KR850001311B1 - Digital on video recording and playback system - Google Patents

Abstract

A video disk palyer detects field number information recorded on a sectored video disk and represents stylus location as well as correlates presently received field number information with previosly received field number data to determine whether or not the presently received data indicate the stylus to be playing back from the predicted sector of the disk and within a predicted range of radius from the center of the disk. These range and sector checks are used to reduced the probability of data errors passing undetected during playback.

Description

Improved digital recording and playback system for video

1 is a television signal diagram including a vertical blanking interval between the odd and even fields.

2 is a digital data format used in accordance with the recording method of the present invention.

3 is a block diagram of a video disc encoder according to the present invention.

4 is a block diagram of a video disc player according to the present invention.

5 is a detailed view of the digital data generator in the video disc encoder of FIG.

6 is a detailed view of the information buffer in the video disc player of FIG.

FIG. 7 is a schematic diagram of an apparatus for generating an error check code from information bits for the video disc encoder of FIG. 5. FIG.

FIG. 8 is a schematic diagram partially showing the information buffer for the video disc player of FIG.

9 is an embodiment of the receiver control counter for the information buffer shown in FIG.

10 is a state transition diagram for the microprocessor controller of FIG.

FIG. 11 is a flowchart showing a program algorithm for the microprocessor controller of FIG.

The present invention relates to an apparatus for encoding a digital signal on a video signal, and an apparatus for detecting a digital signal from a video signal. The present invention is particularly useful for a video disk system.

The video disc player converts the recorded parameters on the disc record into standard television signals for application to the antenna terminals of the television receiver. In a preferred embodiment of the video disc system according to the present invention, the subcarrier processing technique buried as recorded in the video signal before the recording is known in US Pat. Is processed by. In the player, the video processing network detects the recorded FM modulated video signal and separates the respective chromaticity and brightness information. This separation is achieved by comb filtering as described in US Pat. No. 3,996,606 entitled “Comb Filter for Video Processing”, issued December 7, 1976 to D.H Pritchard. The chroma signal is then heterodyned at the standard color subcarrier frequency to be converted into the frequency spectrum and combined with the brightness signal. The resulting composite video signal is also converted to a convenient channel frequency in the frequency spectrum for viewing on a standard television receiver.

In addition to the video signal processing, it is desirable that the video disc player be provided with improved features such as detection and automatic skipping at the occurrence of lock groove generation, automatic detection of the end of program run and indicator of the program run time. Locking grooves used in the present invention mean that defects in the record and contaminants on the record surface skip the needle backwards in the program material.

If the viewer or other mechanism does not advance the pick-up device through the lock groove when such a defect occurs, it is very important to detect the lock groove because the program progress is delayed by the lock groove. . Moreover, the above case occurs when the pick-up device is a needle moving in the drive carriage, and even a program break occurs because the needle is destroyed by the lock groove state. Upon lock groove detection, a needle 'kicker' may be used to automatically advance the needle past a disk defect. In fact, if the system detects the lock groove early, the needle can move rapidly through the defect zone without any noticeable interruption to the viewer.

At the end of the program, detecting the end of the program correctly is preferable to merely detecting the signal loss. By detecting the end of the program, the viewer gets an immediate response from the player to change or flip the video disc. An indicator indicating the program running time is particularly useful for the viewer because it can return to a desired position in the program.

Other useful features, in addition to the features mentioned above, are brought about within the preferred embodiment of the present application by recording digital information on the video signal. In particular, digital numbers are assigned to each picture field (or other location indication, such as each home line). Program run time is calculated by dividing the field number by a constant. Basically, lock grooves are detected by detecting at least two noncontiguous field numbers. A more detailed treatment of the problem of lock grooves is described in the pending patent application "Track Error Correction System for Video Disc Player" filed by J. Rustust and M. Mindel at the same time as this application.

Here, other digital numbers referred to as band numbers are recorded in addition to the field numbers to indicate the type of program material. For example, program end detection is performed by detecting a single program end band number. Digiformat has extra unallocated information bits that can be extended to contain other features that will arise in the future.

As mentioned above, the desirability of a system development for recording digital numbers in any form on a video signal will be appreciated. It is known that digital information pre-recorded for one or more horizontal lines can be provided from the digital video system used for video disc recording. The known system uses vertical and horizontal projections to synchronize the player data subsystem to pre-recorded data intervals. Because video discs have time-based changes during playback, some of these systems use body clock waveforms that sample each bit. A typical embodiment of a self clock waveform used in prior art video disc systems is Miller encoding. In Miller format, signal transitions at regular intervals indicate the beginning of a clock cycle, and transitions between clock transitions (or no signal parts) indicate data bits.

A disadvantage of these conventional systems is that video networks require special networks to separate digital bit streams. For example, if data is synchronized with vertical synchronization, vertical synchronization is detected. However, normally vertical synchronization is not used in video disc players, so a separate detector is required. Another disadvantage of conventional systems is that the sync pulse edge is not accurate enough as a reference time for extracting digital data. Video disc noise tends to resemble sync signals. Therefore, it is desirable to completely avoid using the video sync signal to synchronize the digital subsystem to the video signal. In addition, their clock waveforms require more complex detectors and generally have a reduced data rate compared to nonmagnetic clock waveforms.

In the present invention, the video carrier is modulated by the digital data stream in synchronization with the color carrier signal during the horizontal line. Data is represented by brightness levels. Therefore, the video signal is sampled using a color carrier oscillator as a clock to interface the digital system to the video disk system.

The horizontal line adjacent to the line containing the data is at a constant brightness level. Such devices allow the use of useful signals for video disc players. That is, the use of the chromaticity-related output of the comb filter (used here as the processed video) as the data signal is allowed. The processed video is regarded as data, and is sampled continuously at the clock ratio of the color carrier signal. Since the comb filter removes one line from the adjacent line, the processed video signal is self-referenced, and the data error caused by the direct current level of the video signal is removed.

The start code is used to synchronize the digital system with the recorded data. The digital system is successively sampled to find the first start code. The digital system then stores the extras of the digital message and stops the data sample. Microprocessor control is used to calculate the occurrence time of the next start code. The digital system begins to sample the incoming data again shortly before the expected arrival time of the next horizontal line containing the data. In this way, the digital system resynchronizes the incoming data in each field. At the same time, the adverse effect of the digital system on the input signal during times when no data is expected improves the noise immunity of the system.

Thus, in the present invention embodied in a video disc digital recording and reproducing system, a video-digital interface is arranged to remove the dependence of vertical or horizontal synchronizing signals and is useful during video signal processing to detect recorded digital information. Use signals easily.

According to one aspect of the present invention, a video disc recording method is provided for recording a horizontal line of a video signal modulated according to digital information adjacent to a constant brightness horizontal line of the video signal.

In the above method, each bit of digital information is recorded in synchronization with the color carrier of the video signal.

In the video disc reproducing method and apparatus provided by the present invention, each bit of the digital information is detected by sampling the digital information signal in synchronization with the color carrier of the video signal.

Further, in the method and apparatus for synchronizing a digital system to a recorded video signal according to the present invention, the method continuously detects each bit encoded on the recorded video until a first digital message is received. Thereby detecting the first digital message, timing the gating time interval equal to the start video feed interval of each horizontal line containing the digital message, and a data window time interval starting before the end of the gating time interval and extending to the end. And timing whether subsequent digital messages are detected within the data window time interval.

Hereinafter, the present invention will be described in detail with reference to the drawings.

[Signal Format]

FIG. 1 is a detailed view of an NTSC-type television signal formatted by a subcarrier technique buried as described in US Patent No. 3,872,498 entitled “Color Information Transmission System” to D. Pritchard. The vertical blanking interval separates the intersected radix and the even field. Those skilled in television technology will readily understand that the standard blanking interval includes a first equalized pulse interval, a vertical sync interval, and a second equalized pulse interval having multiple horizontal intervals at the beginning of each new field. As shown in FIG. 1, the video signal information starts at line 22 'of field 1 and line 284' of field 2. As shown in FIG.

Digital information representing the field number appears on line 17 'of field 1 and line 280' of field 2. The digital information can be inserted into another line of vertical blanking interval. Figure 2 shows an enlarged view of the time during the horizontal line (line 17 'or line 280') containing data to detail the digital signal format.

Data is displayed in terms of brightness level. That is, the 100IRF unit is logic '1' and the OIRE unit is logic '0'. The first data bit is followed by a standard horizontal sync pulse 140 and a color burst 142. The frequency of burst 142 is a buried subcarrier frequency of about 1.53 MHz. Each data bit is transmitted in synchronization with a buried subcarrier signal at 1.53 MHz. As shown in FIG. 2, the digital message consists of a 13-bit start code B (X), a 13-bit excess error check code C (X), and 51 information bits I (X). The beginning of the horizontal line in the next order is indicated by the horizontal sync pulse 140a and the color bust 142a in the next order. Thus, each data bit is in sync with the color carrier, and the entire digital message is in sync with the vertical sync pulse. The data rate may be a multiple or a divisor of any convenient subcarrier carrier. Other brightness values may also be assigned logical ones and zeros, and one or more bits may be associated with a given brightness level.

The cachecode is used to synchronize digital messages and data systems in the system, eliminating the need to detect horizontal or vertical synchronization edges. Synchronization errors in a series of digital data systems result in framing errors, where the received data is shifted one or more bits from the appropriate location of the data. Previously known systems for recording encoded digital signal data on a video disc are known to cause framing errors because the synchronization signal delay is not certain on a time basis. Now, we will more clearly prove the existence of the start code.

The specially selected start code 1111100110101 is one of the Barker codes known in the radar and solar technology. R.H., published in 1953 by Academic Press, New York City, NY. See Barker's Binary Digital System Group Synchronization. Barker code is designed to exhibit self-correlation, where the self-correlation function of the signal containing the code moved relative to itself is at its maximum when matched with each other, and otherwise minimum. In other words, when the value of +1 or -1 is assigned to each bit of the start code, and the sum of the amount of bits for the position of the shifted start code with respect to itself is calculated, this self-correlation function is the correct maximum value when it coincides with each other. Will cause In particular, a Barker code moved to a certain radix position with respect to itself forms a zero autocorrelation. A Barker code that has been transitioned to some stormwater position relative to itself forms a self-correlation of -1. But when they coincide with each other, N is autocorrelation. Where N is the number of bits in the Barker code. In other words, the Barker code moved to a certain number of positions for itself has a different maximum number of bit positions. When noise is present, this characteristic reduces the probability of start code misdetection compared to a randomly selected start code.

The information bit I (X) includes a field number, a band number, and redundant information bits. The field number is the same as the video signal of each field by a single 18-bit binary number. At the beginning of the video disc, the first field of the video program is field "0". Each field then becomes a number that descends continuously. The band number is a video signal recorded in an adjacent line group of spiral grooves having a shape similar to that of a major edge. All of the materials in this home band have a common band number.

As in the embodiment of using the band number, the video signal is recorded in the 63rd band after the end of the video program. The video disc player detects band number 63 as the end of the program and lifts the needle from the record.

The error check code C (X) is calculated from I (X) of the video disc recording apparatus. To do this, I (X) is multiplied by the constant H (X), which is divided by another constant g (X). In this way, after the division is made, the remainder (the quotient is not used) is added to the third constant H (X). The result is C (X).

In a video disc player, the received message is checked for error by dividing the previous message containing the start code by g (X) described above. If the remainder is equal to start code B (X), the message is correct data. The constants H (X) and M (X) are chosen such that the remainder of the previous message can be the start code. The constant g (X) used in both the video disc recorder and the video disc player is called the 'generation polynomial' of the code. When applied to a video disc medium, a particular g (X) is selected that generates a code with particularly advantageous error detection characteristics. In the present system, the above addition, multiplication, and division operations are performed in accordance with special rules of hardware for performing this. Error coding will be described in detail later with respect to encoding and decoding hardware.

3 is a block diagram of a video disc encoder. The adder 36 linearly combines the composite video signal from the signal source 30 with the digital data bit stream on the leads 37 supplied by the digital data generator 38. The synchronizing device 32 supplies the color subcarrier and the synchronization pulse so that the data bits generated by the digital data generator 38 are synchronized with the color carrier generated at the terminal 31a, and the digital message is vertical blanking interval. Make sure that it is encoded on the appropriate horizontal line within it.

Information bits, including video field numbers and band numbers, appearing on the data bus 39 are provided by the device 34. The use of the field number and band number information will be described in connection with the microprograms (FIGS. 10 and 11). Digital data and video signals are combined at adder 36. Furthermore, the signal processing device 40 adjusts the composite video for the recording medium. The composite video signal is a buried subcarrier and is recorded using FM modulation.

In the video disc player of FIG. 4, the FM signal is detected using the pickup converter and the needle component 20, and converted into a standard television signal so as to be reflected on a conventional television receiver in the video signal processing network 18. The video signal processing network 18 includes an apparatus responsive to a color burst signal for phase locking a color local oscillator of 1.53 MHz to a color half-wave. The color local oscillator is used not only to demodulate buried subbands but also to provide a digital clock signal on lead 72. The video processing network 18 also includes a device for demodulating the video carrier and comb filtering the regenerated video signal. The comb filter 19 deletes two adjacent field lines occurring on the conductive line 70 as processed video. Since the line 16 'existing at the black level is deleted from the line 17' modulated together with the digital data, the processed video on the conductive line 70 is reproduced digital data. Naturally, line 16 'will be at any constant brightness level. If the continuous line 18 'to the data line 17' is a constant brightness line (also black level), the continuous output of the comb filter during line 18 'is again reproduced digital data or the data is inverted. . By deleting one line from a constant adjacent brightness line, the reproduced digital signal becomes a self reference, thereby eliminating data error due to the DC level shift of the video signal. If it is desirable to place data on a continuous line rather than a data position adjacent to a constant light line, an apparatus for presenting the video signal at a predetermined brightness level or a direct current reference level is needed to separate the video signal from the digital data stream.

As shown in FIG. 4, the information buffer 16 extracts digital data from the video signal in response to the processed video signal on the lead 70 and a clock signal of 2.53 MHz on the lead 72. FIG. The buffer 16 is controlled by a digital binary control signal on the lead 71 from the microprocessor 10. In one binary state, the control signal on lead 71 is due to information buffer 16 acquiring data. In another binary state, the control signal on the lead 71 adjusts the information buffer 16 to send the received data to the microprocessor 10. In particular, when the control signal on the lead 71 is at a high level, the information buffer 16 is opened to sample incoming data on the video signal lead 70 processed using the 1.53 MHz signal on the lead 72 as a clock. . After the complete message has been received, the status signal on lead 75 provides an indication that the message is complete. In order to deliver a message to the microprocessor memory, the control signal on the lead 71 is at a low level. This action closes the information buffer, resets the internal control circuitry, and gates the result of the message error code check on the status line 75. If the status signal indicates that the message is valid (i.e. when the error code check indicates certainty), then the microprocessor 10 will externally clock on the lead 73 to transfer data from the information buffer 16. Supply the signal. For each clock pulse, one data bit on lead 74 is passed from the information buffer into microprocessor 10, and when the program is ready for another digital message, control lead 71 returns to a high state. The process is repeated and the process is repeated.

The microprocessor 10 controls the gating of the line 17 '(or line 280') from the video signal via the information buffer 16. The first digital message is obtained by continuously detecting the video signal for the start code. After that, the information buffer is closed. Therefore, based on the arrival time of the first digital message, the information buffer opens approximately six lines before the next digital message is expected. If no valid message is found, the information buffer 16 closes six lines after the expected arrival time. If a valid digital message is found, the information buffer 16 is closed and a new arrival time for the next digital message is calculated based on the arrival time of the current digital message. In this way, the microprocessor opens a gate or " data window " approximately 12 lines wide to concentrate on the expected data. The time interval from the center of one data window to the next is approximately one video field time interval. The width of the data window is chosen so that the expected data fits the data window under the worst timing conditions. As will be explained, the timing right dimension is a limited analysis of the digital timer, the flow ratio of the timer, the uncertainty of the program that determines the current data arrival time, the timing difference between the odd and even interlaced fields, and the like. Alternate use of the microprocessor and timer can be adjusted by adjusting the width of the data window. The microprocessor program that controls the logic to focus the data window and detect the data is discussed next with reference to FIGS.

The microprocessor 10 responds to the player panel control 14 (load, stop and scan) to operate the player device 12, and also drives the player display unit 22 in accordance with a selected program. The player machine is provided with at least one needle “kicker” operated by the microprocessor 10. Kickers are piezoelectric, electromagnetic or other devices for impulsively moving signal pickup devices to adjacent grooves or signal tracks on a video disc medium. The use of the kicker for the breakout of the lock groove will be discussed later in connection with the flowcharts of FIGS. 10 and 11.

As mentioned above, the video disc recording apparatus uses the information bit I (X) to calculate C (X). Many of the potential bonds-I (X) and C (X) are 64 bits long. Error codes are mathematically processed because they are also required to determine the error detection and correction characteristics of a given code without having to reclassify them one by one. The mathematically improved ring theory and Galois fields GF (2 ^m ), which can be applied entirely to error codes, are mentioned in the W. Wesley Peterson book "Error Correction Codes" filed by MIT Publishing, Cambridge. For the purposes of the present invention, error coding in a video disc can be easily understood with a few simple definitions. A digital message consisting of 1,0 is an algebraic expression expressed as the sum of the powers of X. Each X series of coefficients is a bit for each message. For example, the 4-bit message 1011 can be represented by the polynomial P (X), where

P (X) = I · X ³ + O · X ² + I · X + I · X ⁰ = X ³ + X + I

Applying this notation to the opening code 1111100110101

B (X) = X ¹² + X ¹¹ + X ¹⁰ + X ⁹ + X ⁸ + X ⁵ + X ⁴ + X ² + I

The highest X series is the order of the polynomial. In the above, B (X) is 12th order.

Polynomials can be added, subtracted, multiplied, and divided using conventional algebra, except for modulo-2 coefficients. After dividing into another polynomial, a simple representation of the rest of the polynomial can be represented by a bracket.

The remaining r (X) has a lower order than the jet number g (X), where [P (X)] = r (X). This means that the rest of P (X) is.

In a video disc recording apparatus, the total message recorded on the video disc is denoted by the polynomial r (X). (2) T (X) = B (X) X ⁶⁴ + C (X) X ⁵¹ + I (X)

Then X ⁶⁴ is characterized in that since the B (X) is the beginning of a data formatting the B (X) 64bit transition. Similarly, the X ⁵¹ term transitions C (X) 51 bits to indicate that C (X) is written before I (X). The recorder divides the total message T (X) by g (X) and then calculates the value of C (X) to have the same remainder as C (X). In other words,

C (X) is set to C (X) = [I (X) -H (X)] + M (X)... (2) masquerading as

H (X) and M (X) are [T (X)] = B (X)... Is a constant polynomial chosen to be (3).

Solving equations (1), (2) and (3) for polynomials H (X) and M (X)

It can be seen that H (X) = [X ¹²⁷ ] M (X) = [B (X) X ¹³ + B (X) X ¹²⁷ ].

FIG. 7 includes a table showing the selection values for B (X) and g (X) as well as the inductions for H (X) and M (X). The table in FIG. 7 shows the higher order bits from the right side, which are the same order as the flip-flop store in the logic diagram.

In a video disc player, the recorded digital message is read by the electronic player. The data recorded on the video disc is R (X). The data read by the player is R (X). T (X) = R (X) if no error occurs between recording and playback. The error is checked by dividing the received message R (X) by g (X). If the remainder is equal to start code B (X), then the message is considered to be correct data with no error. On the other hand, if the remainder is not equal to B (X), an error is displayed accordingly.

The code characteristic generated by the above method depends on the selection of g (X), called the generator polynomial. One of the computer-generated codes demonstrated by Tadao Kasami in "Optimal Reduction Hand Codes for Burst Error Correction" published in the IEEE report in 1963. Burst errors in digital systems are errors that occur when adjacent bits in a digital message are lost. Burst error is quite similar to the transmission error type of video disc media. As known by Kasami mentioned above, a code capable of correcting up to six single burst errors is

g (X) = X ¹³ + X ¹² + X ¹¹ + X ¹⁰ + X ⁷ + X ⁶ + X ⁵ + X ⁴ + X ² +1

Can be constructed using the given polynomial given by Furthermore, for a given g (X) all single burst errors of 13 bits or less will be detected, and all single burst errors longer than 13 bits will be 99.988% capable of error detection. As described here, a video disc player uses only the error detection capability of the selected code.

As a specific embodiment of the error code generator, considering the case where the field number is 25,000, the band number is 17, and the spare bit is 0, the binary representation of 25,000 is 000 110 000 110 101 000, and the binary representation of 17 is 010 Since it is 001 (the higher order bit from the left), the 51-bit information bit is 000 000 000 000 000 000 000 000 000 000 000 110 000 110 101 000 010 001. The transmission order is the reserved bit followed by the field number first and the next band number. In this case, the best bit is transmitted first. The error code for I (X) is calculated as the remainder of I (X) .H (X) + M (X) and is indicated by 0111100100010. The next video field is 25,001 and the corresponding binary representation is 000 110 000 110 101 001. Accordingly, the information bit is 000 000 000 000 000 000 000 000 000 000 000 110 000 110 101 001 010 001 and the error code is 1000101101110. Therefore, the complete digital message for field 25,000 containing the initiation code is 1111100110101 1000101101110 000 000 000 000 000 000 000 000 000 000 110 110 000 110 101 001 010 001. The start code is the first 13 bits, the error code is the next 13 bits, and 51 information bits are last. In a video disc player, the digital message is checked for error by dividing the received message with. If no error is detected, the remainder is 1111100110101, which is exactly the start code.

[HARDWARE]

A block diagram of the apparatus for generating T (X) is shown in FIG. Under the control of the transmission control device 50, 24-bit information bits pass through the data bus 39 and 27-bit information bits are loaded into the 51-bit shift register 44 via the data bus 39a. Therefore, I (X) consisting of these 51 bits is moved into another 51 bit shift register 52.

At the same time, for 51 shift pulses, encoder 45 calculates C (X) in the following manner. The polynomial division multiplier 46 calculates the remainder of I (X) -H (X) / g (X) in response to 51-bit serial transmission of I (X). M (X) is then added in parallel to the polynomial adder 48. The resulting code C (X) moves to the 13-bit shift register 54, and the start code B (X) moves to another 13-bit shift register 47 via the data bus 49. Since the start code is a constant digital value, it can be applied by a fixed connection to the parallel load input of the shift register 47. In positive logic notation, when the start code has zero, it corresponds to the shift register 47. The parallel input is connected to the ground potential, and when the start code is 1, it is connected to the static potential. The transmission control device 50 controls the total message T (X) contained in the three shift registers 52, 54, 47 shifted in series with the color carrier and the register on the conductive line 31a. The video sync pulse applied to the conductive wire 33 is supplied to the transmission control device 50 at a reference time so that the digital message is transmitted at an appropriate time for the video signal.

A particular embodiment of the encoder (45 of FIG. 5) is shown in FIG. Clock flip-flops with output terminals Q ₀ through Q ₁₂ form the remaining registers. The operation of multiplying H (X) and dividing by g (X) is performed in series at the same time bit by bit. The remainder is then retained in the remaining register outputs Q ₀ through Q ₁₂ . General processing of these circuits is described in Peterson's Chapter 7, pages 107 to 114, mentioned above. In order to simplify the circuit of FIG. 7 for the property and multiplication of the polynomial, addition and subtraction are performed by addition and subtraction exclusive gates on the coefficients of the alumni term. The operation of multiplying I (X) by H (X) is performed by properly connecting one or more exclusive OR gates 80-91. For example, if only the coefficients of H (X) and not g (X) are 1 (bit positions 1, 3, 8), then input I (X) is an exclusive OR gate (80), (82), (87). Each connected to an input. When dividing I (X) by g (X), multiply the output of Q ₁₂ by g (X) and subtract that product from the quantities of registers Q ₀ through Q ₁₂ . In addition, when only the coefficient of g (X), not H (X), is 1 (bit positions 4, ₇ , 11), the output of Q ₁₂ is connected to the inputs of the exclusive OR gates 83, 86, 89, respectively. . At positions where H (X) and g (X) are both 1 (bit positions 0, 2, 5, 6, 10, 12), the output of exclusive OR gate 91 is exclusive OR gates 81, 84, 85, 88 and 90, respectively. After 51 clock pulses, one for each bit of I (X), the contents of registers Q ₀ to Q ₁₂ become the remainder of I (X) and M (X) after dividing by g (X).

Note how the contents of the remaining registers are added to M (X). The addition of the coefficients is the modulo-2 calculation method performed by the exclusive OR function. When M (X) has a coefficient of +1, the complementary output Q of the corresponding flip-flop is used, and when M (X) has a coefficient of zero, the non-maintenance output Q is used.

A block diagram of the apparatus for decoding the received message R (X) is shown in FIG. 6, which is an embodiment of the information buffer of FIG. 4 described above. The control signal input on the lead 71 controls the receiver decoder of FIG. 6 to receive data from the video signal or to send data to the microprocessor.

In the receive state, each bit is simultaneously shifted into two separate registers. One such register 60 is for data and the other register 62 is for error checking. The catcher check register 62 is a polynomial division circuit. However, when new data is received, the divide feedback line stops operation and acts directly as a shift register. The operation of division register 62 will be described in more detail in conjunction with FIG. For this purpose the register 62 will be described in more detail with reference to FIG. 8 in the operation of the receiver control device 64. For this purpose, the register 62 operates to shift the continuous bit of R (X) or divide the continuous bit of R (X) by g (X) in response to the receiver control device 64. In either of these cases, the contents of register 62 reside on data bus 78, which is provided to start code and valid data detector 66.

The receive operation begins with a register 62 that is adjusted to act as a shift register. After B (X) is detected by the detector 66, the controller 64 adjusts the register 62 to operate as a polynomial divider circuit. Thus, dividing the polynomial by g (X) begins with the divide register with B (X). The receiver controller 64 also times out the same period as the remaining message bits (64 clock pulses) in response to the detection of B (X). After the timeout period, divider 62 includes the remainder of R (X) divided by g (X), where the remainder should be B (X) if the message is correct. During the error check process, the data register 60 is shifted by data bits. At the end of the timeout period, data register 60 stores only the last 24 bits. However, since the 24-bit information bits are located at the end of the message, register 60 will contain the allocated information bits. If it is desired to use the spare information bits, additional shift register stages may be added.

The interpretation of the output state signal on the lead 75 depends on the state of the control signal on the lead 71. When the control signal on the lead 71 adjusts the receiver to obtain a data state signal (receive state), the status signal on the lead 75 is defined as "receive a message". When the control signal on the conductive line 71 adjusts the receiver to transmit data (transmission state), the status signal on the conductive line 75 indicates "valid data". The control signal of the lead 71 also resets the receiver control device and gates the result of the remaining check with the status signal on the lead 75.

The received signal is transmitted from the shift register 60 in response to an external clock on the lead 73 supplied by the microprocessor. After the data has been seeded, the control signal on lead 71 will return to its original state and be adjusted again to continuously detect another start code.

8 is a schematic diagram and logic diagram of a couple of receiver receivers of FIG. Flip-flops with output terminals Q ₀ ′ to Q ₁₂ ′ form the remaining registers. The polynomial division by g (X) is achieved by multiplying the continuous register output term from Q ₁₂ 'by g (X) and subtracting the multiplied amount via the exclusive OR gates 100-108 from the remaining register amounts. The feedback operation from the Q ₁₂ 'through the NOR gate 109 is performed through the gate since the exclusive OR gate is set to the bit where g (X) has a coefficient of 1 except the coefficient for bit 13. Since the coefficient of g (X) is 1 for bits 0, 2, 4, 5, 6, 7, 10, 11, and 12, the exclusive OR gate is the data input of the flip-flop at the corresponding position of the remaining registers as shown. Is located in. NAND gate 118 detects B (X), which is both a start code and a valid error check code. The receiver control counter 1117 starts counting in response to the start signal from the AND gate 120 to count 63 clock cycles, and is used in the NAND gate 111 to stop the clock for all decoder flip-flops. Supply stop signal. A typical embodiment of the receiver control counter 117 consisting of seven flip-flops 130-136 is shown in FIG.

The continuous reception of data is as follows.

When the control signal on the conductive line 71 is at the high level, the data is gated to the polynomial divider register 62 through the AND gate 110. The polynomial divider register acts as a shift register by presetting flip-flop 119 and blocking NOR gate 109. Upon detection of B (X), the output of NAND gate 118 is at a low level, and the Q output of flip-flop l19 is at a low level after one clock. Therefore, feedback allows the polynomial to be divided by the output of AND gate 120 via NOR gate 109 when B (X) is detected in the remaining registers. After 63 clock cycles, the receiver control counter 117 stops, and the status signal on the lead 73 rises to a high level to indicate " message reception ". Shift register 60 holds the last 24 bits of I (X). For data transmission, the control signal on the lead 71 becomes low level. If the remainder after division is equal to B (X), the inverting output of the NAND gate 118, which is at a low level, is gated with a state signal on the conductive line 75. The external clock pulse on the conductive line 73 shifts the continuous data in the register 60 to the output data signal on the conductive line 74. The external clock pulse also clears the remaining registers by shifting zero to the remaining registers.

The apparatus described above shows the start and end of the remaining registers having the same non zero constant. However, it will be understood that other devices are possible when the coset code is used. For example, after the detection of B (X), the remaining registers can be set to a first constant. After the property is made, the remaining registers are checked for the appropriate second constant. The first or second constant may be zero or both may not be zero.

Observe the simple hardware that forms the error code format described here. The start code detector (NAND gate 118) acts as a valid code detector by ending with start code B (X), which is the remainder of the validity. Since the division starts with the start code in the polynomial division register, the control step is performed so that the remaining registers are not cleared.

Typically, the error code is located at the end of the message. However, by placing the error code before the information bit, the receiver controller does not need to distinguish between the error code bit and the information bit for the 24-bit shift register (or data storage register) 60, which simplifies. In addition, as shown in FIG. 8, the receiver controller is a simple counter 117 having a start terminal and a stop terminal and providing a timing out for one time interval.

Digital information, including band numbers and field numbers, is recorded in the video signal and used by the player to form various forms. The band number information is used by the player to detect driving end (band 63). The field number information in ascending order is used to calculate and display the program travel time on the LED display device 22 of FIG. If the program length is known, the field number information can be used to calculate the remaining program running time.

For NTSC type signals, elapsed program time per minute can be obtained by dividing the field number by 3600. If desired, the remaining program time may be derived from the previous calculation. This feature is useful for viewers when they want to inject the desired part of the program. In particular, the features derived from the field number information will be described later in relation to the tracking error, which is a more general case.

The field number indicates the actual needle position. Thus, the actual needle position can be determined from the first valid field number reading after the track has been jumped or when the needle has entered the groove again after the injection device has been operated.

Since both the track error correction system and the program travel time display use the field number data, the decoding portion of the video disc digital data system is shared. A particular embodiment of the track error correction system to be reviewed later uses field number data (needle position) to keep the needle at or before the expected position assuming the relative speed of the predetermined needle and record. The program run time display, another representation of the needle position, uses field number data to indicate the run time.

The microprocessor controller has several internal modes. 10 is a state transition diagram indicating mode logic executed by a microprocessor program. Each circle represents a machine mode: load, spin up, acquire, drive, stop, run latch and end. For each mode, the position of the needle and the indicator state are displayed inside each circle. Arrows between modes indicate the logical combination of signals supplied by panel control (load, stop, scan) causing a transition from one mode to another. The load signal indicates that the player machine is in a state for receiving a video disc. The stop signal is derived from the corresponding control panel switch, and the scan signal indicates the operation of the syringe system.

After the power is turned on, the system is in load mode. The video disc can be loaded onto the turntable in this mode. After loading, the player enters spin-up mode, which rotates the turntable at full speed of 450 RPM for a few seconds. The acquisition mode is entered at the end of the spin up mode.

In acquisition mode, the digital subsystem lowers the needle to continuously detect "good read". In the acquisition mode, "good read" is defined as the valid start code and valid error check remainder. After a "good read" is detected, the system enters the drive mode.

In the travel mode, the microprocessor sets the field numbers in the order expected in the memory. The expected field number is either a field incremented or a new field number. For the entire successive read, the microprocessor uses the expected field number to perform two additional checks to improve the retention of data.

The first part check is a partition check. The video disk of the embodiment includes eight fields in all circuits divided into eight compartments. Because the compartments have a fixed physical relative position, the compartments follow a cyclical sequence as the disk rotates, even if the needle jumps through multiple grooves. Even if digital information cannot be read for more than one field, the microprocessor keeps time while the needle jumps to the new home and thus the expected field number increases. When a needle is set in the new groove to pick up a new digital message, the new field number is checked against the expected field number. If the partition is incorrect, the data is considered "bad".

The field number is represented by an 18-bit binary code. Partition information is obtained from the field number by dividing the field number by 8 and finding the remainder. However, it contains eight fields in every divided rotation. Because the compartments have a fixed physical relative position, the compartments follow a cyclical sequence as the disk rotates, even if the needle jumps over multiple grooves.

Even if digital information cannot be read for more than one field, the microprocessor keeps time while the needle jumps to the new groove and thus the expected field number is incremented. When a needle is set in the new groove to pick up a new digital message, the new field number is checked against the expected field number. If the partition is incorrect, the data is considered "bad".

Field number 18 is represented by a binary code of a bit. Partition information is obtained from the field number by dividing the field number by 8 and finding the remainder. However, note that the three least significant bits count modulo-8. Therefore, each of the three least significant bits of the new field number must be equal to the three least significant bits of the expected field number in order to pass the partition check.

The second check of data retention is an area check, which is a test for the maximum area of needle movement along the disc radius. When the worst case happens in any mode, 63 grooves are jumped. The home number is indicated by the 15 upper bits of the field number. The microprocessor subtracts the current home number from the expected home number. If the secondary is larger than the allowable area of 63 grooves, this data is considered "bad reading". Otherwise all other reads are considered good reads and the expected field number is raised. After fifteen continuity failure readings, the system enters acquisition mode again.

Further, as shown in FIG. 10, the transition to the acquisition mode is caused by the presence of a scan signal in a certain mode.

When proceeding from the acquisition mode to the travel mode, the microprocessor sets the bad read count to 13. This means that when entering the driving mode from the acquisition mode, either good reading of one of the two fields in the sequence is provided or the bad reading count reaches 15 and returns to the acquisition mode.

If the stop button is pressed during the drive mode, the system enters the stop mode. In this mode, the needle is separated from the record and held in the spinning position on the record. When the stop button is released, it enters the stop latch mode and remains there. When the stop button is pressed, the stop latch mode is relaxed to enter the acquisition mode. When the band number 63 is detected, it goes from the running mode to the end mode.

11 is a flowchart of a program executed by a microprocessor. The microprocessor hardware includes an interrupt line and a programmable timer. A microprocessor suitable for the present invention is Fairchild's semiconductor model F8.

The microprocessor uses a timer to control the window at the time the information buffer detects the data. This "data window" is approximately twelve horizontal lines wide and focused on the expected data. When no data is found, the timer keeps the internal program synchronized at one field time interval.

The microprocessor interrupt is coupled to the status signal on lead 75 (FIG. 4). Interrupts only work in acquisition mode when the system continuously detects data. The program is interrupted when a digital message is received. An interrupt service routine (not shown) sets an interrupt flag when error codecheck indicates valid. Then, in the drive mode, a programmable timer is used to indicate the measured arrival time of the next digital message.

Switch inputs (load scan and stop) are adjusted to prevent the switch from causing unwanted player response. The microprocessor program includes logic for debounce switch inputs. Debounced switch values are stored in memory.

A separate debounce count is maintained for each switch. The switch is sampled and compared with the stored switch value to check debounce 154. If the sampled state and the stored state are the same, the debounce count for that switch is set to zero. The switch state is sampled as often as possible. In each field (16nilise-cond over NTSC), all debounce counts are unconditionally increased. If the debounce count of the result is greater than or equal to 2, the stored state is raised to a new value (debounce). The new switch state acts accordingly.

After the power is turned on, the programmed first step (FIG. 11) is the starter 150, which is an element of every program. The timer is set to time out one video field and the mode is set to 'load'.

The next step 152 is a program for performing the state transition logic shown in FIG. The debounce count is incremented normally at this time and tested to determine if the new switch state is fully debounced.

After mode selection logic 152, the program enters loop 153 (1), samples the switch setting debounce count to 0 (l54), (2) checks whether the timer is closed for timeout (155) (3) It is checked if the interrupt flag is set (156).

If the interrupt flag is set 156, the program transfers data from the information buffer 157a and sets a timer 157b to time out the new field interval. When the interrupt service routine sets an interrupt flag, the contents of the timer are stored in memory. Thus, the program uses the pre-stored timer contents to set the timer 157b to an exact value that roughly anticipates the time of occurrence of the next digital message. As described above, even if the data indicates the first good read in the acquisition mode, the defective count 157c is set to thirteen.

If the interrupt flag is not set, the program branch as a timer is closed to time out (155). If the machine is not in drive mode, the timer is set to timeout 158 at 159 another time interval. . If the machine is in the drive mode, then at 159 a number of time threshold tasks are designated to be executed 160. A data window with approximately six horizontal lines is opened before the expected data. The received data is read and checked as described above (by setting the control signal on the conductive line 71 in FIGS. 1 and 8 to logic '1'). After data has been received or if no data has been received, the data window is closed. The timer content indicating the actual arrival time of the digital message is used as a correction factor to set the timer again (160b). Therefore, the timer is set to focus the next data window over the expected arrival time of the next digital message based on the actual arrival time of the current digital message.

The anticipated field number is raised (160c), the band number is checked for start (band 0) and end (band 63) of driving (160d), and the bad read count is increased for bad read. (160 g). For valid field data in the program observation material, time is calculated and displayed (160f). If the valid field data indicates that the needle has been skipped backward, the needle kicker device is activated to enter the acquisition mode (160e). When the defective read count reaches 15, the device enters the direct acquisition mode. During the time used for the threshold task 160, the switch debounce checkroutine is repeated periodically so that the switch is tested as often as possible. The program returns unconditionally to loop 153 waiting for timer test 155 or interrupt check 156 via mode selection logic 152 to indicate the arrival of the next digital message.

The timer can be set by directly loading the timer via a programmed command. However, it is best to set the timer by setting the location of the memory (display) corresponding to the timeout state of the timer, rather than using a continuous command. The timer is therefore free to run. The timeout or closure to the timeout is detected by comparing the contents of the timers in the display set of memory. The predetermined next timeout state is set by adding a predetermined next time interval to the contents of the preceding timer and storing the result in the memory. Thus, the timer 'sets' each time that valid data is received or no data is received in the data window by setting a new mark in memory corresponding to the next timeout state.

The programmable timer of the microprocessor used in the device described above is controlled by a program to divide the cycle of the input 1.53 MHz clock by a factor of 200. Thus, the timer counts once for every 200 cycles of 1.53 MHz. One vertical field (1/60 seconds for NTSC) is approximately 2128 timer counts. 1.53MHz clock difference? Using a timer that counts multiplication or a timing source independent of the video signal may be used instead.

The data window is wide enough to allow for multiple timing errors. The timer uncertainty due to the limited analysis of the timer is equal to one least significant bit corresponding to the two horizontal lines. Since the 128-timer does not count exactly one vertical field, the accumulated equality error appears somewhat below one line after 16 consecutive fields where no valid message is found. It is noted that the timer that counts the corresponding multiple of the color carrier clock has a flow ratio of zero because the 1.53 MHz color carrier clock is an odd multiple of the line frequency band. In the particular device described herein, the program uncertainty that determines the arrival time of the data is about 1.5 lines or about 97 μS. As a result, because the field is interlaced, the time after one digital message rotor is 262 lines or 263 lines depending on whether the field is odd or even. Although the program can keep track of odd and even fields, it is simpler to widen the data window by adding one line. Combining the above factors, the data window in which three timer counts (about 6 lines) are expanded before and after the start of the expected data is adjusted to allow the worst case timing state.

As mentioned above, the field number information can be used to detect the lock home. If the new field number is smaller than the expected field number (after partitioning and area checking), the needle is skipped backward and repeats the tracking of the already run line (s), i.e., the locking groove. If the new field number is larger than the expected field number, the needle is rotated forward, ie toward the record center. In the present application, skipped grooves are ignored, and if the new field number is large (through partition and area check), the expected field is updated with a new field. In other applications where video discs are used to record digital information on many horizontal lines, skipped grooves need to be well detected and corrected. However, in this video application, the lock groove is corrected by operating the needle 'kicker' until the needle returns to the expected track. Eventually, the needle will proceed past the lock groove.

In a more general aspect, the use of field number information according to the present disclosure provides an accurate device for detecting general tracking errors. In any video disc system, including optical and grooveless systems and having spiral or circulating tracks, detection and induction of tracking errors due to contamination are always possible. The system provides an apparatus for detecting and correcting such tracking errors of a video disc player. For complete tracking, a two-way kicker device is provided to move the pickup forward or backward of the program material. Thus, when a tracking error is detected, the two-way kicker device is moved in accordance with the steep track or lock track.

Although a regular pickup servo can be used for track error correction purposes, a separate kicker or pickup repositioning device is more preferred. Normal servos are typically tuned for stable tracking of spiral signal tracks and do not have adequate characteristics in response to sudden tracking errors.

On the other hand, the separate kicker can be adjusted to provide the rapid response response that is needed, especially to correct the tracking error. A particular embodiment of a kicker suitable for use in the disclosed device is assigned to the assignee of the present invention and is filed by E.Simshauser on May 15, 1979, entitled `` Track Skipper Device for Video Disc Player ''. It is mentioned in

Various control algorithms are possible. The pick-up device can be directly restored to the calibration track by generating a needle motion proportional to the magnitude of the detected tracking error. Alternatively, the kicker may be activated in response to a series of pulses, where the number of pulses is proportional to the magnitude of the detected tracking error. The pickup is moved to the given track number per pulse until the needle is restored on the expected track. For any application (retrieving digital data stored on a video disc medium), it is desirable to return the pickup to the breakaway point so that the pickup attempts a second read rather than returning the pickup to the expected track. In some cases, by using the kicker and proper control logic, successful tracking can be obtained even if it contains defects or contaminants due to tracking errors that the video disc cannot tolerate.

In digital track calibration systems, protection against undetected data errors is necessary to prevent noise signals from unnecessarily advancing or delaying pickup. The data system reduces the possibility of reading undetected data to a negligible level.

Approximately, one can measure the likelihood that any data entry will occur in the data system as a valid message containing a discontinuous field number, whereby the needle kicker acts. The probability of a good cachecode is 1/2 ¹³ . The probability of a good error code is also 1/2 ¹³ . The random probability of the good field number is calculated as follows. The field number contains 18 bits. The most significant 3 bits of each field number indicate the partition number that should match the expected partition number. The remaining five bits representing the home number can be changed over the allowable area (± 63 grooves). Only 126 of 2 ¹⁸ random field numbers will pass parcel and area checks. If the excess information is included, the probability of non-detection error is 126/2 ⁴⁴ .

The calculations are calculated assuming an actual arbitrary input and do not take into account various factors that reduce the probability of non-detection error. For example, burst noises with error bits on video disc tracks adjacent to each other are more likely than other forms of noise. As mentioned above, the particular error code selected detects every single burst error up to 13 bits and, in the case of longer bursts, a higher percentage. Further, as described above, the selection of the non-zero remainder for the error check code (corset code) reduces the possibility of an error not detected. Furthermore, the selected specific start code, which is a Barker code, reduces the likelihood of noise causing false start code detection.

Published data systems applied to video disk systems cause relatively low undetected error rates and significantly reduce false alarms that cause unnecessary needle movement. Data protection provided by the published system improves the stability of many player functions, such as an indication of program run time, which depends on the recorded digital data for proper operation.

Claims (1)

In a microprocessor-controlled video disc player for playing a video disc on which a video signal including a color subcarrier signal frequency is recorded, the video signal includes a digital information signal encoded during a horizontal line of the video signal, wherein the digital information signal is A signal pickup network for synchronizing with a color carrier signal, the horizontal line having a signal corresponding to a constant brightness level, always adjacent to a horizontal line encoded with digital information, and reproducing a signal recorded from a disc record; A video disc player having a video processing network responsive to a given signal, said video disc player comprising: a video processing responsive to said color carrier signal to generate a clock signal synchronized with a color carrier signal and having a periodicity equal to a predetermined frequency thereof Network (18) And a comb filter 19 for generating a self DC-reference difference signal 70 responsive to the recorded digital information signal by deleting the encoded horizontal line having other digital information from the encoded horizontal line having digital information. And simultaneously detect the recorded self-referenced digital information signal in response to the clock signal, and generate a gating time interval in response to the clock signal and the digital information signal, and continuously digital information at an end point of the time interval. An improved digital recording and reproducing system of a video recording and reproducing system, comprising an information buffer (16) for storing the digital information signal for use by a microprocessor (10) for generating a control pulse for operating the information buffer to receive a signal.

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