SU1478382A1 - Method for synchronization of channels of tv receivers - Google Patents

Abstract

The invention relates to television technology. The purpose of the invention is to improve the accuracy of control. The method of controlling the synchronization channels of television receivers consists in supplying frame and horizontal synchronization signals to the input of the synchronization channel. In order to determine whether the line or frame synchronization is violated, two time intervals are formed: the first, equal to an even number of periods of the input frame signal, and the second, equal to an even number of periods of the output frame signal. Next, count the number of output horizontal pulses during the first time interval and the number of input horizontal pulses during the second time interval. By comparing the obtained numbers with the given ones, the performance of the channel is determined. The device that implements the method contains r-1, controlled channel 2 synchronization, two dividers 3 and 7 frequencies, two counters 4 and 8, two decoders 5 and 10, two D-flip-flops 6 and 9. 2 Il.

Description

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The invention relates to a television technology, in particular to the monitoring of synchronization channels of television receivers, and may find application in the radio electronic industry.

The purpose of the invention is to improve the accuracy of control.

Figure 1 shows an electrical block diagram of a device implementing the proposed method; 2 shows waveform diagrams.

The device contains a generator 1, controlled channel 2 synchronization, the first frequency divider 3, the first counter 4, the first decoder 5, the first D-flip-flop 6, the second divider 7 frequency, the second counter 8, the second D-flip-flop 9 and the second decoder 10.

The method is as follows.

In modern television receivers, interlaced scanning is used, due to which the number of lines in the first and second half-frames is different. To eliminate this ambiguity, it is necessary to form a time interval equal in duration to an even number of periods of the frame signal, i.e. a whole number of frames.

By counting the number of horizontal pulses at the output of the synchronization channel during an even number of periods of the output frame signal, it is possible to determine the frequency ratio of these two signals and, therefore, monitor the timing characteristics of the synchronization channel. But in the event of a channel failure, it is impossible to determine what line or frame synchronization is broken.

To eliminate this drawback, two time intervals are formed: the first, equal to an even number of periods of the input frame signal, and the second, equal to an even number of periods of the output frame signal.

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Next, count the number of output horizontal pulses during the first time interval and the number of input horizontal pulses during the second time interval, comparing the obtained numbers with the given ones, determine the operability of the channel.

In this case, the mismatch of the number of pulses specified in the first time interval means the breakdown of horizontal synchronization, and the mismatch of the number of pulses specified in the second time interval means the failure of frame synchronization.

The device that implements the method, W works as follows. From the generator 1 to the monitored channel 2, mixed frame and horizontal sync signals are supplied. The synchronization channel has two outputs: 15 turns: the output of the horizontal signals, denoted by the SI (FIG. 2, b) t, and the output of the personnel signals, denoted by the CR (FIG. 2, e).

The divider 3 is used to form the 20th and the first time interval, for which frame clock pulses are applied to its input from the generator 1 (Fig.). Divider 3 should have a division factor of 25 2n, where n is the number of periods of the personnel signal during the first time interval.

Thus, at the output of the divider

3 (Fig. 2.8), a signal in the form of a 30 square wave with a period equal in duration to the first two time intervals is formed. This signal is then fed to the input R0 (set to zero) of the counter 4, to the counter

This input +1 is fed from the horizontal pulses from the SI output of channel 2.

.When there is an inlet R0 counter

The 4 logical 1 signals are reset to the zero state, and

40 in the presence of the input R 0 logical O counts the number of pulses arriving at the counting input +1. Thus, pulse counting is performed during the first time interval.

To compare the number of pulses with a given one, a decoder 5 is used, to the inputs of which signals are output from the bits of the counter

4 when the number of pulses coincides with that given at the output of the decoder 5 (Fig. 2, d), a logical 1 signal is generated, otherwise a logical O.

The signal from the output of the decoder 5 is fed to the input of the D-flip-flop 6, and the input from the C-flip-flop 6 is fed to the signal from the divider 3, as a result of which information is written to the trigger

55

a signal at the output of the decoder 5 at the time of termination of the first time interval.

The rest of the device operates in the same way, except that the divider 7 is supplied with a signal from the output of the channel 2 channel, resulting in the formation of a second time interval (fig.zh), which is fed to the input R 0 of the counter 8, as well as to the input C- trigger 9. The counting input of the counter 8 (Fig. 2, e) is fed by synchronizing horizontal pulses from the generator 1, and to the input of the D-trigger 9 a signal from the decoder 10 (Fig. 2), the inputs of which are connected to the outputs of the bits of the counter 8.

Thus, the presence of logical units at the outputs of flip-flops 6 and 9 (f1gg2, l) indicates the operability of channel 2, the presence of a logical O signal at the output of flip-flop 6 indicates a breakdown of horizontal synchronization, and the presence of a logical O at the trigger output 9

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five

0

five

indicates a breakdown of frame synchronization.

Claims (1)

Invention Formula The method of controlling synchronization channels of television receivers, which consists in supplying frame and line synchronization signals to the synchronization channel input, which is characterized by the fact that, in order to increase the control accuracy, two time intervals are formed, the first being equal in duration to an even number periods of the input frame signal, the second is equal in length to an even number of periods of the output frame signal, and both time intervals are formed by dividing the input and output frequencies, respectively frame signals, count the number of output horizontal pulses during the first interval, the number of input horizontal pulses during the second time interval, and compare the obtained values with the specified Input frame sienna. . entrance belitel 3  Vvorenno interval. Output divider 5 output lowercase. Output C U nala 2 Sienol on course } encoder 5 Sianal but exit trieero6 Output frame signal Output KCKanap time interval lunge dividers 7 Vnodochktchika input line & C yen l Outlet decoder 1О