RU1800657C - Device for separating chrominance and brightness signals in secam decoder - Google Patents

Abstract

Usage: in the CCU of analog-to-digital apparat-studio complexes of television broadcasting and in television broadcasting receivers, in the detectors of the SECAM system of which the brightness and color signals are separated. The essence of the invention. shadows: a device for reducing distortion of luminance and color signals contains a block 1 for dividing the full color video signal, a low-pass filter 2, six delay lines (3,4,8,9,11,17), two subtractors 5.18, a phase detector 6, a generator 7 phase-modulated signal, two multipliers 10, 13, a low-pass filter 12 with a controlled passband, a frequency detector 14 of the complex envelope of the frequency-modulated signal, a signal differentiation unit 15, a programmable read-only memory unit 16 adder 19. The presence of the following is highlighted respectively, and chrominance servo rejection spectrum luminance signal simultaneously with its dynamic izmo- neniem strip depending from - Range frequency jumps .pozvol chrominance signal is to make the separation more effective. 1 ill. n

Description

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The invention relates to television; it can be used in the VCU of analog-to-digital hardware-studio complexes of television broadcasting and in. television broadcasting receivers;

The aim of the invention is to reduce the aforementioned distortion of the horn and color signals.

. The drawing shows a structural diagram of the proposed device,

1 - block separation PCVS on the LF and HF leaving,

2-2 and low-pass filters,:,. . 3,8,9,11,17,4 - 1-, 2-, 3-, 4-, 5- and 6-delay lines, 18, 5 - 1st and 2nd subtracters, 6 - phase detector, 7 - FM signal generator, 13, 10 - 1st and 2nd multipliers, 2 - T - and low-pass filters with controlled bandwidth,

14 - frequency detector of the complex envelope of the FM signal.

15 - signal differentiation unit,

16 - programmable read-only memory block, 19 t-adder.

The proposed device for separating luminance and color signals in the decoder of the SECAM system contains a second low-pass filter 2, a first 3, a second 8, a third 9, a fourth 11, a fifth 17 and a sixth 4 delay lines, the first 18 and second 5 subtractors, a phase detector 6, a generator 7 FM signal, the first 13m second 10 multipliers, the first low-pass filter 12, the adder 19, the frequency detector 14 of the complex envelope of the FM signal, the signal differentiation unit 15, and the programmable read-only memory block 16. The inputs of the second low-pass filter 2 and the sixth delay line 4 are interconnected and form the input of the device. The output of the second low-pass filter is connected to the input of the subtracted second subtractor 5 and

through the first delay line 3 with the first input of the adder 19. The output of the sixth line

the delay is connected to the input of the decreasing second subtractor, the output of which is connected to the input of the phase detector 6, with the input of the decreasing first subtractor 18 through the fifth delay line 17 and through the third delay line 9 with the first input of the second multiplier 10. The output of the phase detector is connected to the input of the generator 7 FM signal, the first and second outputs of which are connected respectively to the second input of the second multiplier 10 and through the second delay line to the second input of the first multiplier 13. The output of the second multiplier through the series tionary connected to the fourth delay line 11 and the first LPF 12 is connected to the second input of the first multiplier and via a series connection frequency detector

14 of the complex envelope of the FM signal, the differentiation unit 15 and the programmable read-only memory unit 16 are connected to the control input of the first low-pass filter, the output of which is connected to the input of the subtracted second subtractor. The output of the second subtractor is connected to the output of the color signal of the device (C) and to the second input of the adder, the output of which forms the output of the brightness signal of the device (Y).

The device operates as follows.

Using the low-pass filter 2, the low-frequency part in the 0 ... 3 MHz band is extracted from the PCVS spectrum. In subtractor 5, the bass part is subtracted from

of the input PCVS, and the RF part of the signal in the band 3 ... 6 MHz is formed at the output of the subtractor. The low-frequency part of the signal is supplied to the first input of the adder 19 and added to the high-frequency part of the signal, in which the spectrum of the color subcarrier is cut, and the resulting luminance signal is generated at the output of the adder 19.

The series-connected phase detector 6 and generator 7 together act as the ideal limiter of the RF part of the signal and the outputs of the generator 7. complex interconnected signals of the color subcarrier W (t) nW (t) are formed. . . In block 10, complex multiplication of the RF part of the signal and the first complex signal of the color subcarrier W (t) is performed. As a result of multiplication, the spectrum transfer of the HF part is achieved.

a signal such that at each time instant, the instantaneous frequency of the FM-scanned color contained in this signal is transferred to zero frequency.

In the first low-pass filter 12, the bandwidth of this signal is limited. In the multiplier 13, the reverse takes place

signal spectrum transfer, resulting in

we get a color subcarrier signal,

in which the processing is carried out, it is equivalent to isolating this signal by a follow-up filter, which allows to reduce the level of interference that penetrates into it from the luminance signal. This signal is subtracted from the signal of the RF component of PCVS in the subtractor 18.6, as a result of which the RF component of the luminance signal processed

so that it is implemented dynamically

rejection of color subcarrier interference.

The first low-pass filter 12 is controlled

on a strip, and its cutoff frequency depends on

the azmaha of frequency jumps in the color sub-tray. This dependence is provided by a chain of successively connected frequency detectors of the complex envelope of the FM signal, signal differentiation unit 15, and programmable read-only memory unit 16.

The parameters of these devices and the low-pass filter 12 are selected so that the low-pass filter low-frequency band, for example, less than 0.25 of the magnitude of the brightness signal, is small (for example, a frequency of 0.3 MHz). At maximum differences, it can correspond to the cut-off band of modern SECAM system decoders.

For intermediate values of the amplitude of the differences, the law of change of the band is determined by the nonlinear dependence recorded in the programmable read-only memory block 16.

The presence of the following extraction of the color signal and, accordingly, the following re-registration of the spectrum of the brightness signal simultaneously with the dynamic change of its band depending on the amplitude of the jumps in the frequency of the color signal allows us to make the separation more efficient than in known devices, because at the same time, the same degree of suppression of mutual interference is accompanied by less distortion of the separated signals.

Claims (1)

SUMMARY OF THE INVENTION A device for separating luminance and chrominance signals in a SECAM system decoder, comprising a unit for dividing a full color video signal (PCVS) into low-frequency (LF) and high-frequency (HF) deliveries, the input of which is the input of the PCVS, and the adder, the output of which is the output luminance signal, characterized in that, in order to reduce distortion of luminance and color signals, the first delay line is inserted, connected between the first output of the PCVS separation unit for LF and HF components and the first adder input, after edovatelno connected to the phase detector, the input of which is connected to the second output of the separation unit PTSVS at LF and HF components, phase manipulated (FM) signal generator, a second delay line and the first peremnozhitelk output of which is the output of the color signal, connected in series with a third delay line, the input of which is connected to the input of the phase detector, the second multiplier, the second input of which is connected to the second output an FM signal generator, a fourth delay line and a first low-pass filter, the output of which is connected to the second input of the first multiplier, a frequency detector of the complex envelope of the frequency-modulated (FM) signal, the input of which is connected to the output of the second multiplier, a signal differentiation unit and a block programmable read-only memory, the output of which is connected to the second input of the first low-pass filter, and serially connected five delay lines, the input of which is connected to the input t etey delay line, and a first subtractor, a second input coupled to an output of the first poremnozhitel and an output - to a second input of the adder, wherein the separation unit PTSVS at LF and HF components are formed as a second low-pass filter, the input of which is the input of the frequency separation unit, and the output is the first output of the PCVS separation unit for low and high frequency components and is connected to the first input of the second subtractor, the second, the input of which is through the sixth delay line is connected to the input of the second low-pass filter, and the output of the second subtractor is the second output of the separation block of the PCVS into LF and HF components.