FR2467521A1 - DEVICES FOR RECORDING, RESTITUTION OR DECODING AND END-OF-PROGRAM DETECTION FOR VIDEODISK - Google Patents

Abstract

The invention relates to a video disc recording device for encoding an information word on a video signal. According to the invention, a means produces a video signal; means 49 produce a first data sequence corresponding to a start code; means 45 produce a second data sequence corresponding to an error code on at least part of the information word; and means modulates the video signal according to a recorded data word comprising the start code, the error code and the information word, the error code being a "coset" code on at least part of the data word. data recorded. The invention applies in particular to video discs. (CF DRAWING IN BOPI)

Description

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  of the vertical erase interval.

  In the known system, in order to decode this digital data recorded in the turntable, the line of the vertical erasing interval containing the data is admitted to a decoding circuit. After detecting the start bit, the decoder introduces each successive bit into a data register and checks the error code of

  group received looking for errors received, if any.

  A group error code, after decoding, has a particular error checking result (hereinafter called remainder), equal to zero when it starts from zero in the decoder, in

  assuming no error is detected.

  The data system described above can be interrupted by one of the many types of noise-induced errors. These errors include framing errors, where the received message is shifted one or more bits off its proper position, and error code faults, where the error code check indicates validity in the presence of 'errors hixtes by dubruit. It is important that the digital data read by the turntable is substantially free of undetected error. These errors

  caused by noise and certain other

  of the data system described above can be decreased by using the arrangement disclosed here for coding /

digital decoding of data.

  The arrangement for encoding digital data according to the present invention is to produce a start code at the beginning of each digital message, and an accompanying coset error code and information bits. Preferably, the error code and the information bits sequentially follow the start code. The implementation of the information bits at the end of the message is advantageous because it facilitates a simpler decoder in the device for rendering the video disc. A Barker sequence can be produced as a start code to improve auto-synchronization

and reduce framing errors.

  A "coset" error code is similar to a group error code except that either the remainder after decoding, or the contents of the remainder of the register before decoding, or both, are non-zero. In other words, the situation that is avoided by using a "coset" code is that where all zeros appear as

a valid message without error.

  The use of an error code with a non-zero remainder, according to the present invention, results in a lower rate of undetected errors than would be the case for a group code with zero remainder. This result is thought to be due to the particular nature of a video signal and the way digital information is recorded. The decoder searches for a digital message during the vertical erase interval where the transmitted lines are at the black level (logical zero)

  Meanwhile, logical zeros may be more likely

  only one of them. Therefore, noting that the remainder of zero is zero (after decoding), it is more likely that the noise will cause a zero remainder than any other non-zero remainder. For example, in the above described system, if there is a noise burst, equal to the start code and then a black level (only zeros), then this results in a zero remainder. The data system according to the invention, where the decoding method begins with a non-zero number and / or ends

  by a non-zero number is not subject to such errors.

  Various hardware configurations are available for decoding a digital message according to the above-mentioned format. The minimum requirements include data storage means for storing the received data, error code checking means including an error code checking register for calculating the remainder, means for detecting a start code, a means for detecting a valid remainder, and control means of the total decoding method. The present invention is also directed to the simplification and reduction of the equipment required for

decode the digital message.

  According to a feature of the invention, a recording device is provided, which records an error code so that at least a portion of the recorded digital data word has a verification result.

  error equal to the start code. According to another characteristic

  of the invention, there is provided a decoding device for rendering, which indicates that a received digital data word is valid if at least a part of the received data word has a verification result.

error equal to the start code.

  In one embodiment of the invention, the error code is arranged so that (1) the remainder after decoding a valid message is equal to the start code, and (2) this remainder is calculated on all the message, including

  the starting code. Therefore, the verification register

  error code starts with the start code and if no error is detected after receiving the complete message, it also ends with the start code in

the register.

  In operation, the successive bits of data are introduced into the code verification register

  error until a start code is detected.

  Then, the error code check register should not be emptied, but simply start calculating the rest starting with the start code. When the compet message is received, the same means to detect a

  start code is used to detect a valid remainder.

  The coding material used in the recording device

  videodisc record is arranged to receive the revealed decoder of rotaviderdisk without increasing

  substantially the recording material.

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  suoTslndImTp eTteA.Ae% u-T.e Tmead mun% uueuoo teoTlaes uemaoe; .jep pzBpuu4s a4sB:% euleuTaIt0ou; % UO.zuuQooel 01 UOTsTA9t9n ep enbTuqoeB ue szuej-qdmoo% uos Tnb xneD SeW [Bel.ue seBtudmT% e ssum sumu.z% selt eJuds (mnmTxem seusTt z'yV) teOTaeZB% uemao; e ep eteAJeBa.UT tul * 1 aJnST; andl years. eTnojua esnaelod-snos Bp enbTuqoel. el oeaB pzoooe ue: .aumoj, un-usXu; og. N eda. np UOTSTA97tq. ap Tuu2Ts unp s.aeT'-O: l .- 'ued stTul.gP seCa IVYNDIS fia lVyHoS LZS29t 7, start or start at 13 bits indicated by B (x), a redundant error checking code-at 13 bits indicated by C (x), and 51 bits of information indicated by I (x). The beginning of the next horizontal line is indicated by the next horizontal synchronization pulse 140a and the chrominance subcarrier synchronization component 142a. Thus, the individual bits of data are synchronous with the color subcarrier, and the total digital message is synchronous with the vertical sync pulse. It should be noted that the rate

  the pace of the data can be a multiple or a subset

  multiple of any subcarrier frequency. Likewise, other luminance values may be associated with logical one and zero, or more than one bit may be associated

at a given luminance level.

  A start code is used in the present system to synchronize the data system on the digital message to thereby avoid the need to detect the sidewall of the horizontal or vertical synchronization. Synchronization errors of a digital data system. in series result in framing errors, ie the data received is

  offset by one or more bits from its good

  position. Previously known systems for recording

  Recording of digital data on a coded videodisc signal showed that the sides of the synchronization signals were unreliable as a time reference and produced framing errors. The codes

  starting point proved to be more reliable.

  The specific start code chosen, 1111100110101 is one of the Barker codes known in radar and sonar technology. Reference can be made to R. H. Barker's "Group Synchronization of Binary Digital Systems," published in 1953 by Academic Press, New York, New York, United States of America. Barker codes are designed so that the auto-correlation function of a signal containing a Barker code that is off-line with itself, is

  maximum when there is coincidence and minimal otherwise.

  Indeed, if we assign a value of +1 or -1 to each bit in the start code and calculate the sum of the products of the respective bits for each offset position of the start code with respect to itself. similarly, this autocorrelation function will produce a net maximum when there is a coincidence. More particularly, a barker code shifted by any odd number of locations per

  ratio to itself produces an auto-correlation of 0.

  Barker code shifted by any even number of slots

  in relation to itself produces an auto-correlation of -1.

  However, when there is coincidence, auto-correlation

  is N, where N is the number of bits in the Barker code.

  In other words, a barker code shifted by any number of locations relative to itself differs by the maximum number of bit positions. In the presence of noise, this feature reduces the likelihood of false start code detection, in comparison

  to an arbitrary departure code.

  The information bits I (x) include a frame number (F), a band number (G), and spare information bits (A) for future expansion. The frame numbers identify each frame of the video signal

  by a unique 18-bit binary number. At the beginning of the video-

  disk, the first frame of the vid6o program is the "zero" frame. Then, each frame is numbered consecutively in ascending order. The band numbers refer to the video signal recorded in a group of adjacent turns of the band-shaped enspiral grooves. All the material in such a groove band is identified by a common tape number. As an example of the usefulness of the tape number, the video signal after the end of the video program material is recorded with a "sixty-three" tape number. Video turntable detects the sixty-three band as the end of the program

  and responds by raising the needle away from the disc.

  The error checking code C (xW) is calculated from I (x) in the videodisc recording device, to which I (x) is multiplied by a constant, H (x). is divided by another constant g (x) After this division, the remainder (the quotient is not used) is added to a third

  constant M (x). The result is C (x).

  In the siddodisk, the errors of the received message are verified by dividing the entire message, including the start code, by the constant g (x) above. If the remainder is equal to the start code, B (x), then the message is considered to be error-free. The constants H (x) and M (x) are chosen so that the remainder of the entire message is actually the start code. The constant g (x) is used in the videodisc recording device and in the videodisc, which is called the code generator polynomial. A specific value g (x) is chosen, which produces a code having particularly advantageous error detection properties for application to a videodisk medium. In the system described here, the addition operations. indicated multiplication and division are accomplished according to special rules for

  consider the equipment available to perform them.

  The error coding will be described in more detail below

  referring to the coding and decoding material.

  Figure 3 gives a block diagram of a videodisk encoder. A composite video signal from the source 30 is linearly combined in the adder 36 with a stream of data-to-digital bits 37 from the digital data generator 38. Synchronization means 32 provides color subcarrier and synchronization pulses. so that the data bits produced by the generator 38 are in synchronism with the color subcarrier appearing at the terminal 31a and so that the digital message is coded on the correct horizontal line in the vertical erase interval. The bits of information, appearing in the above-mentioned context, are found in the above-mentioned section of the eighth report. np euenbgsqns eTal. oi '(elTou.uemeaLe2) e: ul..suoo eaoueuTunl I aU2Tl eun S% se 8L, 1. wateruop eu2 'e: - eB auanb! sqns 81, aU2-F' e Ts

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say again. -

  The microprocessor 10, by the buffer 16, controls the extraction of the line 17 '(or line 280') out of the video signal. The first digital message is obtained by continually searching for a start code in the video signal. Then, the buffer memory 16 is closed. Then, based on the timing of the arrival of the first digital message, the buffer opens about six lines before the time when the next digital message is expected. If no valid message is found, the information buffer 16 is

  closed about six lines after this expected time of arrival.

  If a valid digital message is found, memory 16 is closed and a new arrival time of the next digital message is calculated based on the time of arrival of the current digital message. In this way, the microprocessor opens a gate or 'data window', about twelve lines wide and centered on the expected data.The time interval between the center of a data window and the next is roughly The width of the data window is chosen so that in the worst case of the time conditions, the expected data is in the data window. time, as will be explained below are: limited resolution of the digital timer, rate of slip of the timer, uncertainty of the program to determine the moment of arrival of the present data, and time differences between the even frames The use of another microprocessor and / or timer can be made possible by adjusting the width of the data window accordingly. The logic of finding the data and centering the data window will be described below in

referring to Figures 10 and 11.

  The microprocessor 10 is also responsive to the controls 14 on the turntable panel (charge, pause

  and exploration) to control the mechanism 12 of the rotator

  disc and cause the display 22 of the turntable to

  a predetermined program, as will be described hereinafter.

  The turntable mechanism is further provided with at least one needle "jumper" that can be controlled by

  the microprocessor 10. A jumper is a means,

  electrical, electromagnetic or other, for impulsively moving the reader or signal sensor means yers adjacent grooves or tracks on the support of the videodisk. The use of the jumper to suppress the condition of blocked furrows will be described below in

  referring to the flow charts of Figures 10 and 11.

ERROR CODE

  As mentioned above, the videodisc recording device uses the I (x) bits to calculate C (x). Because of the large number of potential combinations (I (x) and C (x) together are 64 bits long) and the desire to determine the error detection and correction characteristics of a given code without resorting to the enumeration, the error codes are treated mathematically. A general mathematical development of the theory of rings and Galois fields GF (2m), applying to error codes in general, can be found in W. Wesley Peterson's "Error Correcting Codes" published by MIT Press. , Cambridge, Massachusetts, United States of America. In this case, the error coding in the videodisc will be better understood in terms

some simple definitions.

  A digital message, including ones and zeros, can be considered to represent a polynomial

  algebraic including powers of x. The coefficients

  The respective powers of x are the individual bits of the message. For example, the 4-bit message 1011 may be represented by the polynomial P (x), where P (x) = 1.x3 + 0.x2 + 1.x + 1.x0 = x3 + x + 1 By applying this notation to the start code, 1111100110101 we have -B (x) * 12 Il 10 8 5 4.2 B (x) x = l2 + x + xl + x + x + x + 4 x2 + 1 The highest power of x is called the degree of the polynomial. In the example above, B (x) is a

polynomial of degree 12.

  Polynomials can be added, subtracted, multiplied and divided using the ordinary rules of algebra except for the expression of coefficients in terms of modulo 2. An abbreviated notation for the remainder of a polynomial after division by another polynomial is indicated by square brackets. Indeed, if = Q (x) + t3 where the rest, r (x) has a degree lower than the divisor, g (x), we have [P (x)] = r (x)

  In the video recording device

  disk, the total message recorded on the videodisk is represented by a polynomial T (x). In Figure 2 we have T (x) = B (x) x64 + C (x) x51 + I (x) (1) The term x64 shifts B (x) by 64 bits, because B (x) is the beginning of the data format. Similarly, the term x51 shifts C (x) by 51 bits to represent that C (x) is recorded before I (x). According to the device described, the recording device calculates a value for C (x) so that the total message, T (x) has a remainder equal to B (x) after being divided by g (x). Indeed, assuming that b (x) has the form C (x) = [I (x) .H (x)] + M (x), (2) then H (x) and M (x) are constant polynomials chosen so that [T (x)] = B (x) (3) We can show that the equations (1), (2) and (3), when they are solved with respect to the constant polynomials H (x ) and M (x), give H (x) = t x1273 M (x) = tB (x) x13 + B (x) x1271 Figure 7 contains a table listing the values chosen for B (x) and g (x ), as well as the derived values for H (x) and M (x). It should be noted that the table of FIG. 7 shows the higher order bits to the right, so that they are in the same order as the latching storage elements appearing in the diagram.

logic of the same figure.

  In the turntable, the digital message

  recorded is read by the electronic circuit of the

  disk. The data recorded on the videodisk is T (x).

  The data read by the turntable is R (x). If there is no error between the recording and the restitution, we have T (x) = R (x). The errors in the received message, R (x), are checked by dividing R (x) by g (x). If the remainder is equal to B (x), the start code, then the message is considered to be error-free. Moreover, if

  remainder does not equal B (x), so this indicates an error.

  The characteristics of a code produced in the above way depend on the choice of g (x), called the generator polynomial. g (x) particular chosen for the support of the videodisk is one of the codes produced by the calculator, demonstrated by Tadao Kasami in "Optimum Shortened Cyclic Codes for Burst Error Correction", published in IEEE Transactions on Information Theory 1963. A mistake of Chrominance synchronization subcarrier composase in a digital system is a type of error where adjacent bits in the digital message are lost. Chrominance sync subcarrier errors are considered to be a probable type of transmission error in the videodisk medium. As shown by Kasami in the above reference, code that can correct simple chrominance sync subcarrier errors of 6 bits or less, can be implemented using a generator polynomial given by g (x ) = x13 + x12 + x + x10 + x7 + X + x5 + x 4 + x 2 + 1

  Moreover, we can see that for g (x) given

  above, any chrominance sync subcarrier errors of 13 bits or less will be detected, and that 99.988% of all these errors plus

  long as 13 bits will also be detected. The turn

  videodisk, as described here, only uses

  error detection capabilities of the chosen code.

  As a specific example of producing the error code, consider the case where the frame number is 25,000, the band number and 17 and the reserve bits are 0. As 25,000 in binary representation is 000 110 000 110 101 000, and that 17 in binary representation is 010 001 (the higher-order bits are on the left), the 51 information bits are 000 000 000 000 000 000 000 000 000 110 000 110 101 000 010 001. L transmission order is the following reserve bits first, then frame number and then band number, where the most important bit is transmitted first. The error code for I (x) specific above, calculated as the remainder of I (x) by H (x) plus M (x) is represented by 0111100100010 / The next video frame is 25.001 or 000 110 000 110 101 001 in binary representation. For the corresponding bits of information, 000 000 000 000 000 000 000 000 000 110 000 110 101 001 010 001, the correct error code is 1000101101110. The complete digital message for the frame 25.001 including the starting code is by therefore 1111100110101 1000101101110 000 000 000

  000 000 000 000 000 000 110 000 110 101 001 010 001, in-

  The first 13 bits form the start code, the next 13 bits form the code

  error and the 51 bits of information come last.

  In the above videodisk, the errors are verified in the above numeric message by dividing the received message by g (x). If no error is detected, the rest is 1111100110101, which is exactly the

start code.

EQUIPMENT

  Figure 5 gives a block diagram of a means for producing T (x). Under the control of the control means 50 of the transmitter, 24 bits of information are introduced by the data bus bar 39, and 27 bits of information in reserve are introduced by the data bus bar 39a into a shift register 44 at 51 bits. . I (x), which includes these 51 bits, is then shifted into another

  52-bit shift register 52.

  At the same time, during the 51 pulses of

  offset, an encoder 45 calculates C (x) in the following manner.

  A means 46 for dividing and multiplying polynomials is sensitive to the serial transmission of the 51 bits of I (x)

  to calculate the remainder of I (x) by H (x) divided by g (x).

  M (x) is then added in parallel in the polynomial adder 48. The resulting code C (x) is introduced into the 13-bit shift register 54 and B (x), the start code, is introduced by the busbar 49 in another 47 to 13 bit shift register. Since the start code is a constant numeric value, this introduction is preferably accomplished by fixed connections to the parallel inputs of the shift register 47, to oppose a software implementation. In positive logic notation, the corresponding parallel inputs of the register 47 are connected to the potential of the mass each time the start code has a zero, and to a number of digits in the same time. '(Z a OL6'9'g'Z'0% tq ap uoTTsod) I. xne9 xnap sno%% uos (x) 2% a (x) H pueno' -uamoATIoodsai gc 69% a 99 '9 -' Fsnloxa O1 a% 4od el apaira aui aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aIcno! ad ua 'ZL% OD safsl32eaJ sap nueuoo np% uelInsgz. Tnpoid el zuúelsnos ue 4a '(x) g aed Oç op eT4aos el% IueTldFl3nm ua elIdmoooe% se (x) S aed (x) I ap UOTST.Tp em * uamaAoadsa' A8 to 8 'L08 the snTIoxa no a% 4od e9gaua eun eg eTla 4se (x) i a9.xul (8% a ú 'I% Tq p uoTITsod) I i9s% sa' (x) 2 sed -sTem (x) H ap% iuaToTjajoo a, nb sToj anbeto B '* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * AouessTnd 8p samuae sap seuaso $; aoo sap) uoloewsnos the% a uo% .Tppe, I enb eaeajou uo 'samou & lod oz sep uolslaTp el $ a uoTloTtdTnu el anod earnST; 9% oTldmfls and the aOdidS inodOntOtO silI. ap I9u92% uama s a hnod asuuouame snssap - o uosaa% & j Sp aOueJagi $ ei Sp [7L-LOI seSed 'L oatIdmqo nu ajaoaJ as% nad uo' asaj np a! stoa np Zk0 - 00 saGaos L s81 suep nuaqueUm jsa aesa eal 'saçnsu: *' aeTs ua% uaemu -Wti> nmTs saTldmoooe% aos (x) '. uoTsVip el% a (x) H zed uoTIBOTIdT'1nm el' osa np a-SIstBaa a% u "uomo $% [q O elqaos ep seujoq sep% tueLe sasolioqp pueummoo - solJ -dtii no salnoseq se (- (aainSn el anis ç) inepoo np enb 0o -ITJTo9ds uoTsTle.i Spomun au auop L. canSj el

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  % Ss nbTx9gmnnu e2esseur el onb ua; ssme% ap aouaga5aJ aun og-a puemmoo op ua.om nee znaeonpuo9 does olPTA uOtOuSaTUOatOuS uOttOtSIndmt aun - * cn anaonpooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo Ein bone nod '& L '94' Z5 sasISea.sToal. sal suep nusauoo '(x) to lIuol. ae2ssam eI apuemmoo o apuemmoo ap uaúom al * a maedgp ap apoo aI, anb sTo; anbeqo q $% TI.Tsod elSTuaod 9L Iz Zgt3 exclusive 81, 84, 85, 88 and 90, respectively. After 51 clock pulses, one for each bit of I (x), the contents of the registers Q0 to Q12 are the remainder of I (x) .H (x)

after division by g (x) .-

  Note how M (x) is added to the contents of the remainder register. The addition of the coefficients is in modulo 2 arithmetic performed as the exclusive OR function. Whenever M (x) has coefficients of +1, the output complement U of the corresponding flip-flop is used; whenever M (x) has coefficients of 0, the output Q is used. Figure 6 shows a block diagram of a means for decoding the received message, R (x), and it is a mode of

  realization of the memory 16 of FIG.

  above. The control signal to the driver 71, forming an input, conditions the decoder of the receiver of FIG. 6 either to receive the data of the video signal or

  transfer the data to the microprocessor.

  At the receiving state, each bit is simultaneously

  introduced in two separate registers. One of these

  very, 60, is for the data and the other, 62, is for checking the error. Register 62 is a polynomial divider. However, when acquiring new data, the feedback path of the divider is inhibited so it functions as a right shift register. The operation of the register 62 will be described subsequently in more detail with reference to FIG. 8. For the moment, the register 62 is sensitive to the means of controlling the receiver 64 to receive successive bits of R (x) or to divide bits successive of R (x) by g (x). In each case, the contents of the register 62 are available at the bus bar 78 and is applied to the detector

  66 of start code and valid data.

  The receive operation starts with the register

  62 conditioned to function as a register to -

  offset. After detection of B (x) by the detector 66, the control means 64 conditions the register 62 to function as a polynomial divider. Thus, the division of the polynomial by g (x) begins with B (x) in the divider 62. The control means of the receiver 64 is further sensitive to the detection of B (x) to trigger a period equal to the remaining bits After the triggering period, the divider 62 contains the remainder of R (x) modulo g (x), which must be B (x) if the message is valid. In the error, the register 60 has shifted data bits At the end of the triggering period, the register 60 stores only the last 24 bits, but since the 24 information bits are placed at the end of the message, the register 60 contains the assigned information bits.

  the reserve information bits, additional stages

  offset register can be added.

  The interpretation of the output state signal to the driver 75 depends on the state of the control signal to the driver 71. When the control signal to the driver 71 conditions the receiver to acquire data (reception status), the signal of state to driver 75 is

  defined as "received message". When the command signal-

  to the driver 71 conditions the receiver to transfer the data (transfer status), the driver 75 of the status signal indicates "valid data". The driver control signal 71 also restores the control means of the receiver 64 and applies the results of the verification

  moreover, at the condition signal to the driver 75.

  The received information is transferred from the shift register 60 in response to external clock signals from the microprocessor to the driver 73. After the data has been retrieved, the command signal to the driver 71 can be reset to its previous condition. the receiver-decoder for

  continually search for another start code.

  Figure 8 shows a logic diagram, partially

  FIG. 6. The latches having output terminals Q to Q12 form a register of the remainder. The division of the polynomial by g (x) is accomplished by multiplying successive terms at the output of QI2 by g (x) and subtracting the product (by the exclusive OR gates 100 to 108) from the contents of the remainder register. A feedback connection of Q12 (through the NOR gate 109) is made to an exclusive OR gate each time g (x) has coefficients of 1, except for bit 13. As the coefficients of g (x) are I for the bit positions 0.2, 4, 5, 6, 7, 10, 11, 0, 12, an exclusive OR gate is placed at the data input of each respective latch of the register of the rest as shown. The NAND gate 118 detects B (x), which is both the start code and the valid error checking code. The receiver control counter 117 starts counting in response to a start signal from the AND gate 120, it counts 63 clock periods, and applies a stop signal used by the NAND gate 111 to stop the clock. to all other flip-flops of the decoder. FIG. 9 shows an embodiment of the receiver control counter 117 comprising 7 flip-flops

at 136.

  The sequence of operations for receiving data is as follows. When the control signal to the driver 71 is in the high state, the data is applied to the divider 62 by the AND gate 110o The flip-flop 119 has been

  previously established, which inhibits the counter signals

  reaction in the divider 62 by blocking the NOR gate 109. The register 62 then functions as a shift register. Upon detection of B (x), the output of the NAND gate 118 goes low and the Q output of the flip-flop 119 goes down one clock period later. Therefore, the feedback is validated for the division of the polynomial by the output of the AND gate 120 by means of the NOR gate 109 when B (x) is detected in the remainder register. After 63 clock periods, the counter 117 stops and the status signal to the driver goes high, indicating "received message". The shift register 60 holds the last 24 bits of I (x). To transfer the data, the control signal to the driver 71 goes low. The inverted output of the NAND gate 118, which is low if the remainder after division is B (x), is connected to the state signal to the conductor 75. External clock pulses to the conductor 73 cause successive offsets of given in the register 60 to the output data signal to the driver 74. The external clock pulses also empty the register of the remainder by introduction

of zeros.

  The above arrangement shows a register of

  remains beginner and ending with the same constant

  nothing. However, it will be understood that other arrangements are possible. For example, after detecting B (x), the remainder register can be set to a first arbitrary constant. So after division, the register

  the rest is checked for a second appropriate constant.

  The first constant, or-the second constant, can be

  zero; the two constants may not be zero.

  The simplified material resulting from the error code format described here will be observed. Ending with the start code, B (x), as remaining valid, the start code detector (NAND gate 118) also serves as a valid code detector. By starting the division by the start code in the divisor, a control step is eliminated since one does not have to empty the register

rest.

  Typically, error codes are placed at the end of a message. However, by placing the error code before the information bits, the receiver controller is further simplified because it does not have to distinguish the bit information bits from the error code in that

  which relates to the data storage register 60.

  In addition, the receiver controller, as can be seen in FIG. 8, is a simple counter 117, having a start terminal, a stop terminal and producing a

  trigger for a single time interval.

IMPLEMENTATION OF THE MICROPROCESSOR

  The digital information, including the band number and the frame number, is. recorded on the video signal and is used by the turntable for

  obtain a wide variety of features. The infor-

  the tape number is used for the record player

  to detect the end of the refund (sixty-six

  three). The information of the frame number in ascending order

  is used to calculate and display the

  the program on the light-emitting diode display means 22 in FIG. 4. If the length of the program material is known, the frame number information can be used to calculate the remaining time of restitution of the program material. program. For NTSC type signals, the elapsed time of the program in minutes can be obtained by calculating the frame number divided by 3,600. If desired, the duration of the remaining program can be derived from the previous calculation. This feature is useful for the viewer when he or she searches for a desired point in the program. A particularly useful feature, derived from the information of the frame number or the number of frames, and the correction of the blocked groove which will be described hereinafter with reference to the more general case, the

  error correction of course of the needle.

  The numbers or field numbers represent a real position of the needle. Thus, each time the needle enters a groove again, whether after skipping tracks or after operation of the scanning mechanism, the actual position of the needle can be determined from the first valid number of frame that is read. Both the run or run error correction system and the program play time display means use the number or frame number data and therefore share the decoding part of the video data system of the video disc. The particular path error correction system described hereinafter uses the number data or number of frames (needle position) to hold the needle on or ahead of its expected position assuming a predetermined relative speed needle. /disk. The display of the playback time of the program uses the data of the number or

  frame number for an indication of the restitution time

  tion, which is actually another representation of the

position of the needle.

  The microprocessor controller has several internal modes. Fig. 10 is a state transition diagram indicating the mode logic accomplished by the microprocessor program. Each of the circles represents a mode of the machine: load, spinning

  acquisition, restitution, pause, pause locked and end.

  For each mode, the needle position and display status are indicated within each respective circle. The arrows between the modes indicate the logical combination of the signals, applied by the controls (load, pause, scan) of the panel, which cause a transition from one mode to another. The charge signal indicates that the turntable is in a condition to receive a video disc. The pause signal is derived from a corresponding switch on the control panel, and the scan signal indicates

  the operation of the exploration mechanism.

  After turning on the power, the system goes into CHARGE mode. A videodisc can be placed or loaded on the deck in this mode. After loading, the turntable enters TOURNAMENT mode for several seconds, which allows the turntable to be brought to its full speed of 450 rpm. At the end of the mode

  of TOURNAMENT, is introduced the mode of ACQUISITION.

  In the ACQUISITION mode, the digital subsystem lowers the needle and continually searches for "good reading". In ACQUISITION mode, a "good reading" is defined as a valid start code and a valid error check remainder. After finding a "good reading", the system goes into

RETURN.

  In RESTITUTION mode, the microprocessor establishes in the memory an expected or expected future frame number. The predictable frame number is increased or reset at each frame. For all subsequent reads, the microprocessor uses the planned frame number to perform two additional checks to further improve the integrity of the frame.

the data.

  The first additional check is a sector check. The videodisk in the present embodiment contains eight frames at each turn, dividing the disc into eight sectors. As the relative physical position of the sectors is fixed, the sectors follow a recurring periodic order while the disc rotates, even if the needle jumps over a certain number of grooves. Although the digital information can not be read during one or more frames while the needle jumps to a new groove, the microprocessor maintains the time and incrementally increases the expected frame number accordingly. When the needle settles in a new path and picks up a new digital message, the new frame number is checked against the expected number. If the sector is false, the data is considered a

"bad reading".

  The frame number is represented by an 18-bit binary number. The sector information can be obtained from the frame number by finding the remainder after dividing the frame number by 8. However, it should be noted that the 3 least significant bits of a binary number are in modulo eight. Therefore, the 3 least significant bits of each new frame number must be equal to the number of frames in the field. eun: uenboAold 'SlInoUUa / AslV ep e elnee & n ew eq uaqTl esed uonoq np uoTssaid ú sheAnou in the N umberTM Ia e TnpoA4uT% sae M-IfoU0SA iSnvd ap epom el', aqTl se ssd ep uonoq el pueno eanbsTp el ans ea leTpea sitoTe UOTTSOd BS e nuuaeum% sa ae enbsTp np uToI do not know how to do it, but do not know how to do it, but do not know how to do it, but do not know how to do it, but do not know how to do it. %% seanoeaI sesmeAnem sap e% 4moo. ea uaTq no eancoeaL auAUQn au gauuop eaap seuE ssn-el xnap sep aunil NOISDIISSL U p ap ne neiSiRoDVP apom np aess Sz unip sjol enb ezu2gs leaD * eazToal sajt4oeol uesTAnum ep eidmoo el ITlqeB $ 9 inassaoodoooTm eI 'eTO hI SG ep epom ne NOIjISIODVoP apom np esssed uo pueno NOIIgIflODV P ep el el anod uoTTsuel. aun tueeWeI29 enboAoad 0oz 01 earnST_ -el ns 9, asniç% 1se eTeo ammoo'sepom suTsaeo suep uoTejoTldxeap IBu2ws unp eouaspad el 'NOILISIDlOVyP epom el puaedai emas. s ea 'seAT% 1nogsuoo seairoat sesTeAnem ezuTnb sady * amea% and op na9Jd o9agmnu and thodoductualinoditatesto% uos% a seaunoel 5 seawpTsuoO% u * s sanoeI seane sal senol "ean4o and esTAnemu euneamo apoo p suoo sa aeluasgaJd aguuop eI saose 'sTolI- [s 9 ap eqeldaeooe amume and e a.naTçadns% sa eouaJ9j: p eI TS * n9.ad oagmnu np uolrTs ap nothing-oe oagmnu 7I and-aTqsnos anassaooadoioym aq -amerea% ap oo oigmnu np squBodmy snnd sa- sq L ss ss ss s ss s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s t s uogea np 3uot aI a-itTnSis ep% uamasAnom np mnmTxem 5 anpuae, i [ep% its% 'enpua, 9, p uoTkeoTr; TJA' and is also 9% TJ29% .uTI ap UQT% .oTTJA epuooaes to Unnel .oas np uoTieo-_TiagA and.assed anod n.aad amure% ep oagmnu np suueaodumT supom set siTq xne xne29 LZSú9tz

  RESTITUTION when the sixty-six band

  three. Figure 11 shows a flowchart of the program

  executed by the microprocessor. The material of the micro-

  processor includes an interrupt line and a

* programmable timer. A commercial microprocessor

  for the present system is the Fairchild model

Semiconductor F8.

  The microprocessor uses the timer to control the window during the time when the information buffer searches for the data. This "data window" has about twelve horizontal lines wide and is centered on the expected data. When no data

  is found, the timer maintains synchronization

  internal program at a time interval of

the frame.

  The interruption of the microprocessor is applied to the state signal to the conductor 75 (FIG. 4). The

  interrupts are validated only in ACQUISI-

  TION, when the system continually searches for data. The program is interrupted when a digital message is received. The interrupt service routine (not shown) establishes an interrupt flag signal

  if checking the error code indicates the validity.

  Then, in RESTITUTION mode, the programmable timer is used to indicate the estimated time of

  the arrival of the next digital message.

  The switching inputs (charge, scan, and pause) are conditioned to prevent rebound of the switch from causing unwanted response of the turntable. The microprocessor program has a logic circuit to suppress the bounce or to stabilize the switching inputs. Stable switching values are stored in the memory. An account

  separation is maintained for each switching

  tor. To verify the stabilization 154, the switches are sampled and compared to the stored switching value. If the sampled state and the stored state are the same, the stabilization count for this switch is set to zero. Switch states are sampled as often as possible. Each frame (every 16 milliseconds for NTSC), all stabilization counts are incremented

  unconditionally. If the resulting account of

  If the value is greater than or equal to 2, the memorized state is reset to the new (stabilized) value. We act

  then on the new state of the switch.

  The first programmed step (FIG. 11) after application of the current is the initialization or initiation 150 of all the parameters of the program. The timer is set to trigger a video frame. Mode is established

at CHARGE.

  The next step 152 is a program to perform the state transition logic shown in Fig. 10. The stabilization counts are normally incrementally increased at this time, and examined to determine if a new switch state

is totally stabilized.

  After the mode selection logic 152, the -

  program enters a tight loop 153 to (1) sample the switch adjustment stabilization counters to zero, if necessary, at 154 and (2) verify that the timer is closed to trip

  in 155, and (3) check whether the flag signal of interrup-

was established in 156.

  If the interrupt flag signal is set to 156, the program transfers the data, 157a, from the information buffer and sets the timer,

  157b, to trigger a new image interval.

  When the interrupt service routine sets the interrupt flag signal, the contents of the timer are stored. The program then uses the previously stored contents of the timer to set the timer, 157b, with a corrected value predicting the approximate time of the presence of the next digital message. As previously noted, even if the data represents the first good reading in ACQUISITION mode, the count of bad readings is set at 157c to thirteen. If the interrupt flag signal is not set, the program branches out because the timer closes to trigger, at 155. If the machine is not in RESET mode, at 159, then the timer is set to triggering another frame interval, at 158. If the machine is in RESTITUTION mode, at 159, then a number of critical tasks 160 are performed. The data window is open, 160a (setting the control signal to the driver 71 of Figures 1 and 8 to a logical one) about six horizontal lines before the expected data. The received data is read and verified as previously described. After receiving the data, or if no data is received, the data window is closed. The timer content, which represents the current time of arrival of the digital message, is used as a correction factor to reset the timer, 160b. The timer is therefore set to center the next data window for the expected time of arrival of the next digital message based on the current time of

  the arrival of the digital message present.

  The expected frame number is reset at 160c, the band number is checked in search of the start (band 0) and the end of playback (band sixty-three), 160d and the count of bad readers is increased in increments of 160Z, for a bad reading. For valid frame data in the program display material, the time is calculated and displayed, 160f. If the valid frame data indicates that the needle has jumped backward, the needle hopper means is turned on, 160th, and the ACQUISITION mode is entered. Similarly, if the count of bad readings reaches 15, the mode of ACQUISITION is directly introduced, 160h. During all the time used for the criticized tasks 160, the switch stabilization check routine is periodically repeated so that the switches are checked as well.

  as often as possible. The program returns unconditionally

  by the mode selection logic 152 to the close loop 153 and expects the timer 155 or interrupt check 156 to indicate

  the arrival of the next digital message.

  The timer can be set by loading it directly with programmed instructions. However, rather than using a sequence of instructions, it is better to "set" the timer by setting a location in the memory (a mark) that corresponds to a trigger condition of the timer. The timer is then autonomous. Triggering, or closing for triggering, is detected by comparing the contents of the timer with the mark set in the memory. The next desired trigger condition is established by adding the interval of

  next desired time to the previous content of the temporisa-

  and memorizing the result in the memory. The timer is thus "set" whenever valid data is received, or if no data is received in the data window, by setting a new mark in the memory, corresponding to the condition

following trigger.

  The programmable timer in the micro-

  processor used in the arrangement described, is condi-

  program to divide the entrance cycles

  1.53 MHz clock by a factor of 200. The temporisa-

  For example, it counts once for 200 clock cycles at 1.53 MHz. A vertical frame (1/60 second for the NTSC standard) then represents about 128 timer counts. Alternatively, a timer with a multiple other than 1.53 MHz or a timer using a timing source can be used.

independent of the video signal.

  The data window is large enough to

  allow multiple sources of timing errors.

  The uncertainty of the timer due to the limited resolution of this timer is equal to one least significant bit, which corresponds to two horizontal lines. An accumulated slip error because the 128 timer counts do not exactly represent a vertical frame, is somewhat less than a line after

  16 consecutive frames where there is no valid message.

  Note that since the 1.53 MHz color subcarrier clock is an odd multiple of half the line frequency, a timer that counts a multiple cc "responding to the color subcarrier clock

  will have a zero slip rate. In the particular arrangement

  Link described here, the uncertainty of the program to determine the time of arrival of the data, is of the order of 97 microseconds, or about 1, 5 lines. Finally, since the frames are interleaved by one out of two, the time of a next digital message is either 262 lines or 263 lines, depending on whether the current frame is even or odd. Although the program can keep track of odd and even fields, it is easier to simply expand the data window of an additional line. By combining the above factors, it can be seen that a data window spanning three timer counts (approximately 6 rows) both before and after the start of the expected data is appropriate to allow the worst conditions of delay.

ERROR CORRECTION FROM

ROUTE NEEDLE OR TRACK

  As mentioned previously, the frame number information can be used to detect blocked furrows. If the new frame number (after verifying the sector and the range) is smaller than the expected frame number, then the needle has jumped backwards and repeats the path of one or more previously restored turns, that is, to say that a blocked furrow has been encountered. If the new frame number is greater than the expected frame number, the needle has jumped

  forward, that is towards the center of the disc.

  In this application, skipped furrows are ignored; if the new frame number is higher (but still passes the sector and span check) then,

  the expected frame is reset to the new frame.

  In some other applications, for example when the video disc is used to record digital information on several horizontal lines, it may be necessary to detect and correct the skipped furrows as well. However, in this case, a blocked groove is corrected by operating a "needle jumper"

  until the needle is returned to the desired track.

  Possibly, the needle will be advanced beyond the

blocked groove fault.

  In a more general sense, the use of the frame number information according to the present invention provides a precise means for detecting general route errors. In any video disc system with spiral or circular tracks, with optical systems and without grooves, errors of course due to defects and contaminants are always possible. The present system provides a means for detecting and correcting such errors in a videodisc. For a positive path, bidirectional jumper means is provided to move the reader backwards or forwards in the program material. So, when-a path error is detected, whether it's a skipped track or a blocked track, the drive is moved in such a direction

  that it corrects the error of course. Although the assertion

  If the reader or sensor can be used for route error correction purposes, a jumper may be used. e uppo 5 saeqqoeBgp uou sineaLap sTA - sT * p9iTano9s e1 'sinooaad ep inaaeagp uoToeaoo op enbTaunu ems s al sue [ssrnoo.ed ap selqudaooeuT sineaje sap JanboAoid% uemealne% ueAnod'sueuTmeuoo no snej9p sap uaTuoo enbsTpo0pTA el Ts amgm Tssngal 0O sanooad a zTueaqo% ned uo 'sg9adoJadde apuemmoo ap anbg2ol aun% lnalnes a: uSe nn teb ua nd uo seo sal sno. suea * anpua %% e as a la ignaloal aBl jBuauea ap anb 9gntd 'aintoai apuooas aun i.zaua ap% a zaedap ep% utod nd analoel el aeuaema ap eIqeTqnos ae.%% ned 5Z IT' (anbsTpoppTA np ^% oddns ala agsTioz9m nbTUagmnu aguuop aunp uoTfr4TsaJ aBIdmaxa ad) suoTIoTIdd sauae.aeo anoj -enlnoA aBsTd ml e aegueuae% os ellTnSTel enb eo minbsn -uosTndmT i ed saestd ap 9uuop aJqmou one year 9ouldD p% se JBnaoel aB 'sanooaed ap aB9oaegp OZ aneaaeil p inepueJ2 mI e IeuuoTaodoad irea9 suoTslndmT September Jaqmou al 'suoTsIlndmTp ETAAS aun asuodgia ue puemmoo BAJ% ned neanus a no esanooaed ap eiloeBgp JneaLIl ap B napief el leuuoTlodo0d elITTtTeil Bp% uemaAnom a iuesTnpoid ue eBoeaoo is eI 1% uemeIoaTp 51 9ueumea aq% Inad aJn4oae tcpSsodsTp alsqqdsssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss Ol 9IgAaJ TTsodsTp el oA ae JesTITn f 9Tjadoadde jnaBnes unp enbTsTogds sdduaxe uo 'sanooaed ep saneaLae sap az2Taoo inod aJTesseogu topTdua Bsuod9a ae 94dmpm.! uem -QaaTtfljno.Tijd snld aBJ qnad' sJUnallTu aided aids in a sanooaed ep saednLzq saneJae sep q aepuodga nod 5 senbTsTJa9% oeauo sauuoq salt aToAe sed eu% nad% e 'leugTs np teJeTds ue as aD opaBle sanooaed a 9% adpa uemae-ieaug92% s JaTint29a% uemGssTabasse, to * auqua99jad% ee ineoel np aeod ue esTmai ap uaXom no 9aedgs LZas9tZ the probability of an undetected error reading at

a negligible level.

  For a rough approximation, we can estimate

  the probability that a statistical numeric entry

  raises the data system as a valid message containing a non-sequential frame number, thereby to actuate the needle jumper. The probability

  statistics of a good start code is I on 213.

  The statistical probability of a good error code is also 1 in 213. The statistical probability of a good frame number is calculated as follows. The frame numbers contain 18 bits. Since there are 8 sectors on the disk of the considered system, the 3 least significant bits of each frame number indicate the sector number, which must correspond to the expected sector number. The remaining 15 bits, which represent the groove number, can vary over the permissible range (63 furrows). Therefore, only 126 of the 218 frame rate numbers will pass the sector and span checks. By combining all the security features, the probability of an undetected error is 126 out of 244.

  The above estimate is based on the assumption

  of a truly statistical entry, without

  account of several factors further reducing the probability of

an undetected error.

  For example, on a videodisk track, the noise of the chrominance sync subcarrier where the erroneous bits are adjacent to one another is more likely than other types of noises. As previously noted, the particular error code chosen detects all chrominance subcarrier synchronization component errors of up to 13 bits, and also the high percentage of all the subcarrier synchronization components of the subcarrier synchronization component.

  longer chrominance. Likewise, as we have

  explained, the choice of a non-zero remainder for the code, error checking further reduces the probability of an undetected error. In addition, the particular departure code chosen, a Barker code, reduces the probability that a noise may cause the detection of a false start code. The revealed data system, applied to the videodisk system, results in a relatively low undetected error rate and the false alarms, which may otherwise cause unnecessary needle movement, are considerably reduced. The data security obtained by the revealed system improves the stability of many functions of the turntable, such as the display of the program playback time, which depend on the digital data recorded for a given time.

good operation.

  Of course, the invention is not limited to the embodiment described and shown which has been given by way of example. In particular, it includes all the means constituting technical equivalents of the means described and their combinations if they are executed according to its spirit and implemented in

  the framework of protection as claimed.

Claims (17)

  A video disc recording device for encoding an information word on a video signal, characterized by: means (30) for producing a video signal; means (49) for producing a first data sequence corresponding to a start code; means (45) for producing a second data sequence corresponding to an error code on at least a portion of said information word; and means (36, 40) for modulating said video signal according to a stored data word comprising said start code, said error code, and said information word, said error code being a "coset" code on at least   a part of said registered data word.   2. Device according to claim 1 for coding an information word, I (x) on a horizontal line.   a composite video signal during its erase interval   vertical arrangement, characterized in that said error code generation means (45) produces an error code C (x) using a generator polynomial g (x), said crash code having the form C (x) tI (x). H (x) + M (x) o H (x) and M (x) are constant polynomials; and in that said modulating means (36, 40) modulates said video signal during a horizontal line during its vertical erase interval according to a recorded word   T (x), containing said error code and said informational word   mation; H (x) and M (x) being chosen so that [T (x) 14 0.   3.- Device according to any one of   1 or 2, characterized in that the means   aforementioned to produce the error code is responsive to the information word; in that means are provided for combining said information word and said error code; and in that a means, incorporated in said means for producing said error code, controls the production of said error code so that at least a portion of said data word has an error checking result equal to starting code mentioned above.   4.- Device according to claim 1, characterized in that the aforementioned means for controlling the production of the error code is of a type such that the complete data word has an error checking result equal to the above departure code.   5.- Device according to claim 1 for coding an information word I (x) on the aforementioned video signal,   characterized in that the departure code, B (x) above, corresponds to   feeds to a start sequence; in that the aforementioned means for generating the error code, C (x), uses a generator polynomial (x), said error code having the form C (x) = [I (x). H (x)) + M (x) o H (x) and M (x) are each constant polynomials; and in that the aforesaid modulation means modulates said video signal according to a given data word T (x) given by T (x) = B (x) xm + n + C (x) xm + I (x). the number of bits in said error code and m is equal to the number of bits in said information means, H (x) and M (x) being selected so that [T (x)] = B (x).   6. A decoder device for decoding an information word of a video signal, said video signal being modulated during a horizontal line during its vertical erasing interval according to a stored data word, said stored data word containing a data code. error and an information word, characterized by receiving means (44) responsive to said modulated video signal for detecting the individual bits of a received data word; polynomial divider means (46) connected to said receiver means for dividing at least a portion of said received data word by a constant polynomial g (x), said polynomial splitting means having a remainder output; and control means (50) responsive to said remainder output for indicating that said received data word is valid if the remainder at the output of said polynomial divider   is equal to a predetermined value, said predetermined value   determined not to be zero. 7.- Device according to claim 6 for the restoration of a videodisk, characterized in that said receiver means has an output of the received data word corresponding to the bits of the recorded data word; and has first decoder means (45) for detecting the aforesaid start code; in that said polynomial divider means includes an error check register (62) for dividing at least a portion of said received data word with a constant polynomial g (x); and in that said control means is responsive to said first decoder means and said error check register, said control means including means for setting said register   error checking to a first constant pre-   determined before division, and means for indicating that said received data word is valid if said error checking register contains a second predetermined constant after division, at least one of said first and second predetermined constants being nonnull. 8.- Device according to claim 7, characterized in that the aforesaid starting code is represented in binary form by 1111100110101.   9.- Device according to any one of   Claims 6 or 7, characterized in that the polynomial   constant g (x) supra is given by g (x) = x 3 + x 2+ + X + x7 + x6 + x5 + x4 + x2 + 1.   10.- Device according to any one of   claim 6 or 7, characterized in that the means   polynomial divider is sensitive by means of   aforementioned command to divide all the received data word.   11.- Device according to any one of   claim 6 or 7, characterized in that the means   polynomial divider is responsive to the control means for broadcasting the combined information and the code error of the received data word.   12.- Device according to claim 6 for the restitution of a videodisk, of the type where the aforesaid data word comprises a start code and an information word and an error checking code, characterized in that the means said polynomial divider (62) includes error checking means connected to said receiver means for producing an error checking result;   and that said control means (64) is sensitively   audit means, to indicate that the received data word is valid if at least one   part of said received data word has a verification result   error cation equal to said start code.   13.- Device according to claim 12, characterized in that the aforementioned control means indicates that the above received data word is valid if the complete received data word has a verification result.   error equal to the above departure code.   14.- Device according to claim 12 of the type where the aforesaid data word contains a start code and an information word and an error checking code, characterized in that the said control means is sensitive to the aforementioned rest to indicate that the received data word is valid if said remainder after division by   g (x) is equal to said start code.   15.- Device according to claim 12 for the return of a videodisk of the type o the aforementioned data word contains a start code and an information word and an error checking code, of the type comprising a detector means connected said receiver means for detecting said start code, characterized in that said polynomial divider means divides, in response to a division control signal, at least a portion of said data word received by the constant polynomial g ( x); in that said polynomial divider means comprises a register of the remainder; and in that said control means is responsive to said detector means for   supplying said division control signal after detecting   said start code; said control means further comprising means responsive to the contents of the remainder register to give an indication that the received data word is valid if the contents of said register of the remainder after   division of the polynomial is equal to said start code.   16.- Device according to claim 12 for the restitution of a videodisk, of the type where the aforesaid data word contains a start code and an information word and an error checking code, characterized in that the means said divider includes shift register means coupled to said receiver means, said shift register means having feedback responsive means responsive to a enable signal for multiplying the output of said shift register means by the constant polynomial g ( x) and subtracting the result from the contents of said shift register; detector means connected to said shift register for detecting said start code; and in that the aforesaid control means comprises a sensitive means   detector means for applying the validation signal   to said feedback means when said detector means has detected the start code, and further comprises means responsive to said detector means for detecting the start code in said shift register when the data word is received to indicate that said word of received data is valid.   17.- End of program detection device   in a videodisc turntable for the restitution of a video-   disk having a substantially spiral information track, said information track representing a recorded carrier modulated by a video signal, said   video signal containing information signals representative of   both registered numeric numbers, of the type where a predetermined value of said numerical numbers corresponds to a band of turns of said spiral information track after the end of the recorded video program, said video-disc player comprising a signal reader means for receiving said signal recorded video characterized by detection means connected to said signal reader means for decoding said recorded digital numbers; and control means responsive to said decoded digital numbers for producing an end of program indication signal when said detecting means decodes said predetermined value of said stored digital numbers; said rotating video camera further comprising means responsive to said end of program indication signal;   to pocket the operation of said sensor means.