JPH0217770A - System for transmitting synchronization of television signal - Google Patents

Abstract

PURPOSE:To decrease a ratio of the section of a synchronizing signal to one horizontal scanning section and to increase the ratio of the section of a video signal by separating a horizontal synchronizing signal from a burst signal, and performing synchronism extraction by using the above separation. CONSTITUTION:A composite synchronizing signal 16 is time-multiplexed on the video signal 8 at a multiplex circuit 9 in a transmission part 5, and a television signal 10 is generated. The video signal 8 is the one in which a time base-compressed chrominance signal and luminance signal are time base- multiplexed, and it is inputted to a synchronism extraction circuit 13 in a reception part 12 after passing a transmission path 11. Here, the signal is inputted directly to a burst signal processing part 15, however, the signal is inputted to a notch filter 16 having a zero point at a burst signal frequency, and the output signal 17 of the filter is inputted to a horizontal synchronizing signal processing part 14. In such a way, it is possible to perform synchronous transmission by the horizontal synchronizing signal and the burst signal in the section of the synchronizing signal narrower than a conventional one, and to widen the section to be allocated to the video signal.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a television signal synchronous transmission system.

(Prior Art) In order to extract one phase of the horizontal scanning frequency from a television signal, it has been common practice to multiplex a horizontal synchronizing signal and a burst signal into a television signal. As is well known, horizontal synchronization signals can detect phase errors over a wide range of phase differences, but their accuracy suffers.On the other hand, with burst signals, the detection range of phase errors is limited. This is because they have mutually contradictory characteristics: narrow but high accuracy. FIG. 2 shows an example of a conventional signal waveform in one horizontal scanning section of a television signal. - The horizontal scanning section 1 is composed of a horizontal synchronizing signal section 2 including a horizontal synchronizing signal, a burst signal section 3 including a burst signal, and a video signal section 4. FIG. 3 shows a configuration diagram of a transmission device using a conventional television signal synchronous transmission system. In the transmitter 5, the horizontal synchronizing signal 6. The burst signal 7I video signal 8 is time-axis multiplexed in a multiplexing circuit 9 to create a television signal 10. After passing through the transmission path 11, this signal is inputted to the horizontal synchronization signal processing section 14 and burst signal processing section 15 in the synchronization extraction circuit 13 of the reception section 12, respectively.
By the way, as a video signal transmission method, the color signal is compressed on the time axis, and the color signal is compressed on the time axis, and this is used as the luminance. The so-called TCI (Time Compress) is inserted into the horizontal blanking section of the signal and transmitted.
A system called ed integration) transmission system has come into use, especially in the transmission of high-definition television signals. In the case of this method, - Since the synchronization signals of nine color signals and three kinds of luminance signals are time-axis multiplexed in the horizontal scanning section, - The ratio of the section occupied by the synchronization signal to the horizontal scanning section must be made as small as possible. Therefore, if separate sections are allocated to the horizontal synchronization signal and the burst signal as in the conventional example, the proportion of the section occupied by the synchronization signal to one horizontal scanning section becomes large, making it difficult to multiplex the color signals. There have been cases where it has become difficult to do so. This problem can be solved by compressing the time axis of the luminance signal to some extent, but this will complicate the node-ware.Another problem is that the horizontal synchronization signal and the burst signal will be assigned separate sections. In the conventional method, the ratio of the video signal section to the -horizontal scanning section cannot be made sufficiently large, and the problem arises that it becomes difficult to insert a color signal, especially in the TCI transmission method. SUMMARY OF THE INVENTION An object of the present invention is to solve these problems by reducing the ratio of the synchronizing signal section to the horizontal scanning section.

This invention performs transmission using a composite synchronization signal consisting of a horizontal synchronization signal and a multi-pass 4g signal, and on the receiving side uses a notch filter with the burst signal frequency as its zero point to separate the horizontal synchronization signal and burst signal. and performing synchronization extraction using each of them. Here, the composite synchronization signal is composed of a plurality of synchronization signal sections having predetermined constant values that are different from each other, and at least one of them is It is assumed that a sine wave whose frequency is predetermined as the first signal frequency is superimposed in the synchronization signal section.

In the following explanation, the synchronization signal section in which a sine wave is superimposed will be referred to as a burst section.

(Operation) When the composite synchronization signal is input to a notch filter whose zero point is the strike signal frequency on the receiving side, the sine wave is removed in the output section corresponding to the burst section, and a constant value before the sine wave is output. , the constant value is also output for other synchronization signal sections.Since these constant values are determined to be different values in advance, the output signal waveform corresponding to the composite synchronization signal has a change point of the value compared to the conventional horizontal synchronization signal. This is a waveform that can be detected over a wide phase difference using the same method as the signal detection method.Therefore, this waveform is regarded as a horizontal synchronization signal, and the conventional processing for horizontal voice 1st period 4M is performed in the synchronization extraction circuit. In addition, the sine wave in the burst period can be processed in the same way as a conventional burst signal.In addition, the sine wave in the burst period can be processed as both a horizontal synchronization signal and a burst signal. Because of this, the length of the synchronization period can be made shorter than in the conventional method of separately allocating the horizontal synchronization signal period and the burst signal period.

(Embodiment) FIG. 1 shows a configuration diagram of a transmission device using a television signal synchronous transmission system according to an embodiment of the present invention. Transmission section 5/
/c, the composite synchronization signal 16 and the video signal 8 are time-axis multiplexed in a multiplexing circuit 9 to create a television signal 10. Here, in the case of the above-mentioned TCI transmission system, the video signal 8 becomes a signal in which the time axis is compressed and the colorimetric signal and the luminance signal are time axis multiplexed. After passing through the transmission line 11, this signal is input to the synchronous axis output circuit 13 in the receiving section 12.

Here, this signal is directly input to the burst signal processing unit 15 as in the conventional example, but to the horizontal synchronization signal processing unit, this signal is input to a notch filter 16 having a zero point at the burst signal frequency. input and its output signal 17 is input. FIG. 4 shows a signal waveform in one horizontal scanning section of a television signal according to an embodiment of the present invention.

Composite synchronization signal section 18 consists of three synchronization signal sections 24.25
．． 26, and in this embodiment, the synchronization signal section 25
The sine wave is multiplied by 7i to form a burst section, and the constant value of the sync signal section 24 is smaller than the average value of the sync signal section 25, and the constant value of the sync signal section 26 is smaller than the average value of the sync signal section 25. This is a general rule. FIG. 5 shows an example of the configuration of a notch filter. An input signal 18 of a 0-notch filter is input to a delay circuit 19, and the sum of its output signal 20 and input signal 18 is created by an adder 21, and a notch filter output signal 17 is generated. becomes. Here, if the delay time of the delay circuit 19 is set to a time that is % of a predetermined burst signal period, it becomes possible to remove the sine wave in the burst period. FIG. 6(a) shows a composite synchronizing signal waveform 22 which is an input signal of the notch filter, and FIG. 6(b) shows an output signal waveform 23 of the notch filter corresponding to the composite synchronizing signal.

The difference between a constant output value corresponding to a burst interval in the output signal waveform 23 and a constant value corresponding to the interval immediately before the burst interval, or a constant output value corresponding to the burst interval and a constant value corresponding to the interval immediately after the burst interval. Detection of a change point corresponding to a difference from a constant output value can be easily performed by comparing with an appropriate reference value commonly used in conventional horizontal synchronization signal processing units. In this configuration, there are 2 points of change.
There are 2 locations, so you can use only one of them, but 2
By detecting these points and checking the intervals between the detection points, more reliable horizontal synchronization separation can be achieved.

Note that this configuration is based on a so-called positive synchronization method in which the signal level range of the composite synchronization signal and the signal level range of the video signal overlap. In such a case, the approximate position of the horizontal synchronization signal can be predicted from the detection point of the vertical synchronization key signal or 7-frame pulse, etc., and the horizontal scanning synchronization that is known in advance, and the malfunction of the synchronization extraction circuit due to the video signal waveform can be detected. Although prevention has conventionally been performed, it goes without saying that the synchronization extraction circuit of this configuration also performs such an operation.

〔Effect of the invention〕

According to this F3AK, synchronous transmission using a horizontal synchronization signal and a burst signal can be transmitted in a narrower synchronization signal interval than before,
As a result, it is possible to make the section allocated to the video signal wider than before. This is T.C.
This is particularly effective in the I transmission system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a transmission device using a synchronous transmission system for television signals according to an embodiment of the present invention, FIG. 2 is a conventional signal waveform in one horizontal scanning section of a television signal, and FIG. 4 is a block diagram of a transmission device using a conventional television signal synchronous transmission system, FIG. 4 is a signal waveform in one horizontal scanning section of a television evening signal according to an embodiment of the present invention, and FIG. 5 is a diagram of a notch filter. A configuration diagram, FIG. 6 shows a composite synchronization signal waveform and its corresponding waveform according to an embodiment of the present invention),
This is the output waveform of the filter. 1...-Horizontal scanning section, 18... Composite synchronizing signal section, 24... Periodic signal section, 25... Synchronizing signal section (
Burst section), 26... Synchronization signal section, 4... Video signal section, 5... Transmitting section, 12... Receiving section, 13
... Synchronization extraction circuit, 16... Notch filter.

Claims (1)

[Claims] One horizontal scanning section is divided into a composite synchronizing signal section and a video signal section in the transmitting section, and for the composite synchronizing signal section,
It is divided into a plurality of synchronization signal sections having predetermined constant values that are different from each other, and at least one of the divided synchronization signal sections has a sine wave whose frequency is predetermined as a burst signal frequency. The synchronization extraction circuit in the receiving section uses the signal of the synchronization signal section on which the sine wave is superimposed of the composite synchronization signal as a burst signal, and converts the composite synchronization signal into a notch whose zero point is a predetermined burst signal frequency. A television signal synchronization transmission system characterized by inputting the signal to a filter and extracting synchronization using the output signal as a horizontal synchronization signal.