RU1811027C - Digital device for separating chrome and luminous signals in secam decoder - Google Patents

Abstract

The invention relates to television and can be used in video monitoring devices of analog-to-digital uplift studio complexes of television broadcasting and in television broadcast receivers. The purpose of the invention is to reduce distortion of luminance and color signals. The device comprises an analog-to-digital converter 1, a unit for dividing the full color video signal into low-frequency and high-frequency components 2, three delay blocks 3, 6, and 7, adder 4. two digital-to-analog converters 5 and 13, a subtractor 8, two following band-pass filters 9 and 15, frequency detector 10, signal differentiation unit 11, two non-linear converters 12 and 14. 1-2-3-4-5, - 2-6-7-8-4, 6-9-8, 10-15-13 , - 10-11-12-9, 11-14-15. 1 ill.

Description

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The invention relates to television and can be used in analogue-digital hardware-studio television broadcast complexes and in television broadcast receivers.

The purpose of the invention is to reduce distortion of luminance and color signals.

Structural diagram of the proposed device is shown in the drawing; 1 - analog-to-digital converter (ADC); 2 - a block for dividing the PCVS into LF and HF components; 3-1th delay block; 4 - adder; 5 - 1st DAC; 6, 7 - 2nd and 3rd delay blocks, respectively; 8 - subtractor; 9, 1.5 - 1st and 2nd following bandpass filters; 10 - frequency detector (BH); 11 - signal differentiation unit (BDS); 12, 14 - 1st and 2nd nonlinear converters (NP); 13 - 2nd DAC.

The proposed device for separating the luminance and color signals in the decoder of the SECAM system contains ADC 1, a block for dividing the PCVS into LF and HF components of the 2.1 3rd, 2nd 6 and 3rd 7 delay blocks, the adder 4, 1- 5th and 2nd DACs 13, subtractor 8, 1st 9th and 2nd 15th following bandpass filters, frequency detector 10, signal differentiation unit 11, 1st and 2nd nonlinear converters 12, 14,

The input of the device through ADC 1 is connected to the input of the unit. The PCVS is divided into LF and HF components 2, the first output of which is the output of the H H component of the PCVS, and the 2nd output is the output of the HF component.

The 1st output of the PCVS separation unit for LF and HF components 2 through the 1st delay unit 3 is connected to the 1st input of the adder 4, the output of which through the 1st DAC 5 is connected to the output of the device brightness signal.

The 2nd output of the PCVS separation unit for the LF and HF components 2 is connected to the inputs of the 2nd delay unit 6 and the frequency detector 10 ,.

The outputs of the 3rd delay unit 6 are connected to the inputs of the 3rd delay unit 7 and the 1st servo bandpass filter 9, the outputs of which are connected respectively to the inputs of the subtracted and subtracted subtractor 8.

The output of the frequency detector 10 is connected to the 1st control input of the 1st follow-up band-pass filter 9 and through a chain of series-connected signal differentiation unit 11 and the 1st non-linear converter 12 to the 2nd control input of the 1st follow-up filter band-pass filter 9. The output of the subtractor 8 is connected to the 2nd input of the adder 4.

The 2nd servo bandpass filter 15 is connected between the output of the 2nd delay unit

ki 6 and the input of the 2nd DAC 13, the output of which is the output of the color signal of the device. A 2nd non-linear converter 14 is connected between the output of the signal differentiation unit 11 and the 2nd control input of the second next bandpass filter. The 15.1st control input of which is connected to the output of the frequency detector. The device operates as follows.

The full color video signal is digitized by the ADC 1.

Using low-pass filter 16 from the spectrum of PCVS

5, its low frequency part is allocated in the 0 ... 3 MHz band. In the subtractor 18, the low-frequency part is subtracted from the input PCVS, and the high-frequency part of the signal in the 3 ... 6 MHz band is formed at the output of the subtractor. The low-frequency part of the signal goes to the first

0, the input of adder 4 is added to the RF 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 adder 4.

The 5HF coupled PCVS is supplied simultaneously to the input of the 2nd delay unit 3 and to the input of the frequency detector 10.

At the output of the frequency detector, a signal is generated that characterizes the frequency of the FM0 color signal, which is fed to the 1st control inputs of the 1st and 2nd SPF 9 and 15, through which their spectral frequency is controlled.

In the 1st SPF from the HF component of the PCVS

5, a fairly narrow band portion of the spectrum is allocated; concentrated in the region of the instantaneous frequency of the color subcarrier, and this contributes to its noise tolerance. The frequency band of the 1st SPF depends on

0 range of color subcarrier frequency jumps. This dependency is provided. a chain of sequentially connected signal differentiation unit 11 and the 1st non-linear converter 12. The parameters of these devices and the 1st SPF 9 are chosen such that the frequency band of the 1st SPF at small differences, for example, less than 0.25 of the magnitude of the brightness signal, is small (for example, equal to 0.3 MHz). At maximum drops, it can correspond to the rezion band of modern decoders of the SECAM system.

For intermediate values of the amplitude of the differences, the law of band variation depending on the signal level is determined by the amplitude characteristic of the 1st non-linear converter 12,

Claims (1)

In the 2nd SPF, a rather narrow-band part of the spectrum is concentrated from the RF component of the PCVS, concentrated in the region of the instantaneous frequency of the color subcarrier, and this contributes to its noise-tolerant separation. The frequency band of the 2nd SPF can depend on the magnitude of the frequency jumps of the color subcarrier, for example, according to the law, at which the threshold level of the differentiated signal of frequency jumps (at which interference is mainly transmitted to the color channel, the bandwidth is very small, for example, 100 kHz and when the frequency jumps exceed the threshold level, the band is selected to the maximum and decreases as it tends to the maximum attainable level of jumps. Delay blocks 3,6,7 are used to coordinate signal delays in parallel 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 amplitude of the color signal, in combination with the use of a change in the frequency band of the color channel, consistent with frequency jumps color subcarrier, allows to make the separation more efficient than in known devices, since the same degree of suppression of mutual interference is achieved at the cost of less distortion separating their signals. SUMMARY A digital device for separating luminance and color signals in a SECAM system decoder, comprising an analog-to-digital converter connected in series, the input of which is an input of a full color video signal, a block for dividing the full color video signal into low-frequency and high-frequency components, the first delay unit, the adder, and the first digital-to-analog converter, the output of which is the output of the brightness signal of the device, the second delay unit is connected in series, the third ok delay and a subtraction unit, the output of which is connected to the second input of the adder, and the second input is connected through the signal bypass of the first servo bandpass filter to the output of the second delay unit, a frequency detector connected in series, the input of which is connected to the input of the second delay unit and the second output of the separation unit full color video signal for low-frequency and high-frequency components, a differentiation unit and a first non-linear converter, the output of which is connected to the first control input of the first about the next bandpass filter, the second control input of which is connected to the output of the frequency detector, and the second digital-to-analog converter, the output of which is the output of the color signal of the device, which means that, in order to reduce distortion of the brightness and color signals, a second a following bandpass filter, the signal input of which is connected to the output of the second delay unit, and the output is connected to the input of the second digital-to-tax converter, and the second nonlinear converter, the input of which is connected to progress of differentiating unit, and an output connected to a first control input of the second servo bandpass filter, a second control input coupled to an output of the frequency detector.