RU2014751C1 - Device for separating color and brightness signals in secam system decoder - Google Patents

Abstract

FIELD: TV engineering. SUBSTANCE: device has unit 1 for separating total color videosignal to low-frequency and high-frequency components, five delay units 2,6,8,10,18, adder 3, phase detector 4, phase-modulated signal detector 5, three multipliers 7,17 and 19, band-pass-controlled lower frequency two filters 11 and 16, frequency-modulated signal complex envelope frequency detector 12, differentiating unit 13, two control signal formers 14 and 15, subtracter 19. Application of different laws of control of band-passes of tracking filters in brightness and color channels permits to determine optimal laws for changing band-passes in these channels depending on peak-to-peak jumps of frequency. EFFECT: improved quality separation of color and brightness signals. 1 dwg

Description

 The invention relates to television, in particular to the separation of luminance and color signals in the decoder of the SECAM system, and can be used in VCU analog-digital hardware-studio complexes of television broadcasting and in television broadcast receivers.

 The device is intended for separation of luminance and color signals in the SECAM system decoder.

 A device for separating luminance and color signals in decoders of the SECAM system (prototype).

 The known device contains a first low-pass filter (LPF) with a controlled passband and a series-connected subtractor and adder, the output of which is the output of the brightness signal.

 A disadvantage of the known device is the presence of distortion of the luminance and color signals.

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

 This is achieved by the fact that a series-connected unit for separating the full color video signal (PCVS) into low-frequency (LF) and high-frequency (HF) components, the input of which is the input of the PCVS, and the first delay unit, the output of which is connected to the second input of the adder, a series-connected phase detector, a phase-modulated (FM) signal generator, a second delay unit and a first multiplier, the output of which is a color signal output, a third delay unit connected in series ki, the second multiplier, the second input of which is connected to the second output of the FM signal generator, and the fourth delay unit, the output of which is connected to the information input of the first low-pass filter with a controlled passband, the output of which is connected to the second input of the first multiplier, connected in series to the complex envelope frequency detector frequency-modulated (FM) signal, the input of which is connected to the output of the second multiplier, the differentiation unit and the first non-linear converter, the output of which is connected to the control the input of the first low-pass filter with a controlled passband, the second non-linear converter connected in series, the input of which is connected to the input of the first non-linear converter, the second low-pass filter with a controlled passband, the information input of which is connected to the output of the fourth delay unit, and the third multiplier, the second input of which is connected to the output of the second delay unit, and the output with the first input of the subtractor, and the fifth delay unit, the input of which is connected to the inputs of the third delay unit, phase detector and torym exit separation unit PTSVS at LF and HF components, and the output - is connected to the second input of the subtractor.

 The drawing shows a structural diagram of the proposed device.

 The proposed device contains a block 1 for dividing the PCVS into LF and HF components, an adder of the 3rd, 1st and 2nd low-pass filters 11, 16 with a controlled bandwidth, the 1st, 2nd, 3rd, 4th and 5th delay blocks 2, 6, 8, 10, 18, subtractor 19, phase detector 4, FM signal generator 5, 1, 2, and 3 multipliers 7, 9, 17, frequency detector 12 of the complex envelope FM -signal, block 13 differentiation, the 1st and 2nd nonlinear converters (14, 15). The input of block 1 of the separation of PCVS to LF and HF components forms the input of the device. The output of the low-frequency component of the separation unit PCVS for low and high-frequency components through the 1st block 2 delay and the adder 3 is connected to the output of the brightness signal of the device. The output of the RF component of the PCVS separation unit for LF and RF components is connected to the input of the phase detector 4, to the input of the diminishing subtractor 19 through the 5th delay unit 18 and through the 3rd delay unit 8 with the 1st input of the 1st multiplier 9 The output of the phase detector is connected to the input of the FM signal generator 5, the 1st and 2nd outputs of which are connected respectively to the 2nd input of the 1st multiplier and through the 2nd delay unit 6 to the 2nd input of the 2nd multiplier 7, the output of the 1st multiplier through the 4th delay unit 10 and the 1st low-pass filter 11 with a controlled passband is connected to the 1st input an ode of the 2nd multiplier and through a series-connected frequency detector of the complex envelope of the FM signal 12, the differentiation unit 13 and the 1st non-linear converter 14 are connected to the control input of the 1st low-pass filter. The input of the 2nd nonlinear converter 15 is connected to the output of the differentiation unit 13, the output of the 2nd nonlinear converter is connected to the control input of the 2nd low-pass filter 16. The input of the 2nd low-pass filter is connected to the output of the 4th delay block 10, the output of the 2nd low-pass filter connected to the 2nd input of the 3rd multiplier 17, the 1st input of which is connected to the output of the 2nd delay unit 6. The output of the 3rd multiplier is connected to the input of the subtracted subtractor (19), the output of which is connected to the 2nd input of the adder 3. The output of the color signal of the device is the output of the 2nd multiplier 7.

 The device operates as follows.

 Using the separation unit for PCVS into LF and HF components, the spectrum of PCVS is divided into the LF part in the band 0 ... 3 MHz and the RF part in the band 3 ... 6 MHz. The low-frequency part of the signal is fed to the first input of adder 3 through the 1st delay unit 2 and is added to the high-frequency part of the signal, in which the spectrum of the color subcarrier is rejected, and the resulting luminance signal is generated at the output of adder 3.

 Serially connected PD 4 and FMG 5 together act as an ideal limiter of the RF part of the signal, and complex mutually conjugate signals of the color subcarrier W (t) and W * (t) are formed at the outputs of FMG 5.

 In the multiplier 9, complex multiplication of the RF part of the signal and the 1st complex signal of the color subcarrier (W (t) is performed. As a result of multiplication, the spectrum of the RF part of the signal is transferred such that at each moment of time the instantaneous frequency of the color FM signal contained in this signal, is transferred to zero frequency.

 In the 1st low-pass filter 11 and in the 2nd low-pass filter 16 with a controlled passband, the spectrum bandwidth of this signal is limited. In the multiplier 7, the signal spectrum is transferred back, as a result of which a color subcarrier signal is obtained, in which the processing is equivalent to the extraction of this signal by a follow-up filter, which reduces the level of interference that penetrates into it from the luminance signal. The signal from the output of the 2nd low-pass filter is subtracted from the signal of the RF component of the PCVS in the subtractor 19, as a result of which the RF component of the luminance signal is formed, processed so that it dynamically rejects interference from the color subcarrier.

 The low-pass filters 11 and 16 are band-controlled, and their amplitude-frequency characteristics depend on the magnitude of the jumps in the frequency of the color subcarrier. These dependencies are provided by a circuit of a series-connected frequency detector of the complex envelope of the FM signal 12, a signal differentiation unit 13, and non-linear converters 14 and 15.

 The parameters of the 1st low-pass filter 11 and the 1st NP 14 are selected so that the frequency band of the low-pass filter changes so that the derivative of the frequency jump changes so that the color channel band at all jump levels is consistent with the optimum color for the channel.

 The parameters of the 2nd low-pass filter 16 and the 2nd NP 15 are chosen so that the frequency band of the low-pass filter so changes with the level of the derivative of the frequency jump so that the band of the brightness channel at low levels of jumps is minimal and expands with increasing jumps.

 Using various laws of controlling the passband of the tracking filters in the luminance and color channels allows us to establish the optimal laws of changing the passband in these channels with a change in the amplitude of the frequency jumps and thereby improve the quality of separation of the luminance and color signals, which leads to a decrease in the distortion of these signals.

Claims (1)

 DEVICE FOR SEPARATION OF BRIGHTNESS AND COLOR SIGNALS IN SECAM SYSTEM DECODER, containing the first low-pass filter (LPF) with a controlled passband and series-connected subtractor and adder, the output of which is the output of the luminance signal, characterized in that, in order to reduce distortion of the luminance and color signals , a series-connected unit for separating the full color video signal (PCVS) into low-frequency (LF) and high-frequency (HF) components, the input of which is the input of the PCVS and the first block behind holders, the output of which is connected to the second input of the adder, a phase detector, a phase-modulated (FM) signal generator, a second delay unit and a first multiplier, the output of which is a color signal output, a third delay unit, a second multiplier, the second input of which is connected to the second output of the FM signal generator and the fourth delay unit, the output of which is connected to the information input of the first low-pass filter with a controlled passband, the output of which is connected to the second m input of the first multiplier, connected in series to the frequency detector of the complex envelope of the frequency-modulated signal, the input of which is connected to the output of the second multiplier, a differentiation unit and a first driver of the control signal, the output of which is connected to the control input of the first low-pass filter with a controlled passband, sequentially connected to the second driver of the control signal, the input of which is connected to the input of the first driver of the control signal, the second low-pass filter with a controlled band pr lowering, the information input of which is connected to the output of the fourth delay unit and the third multiplier, the second input of which is connected to the output of the second delay unit, and the output is connected to the first input of the subtractor, and the fifth delay unit, the input of which is connected to the inputs of the third delay unit, phase detector and the second output of the PCVS separation unit for LF and HF components, and the output is connected to the second input of the subtractor.