JPH04890A - Color subcarrier generator - Google Patents

Abstract

PURPOSE:To cope with a change in a sampling point and a change in the sampling data of a burst part by separating a burst signal from inputted digital composite video signals and detecting the edge pulse of the burst signal, and then, resetting a counter which divides a inputted clock by using the edge pulse. CONSTITUTION:A line alternate signal generator 13 produces a line alternate signal C which is alternately produced at every horizontal line at certain timing of the horizontal line other than burst parts of inputted digital composite video signals. A burst edge pulse detector 14 detects the rising edge pulse of the second and after second pulses except the first pulse. Moreover, burst edge pulses D are produced at every line by gating the rising edge pulse by using the line alternate signal C at every line. Then color subcarriers E are produced by resetting the counter which divides the sampling clock (4 fsc) of a color subcarrier generator 15 by using the burst edge pulses D.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color subcarrier generation device for equipment handling digital composite video signals.

Conventional technology A conventional color subcarrier generation device will be explained with reference to FIG.

FIG. 7 is a block diagram of a conventional color subcarrier generator. In the figure, 71 is a horizontal synchronizing signal generator that generates a burst gate signal from an input digital composite video signal, and 72 is a horizontal synchronizing signal generator that generates a burst gate signal from an input digital composite video signal.
An 8-bit conhaler 73- compares the input digital composite video signal with the first burst data;
Bit comparator 74 is an 8-bit comparator that compares the input digital composite video signal and the third burst data; 75 is an 8-bit comparator that compares the input digital composite video signal and the fourth burst data; 76 77 is a second delay device that delays input data by 2 clocks. 78 is a third delay device that delays input data by 3 clocks. 79 is a delay device that delays input data by 4 clocks.
A fourth delay device 80 that delays the clock is a four-man AND gate that performs the AND of the outputs of the first to fourth delay devices 76 to 78 to obtain a burst detection signal.
Composite video signal sampling clock (4
The color subcarrier generator generates a color subcarrier from fsc), a burst gate signal, and a burst detection signal.

The operation of the color subcarrier generator configured as described above will be described below. As shown in FIG. 8, the horizontal synchronizing signal generator 71 generates a burst gate signal a that becomes high during the burst portion of the input digital composite video signal.
generate. The 8-bit comparators 72-75, the delay devices 76-79, and the 4-person gate 80 compare the input digital composite video signal with the first to fourth burst data and output a burst detection signal. Here, the first to fourth burst data are four consecutive sampling data of the burst portion of the input digital composite video signal as shown in FIG. When four consecutive sampling data of the input digital composite video signal match the first to fourth burst data, the burst detection signal output from the four-person AND gate 80 goes high.

The color subcarrier generator 81 generates a color subcarrier by resetting a counter that divides the sampling clock (4fsc) of the input digital composite video signal with a signal gated by the burst detection signal a by the burst gate signal a. do.

Problems to be Solved by the Invention However, in the above conventional configuration, the input digital
When the sampling point of the composite video signal changes, the sampling data of the burst portion also changes, so there is a problem that the first to fourth burst data must be reset in order to detect a burst. Was.

The present invention solves the above-mentioned conventional problems, and uses a relatively simple circuit to generate color subcarriers that can cope with changes in the sampling point of the input digital composite video signal and the sampling data in the burst portion. The purpose is to provide equipment.

Means for Solving the Problems To achieve this object, the color subcarrier generation device of the present invention comprises horizontal synchronization signal generation means for creating a burst gate signal from an input digital composite video signal;
burst signal separation means for separating a burst signal from the input digital composite video signal; burst edge pulse detection means for detecting a burst edge pulse from the burst gate signal and the burst signal; and a color subcarrier generation means for generating a color subcarrier by resetting a counter that divides a signal sampling clock (4fsc) by the burst edge pulse, and the color subcarrier of the present invention The generator includes: horizontal synchronizing signal generating means for creating a burst gate signal from an input digital composite video signal; burst signal separating means for separating a burst signal from the input digital composite video signal;・Line alternate signal generating means for generating a line alternate signal that alternates for each horizontal line at a certain timing of the horizontal line of the video signal, and generating a burst signal every other line from the burst gate signal, the burst signal and the line alternate signal. burst edge pulse detection means for detecting an edge pulse; and color subcarrier generation means for generating a color subcarrier by resetting a counter that divides the sampling clock (4fsc) of the input digital fist composite video signal using the burst edge pulse. a color subcarrier edge pulse detection means for detecting a color subcarrier edge pulse from the burst gate signal and the color subcarrier; detecting a phase of the color subcarrier from the burst signal and the color subcarrier edge pulse; and line alternating reset signal generating means for generating a line alternating reset signal for resetting the line alternating signal generating means.

Operation The present invention has the above-described configuration, so that even when the sampling point of the input digital composite video signal changes and the sampling data of the burst portion changes,
The burst signal separation means separates the burst signal from the input digital composite video signal, the burst edge pulse detection means detects the edge pulse of the burst signal, and the counter that divides the input clock (4fsc) is reset by the edge pulse to normalize the signal. Obtain the color subcarrier of .

EXAMPLE Hereinafter, a first example of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of a color subcarrier generator in the PAL system and the PALM system. In FIG. 1, 11 is a horizontal synchronizing signal generator that generates a burst gate signal A from an input digital composite video signal, 12 is a burst signal separator that separates a burst signal B from an input digital composite video signal, and 13 14 is a line alternate signal generator that generates a line alternate signal C that alternates for each horizontal line at a certain timing of the horizontal line of the input digital composite video signal; 14 is a burst gate signal A, a burst signal B, and a line alternate signal C; 15 is a sampling clock (4fsc) of the input digital composite video signal;
), a color subcarrier generator generates a color subcarrier E by resetting a counter that divides the frequency by the burst edge response D, and 16 detects a color subcarrier edge pulse F from the burst gate signal A and the color subcarrier E. A color subcarrier edge pulse detector 17 detects the phase of the color subcarrier from the node signal B and the color subcarrier edge pulse F, and generates a line alternate reset signal G for resetting the line alternate signal generator 13. This is a line alternator reset signal generator.

The operation of the color subcarrier generating device of this embodiment configured as described above will be described below. As shown in Figure 2, in the PAL and PALM systems, in order to obtain a color subcarrier from burst edge information, the burst edge pulses must be applied to either the odd or even lines, that is, the burst edge pulses must be applied every other line. The counter that divides the sampling clock (4fsc) of the input digital composite video signal must be reset to obtain the color subcarrier. As shown in FIG. 3, in the horizontal synchronizing signal generator 11, the input digital
A burst gate signal A is output from the composite video signal during the burst portion of the signal. The burst signal separator 12 outputs a burst signal B containing information of the burst signal portion by comparing the input digital composite video signal with a certain fixed value. The line alternate signal generator 13 generates a line alternate signal C that alternates for each horizontal line at a certain timing of a horizontal line that is not a burst part of the input digital composite Φ video signal. As shown in FIG. 4, the burst edge pulse detector 14 gates only a portion of the burst signal B using the burst gate signal A, and the partial pulse of the burst signal B (
A&B). The first pulse from the partial pulses (A&B) to obtain accurate burst edge information of burst signal B.
The rising edge pulses of the second and subsequent pulses excluding the second pulse are detected. Furthermore, this rising edge pulse is gated by the line alternate signal C to generate a burst edge pulse D for each line. In the color subcarrier seed generator 15, a counter that divides the sampling clock (4fsc) of the input digital composite video signal is reset by the burst edge pulse D to generate a color subcarrier E. The color subcarrier edge pulse detector 16 generates partial pulses (A&E) in which the color subcarrier E is gated by the burst gate signal A. In order to obtain accurate color subcarrier edge information of color subcarrier E, the first pulse is removed from the partial pulse (A&E) and the second pulse is
The rising edge portion of the pulse after the pulse is detected, and a color subcarrier edge pulse F is generated. line alternator
The triset signal generator 17 detects the phase of the color subcarrier E from the burst signal B and the color subcarrier edge pulse F,
Reset line alternate signal C.

Either the odd line or the even line, i.e.
In the conventional example, the phase of the color subcarrier E could not be uniquely determined because the counter was reset every other line, but in this embodiment, by resetting this line alternate signal C, the phase of the color subcarrier E can be determined. can be uniquely determined.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows a block diagram of a color subcarrier generator in the NTSC system. In FIG. 5, 51 is a horizontal synchronizing signal generator that generates a burst gate signal A from an input digital composite video signal; 52 is a burst signal separator that separates a burst signal B from the input digital composite video signal;
53 is a burst edge pulse detector that detects a burst edge pulse D from the burst gate signal A and burst signal B; 54 is a burst edge pulse detector that divides the sampling clock (4fsc) of the input digital composite video signal; This is a color subcarrier generator that is reset by a pulse D to generate a color subcarrier E.

The operation of the color subcarrier generating device of this embodiment configured as described above will be described below. As shown in Figure 6, in the NTSC system, in order to obtain the color subcarrier from burst edge information, a counter is used to divide the sampling clock (4fsc) of the input digital composite video signal by the burst edge pulse of each line. Just reset it. The color subcarrier generation device of this embodiment corresponds to the first embodiment of the present invention, that is, from the color subcarrier generation device in the PAL system and the PALM system, to the line alternate signal generator, the color subcarrier edge pulse detector, and the line alternate signal generator. It is equivalent to removing the triset signal generator and the rest of the parts work exactly the same.

Effects of the Invention As described above, according to this embodiment, there is provided a burst signal separating means for separating a burst signal from an input digital composite video signal, and a burst edge 7 for detecting a burst edge pulse from a burst gate signal and a burst signal. Equipped with a frequency loss detector to prevent the sampling point of the input digital composite video signal from changing.
Even when the sampling data in the east part changes, the noise signal separator
)・Separates the burst signal from the video signal, detects accurate noise east edge information, i.e., burst error, from the burst signal with a stored edge pulse detector, and samples the input digital composite video signal. A regular color subcarrier can be obtained by resetting a counter that divides the clock (4fsc) with a burst edge pulse.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a color subcarrier generator in a first embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the embodiment, and FIGS. 3 and 4 are signal diagrams in the same embodiment. Timing chart, FIG. 5 is a block diagram of a color subcarrier generation device according to a second embodiment of the present invention, FIG. 6 is a waveform diagram for explaining the same embodiment, and FIG. 7 is a conventional color subcarrier generation device. FIG. 8 is a timing chart for explaining the operation of a conventional color subcarrier generator. 11.51...Horizontal synchronization signal generator, 12.52...
- Burst signal separator, 13... Line alternate signal generator, 14.53... Burst edge pulse detector, 15.54... Color subcarrier generator, 16... Color printing carrier wave edge pulse detector, 17
...Line alternator reset signal generator. Name of agent: Patent attorney Shigetaka Awano (1 person) Fig. 2 filJ peep 1 line hearth) Signal b) @z line burst signal Cedar Odd line burst edge U No. L; -' 1 I class

Claims (1)

[Scope of Claims] (1) horizontal synchronization signal generation means for creating a burst gate signal from an input digital composite video signal; burst signal separation means for separating a burst signal from the input digital composite video signal; burst edge pulse detection means for detecting a burst edge pulse from the burst gate signal and the burst signal; and a counter that divides the sampling clock (4fsc) of the input digital composite video signal by resetting it with the burst edge pulse. A color subcarrier generation device comprising a color subcarrier generation means for generating a color subcarrier. (2) The burst edge pulse detection means according to claim 1 outputs an edge pulse of one clock width of the second and subsequent pulses from a signal having a plurality of pulses in a line obtained by gating the burst signal with a burst gate signal. Color subcarrier generator. (3) horizontal synchronization signal generation means for creating a burst gate signal from the input digital composite video signal; burst signal separation means for separating the burst signal from the input digital composite video signal; line alternate signal generation means for generating a line alternate signal that alternates for each horizontal line at a certain timing of a horizontal line of a video signal; burst edge pulse detection means for detecting a pulse; and color subcarrier generation means for generating a color subcarrier by resetting a counter that divides the sampling clock (4fsc) of the input digital composite video signal using the burst edge pulse. and a color subcarrier edge pulse detection means for detecting a color subcarrier edge pulse from the burst gate signal and the color subcarrier; detecting a phase of the color subcarrier from the burst signal and the color subcarrier edge pulse. and line alternate reset signal generating means for generating a line alternate reset signal for resetting the line alternate signal generating means. (4) The burst edge pulse detection means according to claim 3 generates edge pulses of one clock width of the second and subsequent pulses from a signal having a plurality of pulses in a line obtained by gating the burst signal with a burst gate signal. , and a color subcarrier generation device that outputs the edge pulse every other line by gating with a line alternate signal. (5) The color subcarrier edge pulse detection means according to claim 3 is characterized in that the color subcarrier is gated with a burst gate signal and includes a plurality of pulses in a signal having a one clock width edge pulse of the second and subsequent pulses. A color subcarrier generator that outputs . (8) The line alternate reset signal generating means according to claim 3 detects the phase of the color subcarrier from the burst signal and the color subcarrier edge pulse, and generates the line alternate signal so that the phase of the color subcarrier is always constant. Color subcarrier generator to reset.