be
`jammed is firstly sampled and then the samples are
`inserted in a video signal line. The :1 samples V0 to V”
`constituting are permutated in circular manner by
`(p+ 1) positions, so that the samples V(p+1) to Vn are
`placed before samples V0 to VP, the samples are then
`transmitted in this permutated order. On reception the
`samples of the jammed signal are again circularly per-
`mutated by (n—p) positions to restore the initial se-
`quence. The number n is determined line by line, ac-
`cording to a law which is fixed by the transmitter and is
`transmitted to the receivers.
`FIG. 2 shows the block diagram of a jamming circuit
`which can be used in the invention. The video signal to
`. be jammed is introduced by connection 50 into a sepa-
`rating circuit 51 which supplies a line synchronization
`pulse to a time base circuit 52 and the luminance and
`chrominance signals to a sampling circuit 53. In the time
`base circuit 52 the line synchronization pulses are used
`in conventional manner for generating timing signals H
`at the sampling frequency and line parity and imparity
`signals 2p and Empectively. The output of the sam-
`pling circuit 53 is connected in parallel to the signal
`inputs of two AND gates 54 and 55, whose outputs are
`respectively connected to two input circuits 56 and 57.
`The outputs of these circuits are respectively connected
`to the inputs of two delay circuits 58 and 59, respec-
`tively connected to the output circuits 6!] and 61. The
`outputs of circuits 60 and 61 are connected to the inputs
`of an OR gate 62, whose output is connected to the
`input of a smoothing circuit 63 joined to a circuit 64 in
`which a line synchronization pulse is inserted into the
`signal leaving 63.
`The coder of FIG. 2 also comprises a pseudo—random
`digital sequence generator 65 which can be a ten-stage
`shift register provided with nine re-looping points,
`whereby there is direct re-looping between last and first
`stage. The-eight intermediate loops are put into effec-
`tive operation when a level I is applied to the control
`input of the corresponding stage. These re-looping con»
`trol levels are applied from a loading register 66, which
`permanently contains an eight bit word. This word
`defines the configuration of the generator. For each
`field synchronization signal transmitted by the separat-
`ing circuit 51 and carried by a connection 67 to a regis-
`ter 68 which carries a ten bit word generator 65 is ini-
`tialized in accordance with this word, each stage assum-
`ing the state defined by the correSponding bit. For each
`field the same digital sequence of ten bits is generated
`with the tinting of the line synchronization pulses sup-
`plied by circuit 51 to generator 65. The eight bit word
`contained in register 66 and the ten bit word contained
`in register 68 together form the axis key to the jammed
`transmission.
`The output of generator 65 supplies a ten bit word to
`the initialization input of a counter 69, whose counting
`input receives the timing pulses H from the time base
`circuit 52. Counter 69 counts backwards on transmis-
`sion. When counter 69 is not at zero its signal output is
`at level 1, but as soon as it is at zero this output passes
`to 0.
`
`10
`
`15
`
`20
`
`25
`
`35
`
`45
`
`50
`
`55
`
`65
`
`
`
`3
`_The second input of gate 54 is connected to an output
`2}; of 52 in such a way that the uneven line signals trans-
`mitted by circuit 53 are transmitted to circuit 54. The
`second input of gate 55 is connected to the output 2p in
`such a way that the even line signals are transmitted to
`circuit 51.
`One control input of circuit 56 is connected to the
`output of an AND gate 70, whose first input is con-
`nected to the output A!) of 53 and whose second input is
`connected to the output of counter 69. The control
`input of circuit 5‘? is connected to the output of an AND
`gate 61, whose first input is connected to outputfiof 52
`and whose input is connected to the output of counter
`69-
`.
`The control input of circuit 60 is connected to the
`output 29 of 52, whilithe control input of circuit 61 is
`connected to output 2p of 52.
`Finally an input of circuit 64 is connected to an out-
`put of circuit 52 which supplies a synchronization signal
`S’, deduced from the incoming synchronization signal.
`The circuit of FIG. 2 functions as follows. During an
`uneven line signalfiis at the high level, gate 54 is open,
`circuit 60 is open towards gate 62, circuit 61 is closed
`and gate 55 is closed. In addition, gate 70 is closed,
`whilst gate 71 is open and the output of counter 69 is at
`high level. Thus, samples from an uneven line enter
`circuit 58 and jammed samples from the uneven line
`leave it.
`
`During the following even line signal 2;; is at high
`level, gate 51 is closed, circuit 60 is closed, circuit 61 is
`open and gate 55 is open. Moreover, gate 61 is closed
`whilst gate 6|] is open and output of 69 is at high level.
`The first samples are transmitted to the input of 58,
`whilst the last are moved towards the output of 53, the
`content of 58 remaining unchanged until the end of the
`even line. Finally there is an uneven line and the opera-
`tion described hereinbefore is repeated. Jamming of the
`even lines takes place in the same way with respect to
`circuit 59.
`It is clear that the circuit of FIG. 2 can be used on
`
`reception for restoring the initial forms of lines by using
`the same circuits 66 and 68, by connecting counter 60 in
`such a way that after its initialization at each line by 60
`it counts towards its maximum content instead ofcount-
`ing towards zero as was the case for the coder on trans-
`mission.
`
`the
`When the treated samples are in analog form,
`delay circuits 58 and 59 are advantageously load trans-
`fer circuits. When the processed samples are in the
`coded digital form these delay circuits are shift regis-
`ters.
`
`In the described embodiment the digital signal used
`by the pseudo-random sequence generator contains
`10+3=18 bits, but the key can be constituted by a word
`having more than 18 bits, e.g. 32 bits. The 14 other bits
`of the key make it possible to determine which conver-
`sion functions are active and which are not (2bits), what
`division of the resource is chosen, what relationship
`exists between the 10 bits of the shift register and certain
`parameters of the canversions of pure delays or circular
`displacement. In general terms the key can carry com-
`plementary information relating to the possible configu-
`rations of the signal. This is utilised for providing the
`possibility of replacing a single full definition sound and
`video programme by four independent low definition
`programmes, this result being obtained by dividing up
`the screen space into four quadrants receiving four
`independent pictures obtained by reduction by digital
`
`PMC Exhibit 2200
`
`Apple v. PMC
`|PR2016-01520
`
`
`
`Page 9
`
`
`PMC Exhibit 2200
`Apple v. PMC
`IPR2016-01520
`Page 9
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`

`

`
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`4,354,201
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`9
`means in the case of the Video and the sound channel
`into four narrow band sound channels. This possibility
`can be provided in the definition of the jamming system.
`The general public receivers are not necessarily pro-
`vided with these means which can be reserved for spe-
`cial users.
`
`10
`connected to the key calculation system 41. This con-
`trol circuit receives messages from the data extraction
`circuit 34, and supplies them to the key calculation
`circuit 41 after carrying out a possible shaping (e.g.
`parallel-series conversion).
`Two cases must be considered for the control circuit:
`
`The jamming of the picture sensitizes the latter to
`transmission faults and makes it necessary to provide
`redundancies. In the video standard adopted a time
`interval of 2.6 us is provided for this purpose. This
`interval remains free of any signal before jamming. This
`standard is shown in FIG. 3. Each video signal line has:
`a blanking interval Is which is not affected by the
`pseudo-random transformations or conversions, except
`with regard to the content of any digital signal which
`may be present, said interval containing the line syn»
`chronization and optionally a digital channel N for
`carrying sound.
`an interval Ircontaining the picture which is affected
`by the pseudo-random transformations or conversions
`and necessarily cntaining 15 us reserved for the chro-
`minance colour burst C (4.9 us) and to the jamming
`operations (interval B of 92.6 its), the latter margin may
`or may not be continuous and may be at the start or
`finish of lines, depending on the particular circum-
`stances.
`
`During the blanking of the field there is no transfor-
`mation of picture space in order to retain the possibility
`of broadcasting data in clear in a signal whose picture
`and sound are jammed.
`When the sound is carried by a digital channel using
`intervals 13 or by a digital channel using the insertion of
`supplementary signals into the chromiuance colour
`bursts it is sampled at one of the following frequencies
`which are compatible with the synchronizati