SU1277428A1 - Digital corrector of time distortions of secam televison signals for video tape recorders - Google Patents

Abstract

The purpose of the invention is to improve the accuracy of the correction by suppressing noise in the entire interval of the damping pulse, to obtain the standard rise time of the damping and synchronized pulses, to improve the quality of the compensation of depositions and to regenerate the signals of the test lines during reproduction with a non-nominal speed of the tape movement. The device contains ATSN 1, charger 2, block 3 for separating luminance and chrominance signals, shaper 4 clocks, detector 5 depositions, shaper 6 pulses of deposition of chrominance signal, multiplexers 7, 13, 15, 21, LZ 8 and 9, sync selector 10, shaper 11 pulses 12.5 Hz, addressing block 12, digital black limiter 14, comparator 16, driver 17 of clock and damping pulse codes (FKSIGI), with adders 18 and 19, driver of color synchronization code 20, forming (L rover 22 codes test lines (FKIS), DAC 23, ale ent And 24, clock generator 25. Introduced FKSIGI 17, comparator 16, FKIS 22 and digital limiter 14 black level 1. 1 ill. 1C M M Ub x 00

Description

The invention relates to television technology and can be used in video recorders.

The purpose of the invention is to improve the accuracy of the correction by suppressing noise in the entire interval of the damping pulse, to obtain the standard rise time of the damping and synchronizing pulses, to improve the quality of compensation of precipitations and to regenerate the signals of the test lines when played back with non-nominal speeds of tape movement.

The drawing shows a structural electrical circuit of a digital corrector of temporal distortion of television signal signals of SECAM for video tape recorders.

The digital corrector of temporal distortions of the television signals of the SECAM system for video recorders contains an ADC 1, the output of which is connected via memory 2 to the input of the unit 3 for separating the luminance and chrominance signals. The first input of the A / D converter 1 is the video input of the digital temporal distortion corrector of the television signals of the SECAM system for video tape recorders; the second input of the A / D converter 1 is connected to the output of the 4 clock pulse generator. The output of the detector 5 fallouts through the shaper 6 pulses of deposition of the chrominance signal is connected to the control input of the first multiplexer 7. The first information input of the first multiplexer 7 is connected to the first output of the luminance and chrominance separation unit 3. The output of the first multiplexer 7 through the first 8 and second 9 delay lines connected in series is connected to its second information input.

The first input of the ADC 1 is combined with the input of the sync selector 10 and with the first input of the driver 11 pulses of 12.5 Hz. The first input of the addressing unit 12 is combined with the second input of the driver of 11 pulses 12j5 Hz, with the input of the driver of 4 clock pulses and connected to the output of the sync selector 10.

The second input of the ADC 1 is combined with the second input of the block 12 addressing. The output of block 12 addressing is connected to the second input of memory 2, and the first input of memory 2 is combined with the input of the imaging unit 6 pulses deposition of chrominance signals. The inputs of the first delay line 8 and the second delay line 9 are connected respectively to the first and second information inputs of the second multiplexer 13.

The control input of the second multiplexer 13 is connected to the output of the driver 11 pulses 12.5 Hz. The second output of the memory 2 is connected to the fifth input of the addressing unit 12. The second output of the luminance and chroma separation unit 3 is connected via a digital black level limiter 14 to the first information input of the third multiplexer 15 and to the first input of the comparator 16. The second information input of the third multiplexer 15 and the second input of the comparator 16 are combined and connected to the output of the clock 17 of the sync pulse pulses and damping pulses. The output of the comparator 16 is connected to the control input of the third multiplexer 15.

The first input of the first adder 18 is connected to the output of the second multiplexer 13, the second input is connected to the output of the third multiplexer 15. The first input of the second adder 10 is connected to the code of the color synchronization code generator 20, the second to the output of the first adder 18, and the output to the first information input of the fourth multiplexer 21. The second information input of the fourth multiplexer 21 is connected to the output

shaper 22 code test lines, and the output to the input of the DAC 23. The output of the DAC 23 is the output of the digital corrector of the temporal distortion of the television signals of the SECAM system for video recorders. The control input of the fourth multiplexer 21 is connected to the output of the element 24. The synchronizing generator 25 by the first and second outputs is connected to the third and fourth inputs of addressing unit 12, the third output to the third input of the imaging unit 11 pulses 12.5 Hz, the fourth and fifth outputs respectively - to

the first and second inputs of the imaging unit 20 of the color synchronization code, the sixth output to the third input of the comparator 16 and the first input of the imaging unit 17 of the sync pulse and damping pulse codes, the seventh output to the second input of the imaging unit 17 of the sync pulse and damping pulse code, the eighth output - the input of the shaper 22 of the test line code and to the first input of the AND 24 element. The second input of the AND 24 element is the input of the command Unspecified speed. The input of the detector of 5 fallouts is the input of the FM signal of the digital corrector of temporal distortions of the television signals of the SECAM theme for video tape recorders. The digital corrector of temporal distortion of television signals of the SECAM system for video recorders works as follows. The reproduced video recorder television signal of the SECAM system is fed to the input of the ADC 1, where it is converted into a binary parallel code and fed to the input of the charger 2. The process of disabling the signal in time and recording this signal into the charger 2 is performed synchronously and in phase with the reproduced signal. For this, the clock pulses T. {, which determine the moments of discretization of the television signal and record it in memory 2, are linked in frequency and phase to the reproduced signal. This is achieved by the fact that the 4-clock pulse shaper is controlled by the clock pulses TC from the output signal of the sync selector 10. The 4-shaper pulse generator is a frequency multiplier based on the pulse clock of the clock generator Tg, controlled by the synchro pulse pulses. .. For the time of the auto-tuning circuit is selected so that the system has time to monitor the time errors reproduced th signal. The digital signal is recorded in memory 2 according to the write addresses from the addressing unit. Address counters generate recording addresses at time points determined by clock pulses T. and preset the line and half-frame w pulses of a sequence of synchronizing pulses. As a result, the process of recording a digital signal into a memory device is synchronized with the input reproduced television signal and repeats the existing its time distortion. The signal is read from memory 2 in accordance with the addresses of reading, also coming from the block 12 addressing. However, the formation of read addresses occurs at times determined by the reference clock pulses Rj, and the preset of address counters is performed by horizontal and half-frame pulses of the reference sequence of clock pulses from the sync generator. As a result, temporal distortions are eliminated, and the digital signal at the output of memory 2 becomes stable over time. From the output of the charger 2, the signal goes to the block 3 for separating the luminance and chrominance signals. The luminance signal E is applied to a digital black level limiter 14, where pulsed and fluctuation noise is suppressed below the normalized black level, i.e. in the signal area where the clock pulses are transmitted. This operation is necessary, since the presence of random noise in the transmission area of a clock signal may cause a breakdown in the playback image. Digital black limiter 14 can be performed on a multiplexer. Code Words Corresponding to Signal Levels. Enter the black level that passes through the multiplexer to the output of the limiter. When a code combination corresponding to a level below the black level appears, a digital comparator is triggered, the multiplexer switches and the code corresponding to the selected black level is switched to the output of the limiter. In addition, at the same time, nonlinear distortions do not occur under the constraint, which are fundamentally inherent in all black level constraints. From the output of the digital black level limiter 14, the signal arrives at the first information input of the third multiplexer 15, where numerically the mixing of regenerated damping and synchronizing pulses is performed. Mixing is carried out in a cisme manner. In the intervals between damping pulses, the signal passes directly to the output of multiplexer 15. With the arrival of damping pulses, a comparator 16 is turned on, in which the signal combinations of the signal at the output of the digital black level limiter 14 and the sync pulse and damping pulses are compared word by word. If the signal level in the comparison zone is higher than the level of damping pulses arriving at the shaper 17 of the sync pulse and damping pulse codes, the comparator 16 is activated, the third multiplexer 15 switches and the damping and then synchronizing pulses pass to its output. Thus, non-additive mixing of the signal and damping pulses is achieved, which ensures the most correct introduction of damping pulses into the television signal. In the shaper 17 of the codes of sync pulses and damping pulses, the codes of damping and synchronizing pulses are generated using programmed counters or permanent memory devices. The formation is performed at time intervals determined by damping pulses and a clock signal coming from the synchronizer generator 25. Codes are formed in such a way as to ensure standard pulse rise times. In the first adder 18 of the brightness and chrominance signals, the components of luminance and chroma E are added. fallout and when playing at a nominal speed, the color signal E passes from the output of the block 3 separating the luminance and chroma signals through the first 7 and second 13 multiplexers to the first input ne Vågå adder 18, the luminance and chrominance signals. In the second adder 19, a code of color synchronization signals from a driver 20 of a code of color synchronization signals is entered into the signal. These signals are generated in nine lines in the field pulse quenching interval with the arrival of a 9H pulse from the clock generator 25. The sequence of red and blue row codes is determined by 7.8 kHz half line clock pulses from the -25 clock generator. From the output of the second adder 19, the signal passes through the fourth multi1 286 plexer 21 to the input of the DAC 23, from the output of which the analog television signal is fed to the output of the digital corrector of temporal distortions of the television signals of the SECAM system for video recorders. In the fourth multiplexer 21, the test string signals are mixed. The signal generation is carried out in the test pattern shaper 22, which is a read-only memory programmed with the test string signal codes. Codes are read only in the intervals of 17, 18, 330 and 331 lines in accordance with the pulses from the synchro-generator 25. When playing at a non-nominal speed, when the signals of the test lines are not reproduced, the corresponding command Unspecified speed enters And 24 and passes on its output is pulses of 17, 18, 330 and 331 lines, which switch the fourth multiplexer 21. In this case, the code of the test lines signals from the driver 22 of the test code passes to the output of the fourth multiplexer 21 lines, which replaces the test line signals missing in the reproduced signal. Fallout compensation is performed as follows. The reproduced FM signal is fed to a 5 dropout detector, the output of which produces pulses at the moments of the deposited signal. These pulses arrive at the third input, the input of the channel of the fall-out of memory 2, and record simultaneously with the television signal. Pulses are read simultaneously with reading the main signal. As a result, the deposition pulses appearing at the second output — the output of the channel of the ZU 2 fallout — are accurately phased with the instant of deposition in the digital stream at the output of the storage device and are somewhat ahead of the beginning because the signal delay in the ADC 1 is greater than the delay in the detector 5 steps. From the output of memory 2, the output pulses arrive at block 12 of addressing and change the readout addresses of the main signal, as a result of which, the output of memory 2 reads the signal without falling out. In this case, the readout addresses of the channel of the fall-out of memory 2 do not change. The algorithm for changing the addresses of the readout of the main signal may be different. In the simplest case, the read address is changed to the previous line. A line following the line with a dropout can be used. In a more complicated case, all the lines in memory 2 are analyzed, and the address of the nearest line that does not contain the fallout is selected. Thus, the compensation of the dropouts in the luminance signal is made without additional memory devices and with high quality due to the possibility of selecting the line without interrupting the memory array 2 of the memory 2. The specified process of compensation of the precipitations does not allow to eliminate the dropout in the chromaticity signal, since first, the phase of the color subcarrier in the storage signal may not coincide with the phase of the subcarrier in the row with a dropout; secondly, when working with SECAM signals, it is necessary to replace the chroma signal in the entire line with the affected one. For this, the chromaticity signal from the first output of the chromaticity block 3 times dividing the luminance and chromaticity signals is fed to the first information input of the first multiplexer 7, the second information input of which is fed to a signal delayed by two lines of the first and second lines 8 and 9 of the delay . In the line affected by the dropout, the first multiplexer 7 switches at the beginning of the line to the second information input the input of the delayed signal and passes to its output, the chrominance signal reaches the edge of the line. The switching of the first multiplexer 7 is effected by a pulse of about 64 ISS duration, which is generated in a row with the driver forming 6 pulses of the chroma signal. This shaper is a memory device whose number of cells is equal to the number of image lines recorded in the memory 2. The deposition of impulses is recorded simultaneously with the recording of the main signal in the memory 2. The address counter, included in the composition of the shaper 28, falls the lowercase sync pulses of the sequence T, and is preset by the half-frame pulses of that sequence. As a result, the impulse is written into a memory cell whose number corresponds to the line number of the falling recorded in the memory 2. The reading of the falling impulses is produced by the lower-order sync pulses of the sequence ... Due to this, the arrival of the lower-order sync impulse produces a dropout signal in the given line which at the same time begins to be read out from memory 2. In the presence of a former of 6 impulses of precipitation of a chromatic signal, an impulse is formed that extends to the next the horizontal sync pulse, which switches the first multiplexer 7 and substitute chrominance signal across line affected loss. When playing at a non-nominal tape speed, it becomes necessary to delay the chrominance signal by the time of one line. This delay is achieved by the second multiplexer 13, which switches to the output of the first delay line 8 at the time of one line by the Chroma Delay command. The process of compensating for depositions in the chroma signal is not disturbed. The Chroma Delay command is generated in the driver of 11 pulses of 12.5 Hz by comparing the phase of pulses of 12.5 Hz, made here from the reproduced signal, and similar pulses of 12.5 Hz, coming from the synchronous generator 25. The pulses of 12.5 Hz determine the number sex in a sequence of four fields SECAM. For example, in the fields of the first and second first frame these pulses have a logic level of 1, and in the fields of the first and second second frame - a logical level of O. If the levels of reproducible and reference pulses do not match 12.5 Hz, the Chroma Delay command is generated and the first the floor of the first frame to the first or second floor of the second frame, etc.

Claims (1)

Invention Formula Digital corrector of temporal distortions of television signals of the SECAM system for video tape recorders, containing serially connected analog-to-digital converter (ADC), storage device (charger) and block-separation of luminance and chromaticity signals, serially connected deposition detector, driver of chromaticity signal pulses, first multiplexer , the second multiplexer and the first adder, as well as the clock pulse shaper, the sync selector, the pulse shaper 12.5 Hz, the addressing unit, the shunt color synchronization code generator, sync generator, I element, first delay line, second delay line, third multiplexer, fourth multiplexer, digital-to-analog converter (D / A converter), second adder, the ADC input connected to the sync selector input and 12.5 Hz first pulse generator , the output of the sync selector is connected to the second input of the pulse generator 12.5 Hz, to the first input of the addressing unit and to the input of the clock pulse generator, the output of which is connected to the second input of the ADC and to the second input of the addr unit The output of the addressing unit is connected to the second memory input, the output of the detector detector is connected to the third memory input, the third and fourth inputs of the addressing unit are connected respectively to the first and second outputs of the synchronous generator, the first information input of the first multiplexer is connected to the first output of the luminance signal separation unit and chroma, the second information input is with the output of the second delay line, and the control input of the second multiplexer with the output of the pulse former 12.5 Hz, the third input of which is connected to the third sync generator output, the fourth and fifth outputs of which are connected respectively to the first and second inputs of the color synchronization code generator, the output of which is connected to the first input of the second adder, the input of the deposition detector and the input of the ADC are respectively the input of the FM signal and the video signal of the digital time distortion corrector Television: SECAM system signals for video recorders, characterized in that, in order to improve the correction accuracy by suppressing interference in the whole damping interval For example, obtaining the standard time for extinguishing damping and synchronizing pulses, improving the quality of compensating the steps and regenerating the test line signals during playback with non-nominal tape motion speeds, a synchro pulse and damping pulse shaper was inserted into it, a digital limiter code generator, a comparator, a digital limiter black level, the input of the digital black level limiter is connected to the second output of the luminance and chrominance separation unit, and the output is first m information input of the third multiplexer and the first input of the comparator, the second input of which is combined with the second information input of the third multiplexer and connected to the output of the sync pulse and damper codes, the first input of which is combined with the third input of the comparator and connected to the sixth output of the synchro generator, and the second the input is from the seventh sync generator, the output of the comparator is connected to the control input of the third multiplexer, the output of which is connected to the second input of the first adder The output of which is connected to the second input of the second adder, the output of which is connected to the first information input of the fourth multiplexer, the second information input of which is connected to the output of the test code generator, the output to the DAC input, and the control input to the output which is combined with the input of the test code generator and is connected to the eighth output of the synchronizing generator, the output of the first multiplexer is connected via the first delay line to the input of the second delay line, the input of the second The second delay line is combined with the second information input of the second multiplexer, the second memory output is connected to the fifth input of the addressing unit, the second input of the And element and the output of the DAC are respectively the input of the command. The nominal speed and output of the digital corrector of time signals of the SECAM television signals are 127742812. For video recorders.