RU2007894C1 - Device for separation of brightness and color signals in decoder of secam type - Google Patents

Abstract

FIELD: television. SUBSTANCE: device has unit 1 for separation of full color video signal into high- frequency and low-frequency constituents, five delay units 2, 6, 7, 9, 16, adder 3, phase detector 4, phase-modulated signal generator 5, two multipliers 8 and 11, low-pass filter 10 having tunable band of pass, generator 12 for generation of complex envelope of frequency-modulated signal, detector 13 for detection of complex envelope of frequency-modulated signal, signal differentiating unit 14, non-linear converter 15, subtraction unit 17. Device provides possibility for tracing separation of signal color and corresponding tracing rejection of brightness signal spectrum. Device also changes brightness range dynamically depending on range of jumps of color signal frequency. In addition negative feedback depending on frequency and control in feedback loop result in more effective separation of signals because the level of suppression of mutual interference between signals is achieved with less distortion of separated signals. EFFECT: decreased distortion of separated color and brightness signals. 1 dwg

Description

 The invention relates to television, in particular to the separation of luminance and color signals in the decoding device 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 decoding devices of the SECAM system.

 A device for separating luminance and color signals in decoding devices of the SECAM system is known.

 Containing a block for dividing the full color video signal (PCVS) into LF and HF components, adder, 1st, 2nd, 3rd, 4th, and 5th delay elements, phase detector, FM signal generator, 1st and 2nd multipliers, a low-pass filter with a controlled passband, a complex envelope detector of the FM signal, a signal differentiation unit, a nonlinear converter and a subtracter, the input of the PCVS to LF and HF components block being the input of the device, and the output of the LF component of the PCVS separation unit for LF and RF components through the 1st delay element n with the 1st input of the adder, the output of the RF component of the separation block of the PCVS into the LF and RF components is connected to the input of the phase detector, through the 5th delay element with the input of the reduced subtractor and through the 3rd delay element with the 1st input of 1- 1st multiplier, the output of the phase detector is connected to the input of the FM signal generator, the 1st and 2nd outputs of which are connected respectively to the 2nd input of the 1st multiplier and through the 2nd delay element of the 2nd multiplier, the output of the 1st multiplier through the 4th delay element and low pass filter with controlled passband not to the 1st input of the 2nd multiplier, the output of the circuit from the series-connected detector of the complex envelope of the FM signal, the differentiation unit and the nonlinear converter is connected to the control input of the low-pass filter, the output of the 2nd multiplier is connected to the output of the color signal of the device and to the input of the subtracted subtractor , the subtractor output is connected to the 2nd input of the adder, the output of which forms the output of the brightness signal of the device.

 The disadvantages of the known device are the presence of distortion of the luminance signal resulting from the notch of the spectrum in the area of deviation of the color subcarrier and the distortion of the color signal due to the superposition on the spectrum of the color signal of the spectrum of the luminance signal.

 The aim of the alleged invention is to reduce the aforementioned distortion of the luminance and color signals. This goal is achieved by the fact that, in order to reduce distortion of the luminance and color signals, an integrated FM envelope generator is additionally introduced, the input of which is connected to the output of the complex envelope of the FM signal detector, and the output is connected to the 3rd input of the 1st multiplier, the detector input of the complex envelope of the FM signal is connected to the output of the low-pass filter with a controlled passband.

 The drawing shows a structural diagram of the proposed device.

 The following notations are accepted: 1 - block for the separation of PCVS into LF and HF components, 2,6,7,9,16 - 1st, 2nd, 3rd, 4th and 5th delay elements, respectively 3 - adder, 4 - phase detector, 5 - FM signal generator, 8.11 - 1st and 2nd multipliers, 10 - low-pass filter with a controlled passband, 12 - generator of the complex envelope of the FM signal, 13 - detector of the complex envelope of the FM signal, 14 - signal differentiation unit, 15 - non-linear converter, 17 - subtractor.

 The proposed device for the separation of luminance and color signals in the decoding device of the SECAM system contains a block for the separation of PCVS into LF and HF components (1), 1st, 2nd, 3rd, 4th and 5th delay elements (2, 6 , 7, 9, 16), adder (3), phase detector (4), FM signal generator (5), 1st and 2nd multipliers (8.11), low-pass filter with controlled passband (10), generator complex envelope of the FM signal (12), a detector of the complex envelope of the FM signal (13), a signal differentiation unit (14), a nonlinear converter (15), a subtractor (17). The output of the PCVS separation unit for LF and HF components forms the input of the device, and the output of the LF component of the PCVS separation unit for LF and HF components through the 1st delay element (2) is connected to the 1st input of the adder (3). 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), through the 5th delay element (16) with the input of the reduced subtractor (17) and through the 3rd delay element (7) with the 1st input of the 1st multiplier (8). The output of the phase detector (4) 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 (8) and through the 2nd delay element (6) 2 th multiplier (11). The output of the 1st multiplier through the 4th delay element (9) and the low-pass filter with a controlled passband (10) is connected to the 1st input of the 2nd multiplier (11). The input of the generator of the complex envelope of the FM signal (12) is connected to the output of the detector of the complex envelope of the FM signal (13), and the output is connected to the 3rd input of the 1st multiplier (8). The input of the detector of the complex envelope of the FM signal (13) is connected to the output of the low-pass filter with a controlled passband (10). The circuit output from the series-connected detector of the complex envelope of the FM signal (13), the differentiation unit (14) and the nonlinear converter (15) is connected to the control input of the low-pass filter (10). The output of the 2nd multiplier (11) is connected to the output of the color signal of the device and to the input of the subtracted subtractor (17). The subtractor output is connected to the 2nd input of the adder (3), the output of which forms the output of the brightness signal of the device.

 The device operates as follows.

 In block (1), the spectrum of the input signal is divided into the low-frequency part located in band 0. . 3 MHz and the HF part of the signal in band 3.. . 6 MHz The low-frequency part of the signal is fed to the first input of the adder (3) 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 (3).

 The sequentially connected PD (4) and FMG (5) together act as the ideal limiter of the RF part of the PCVS. At the outputs of the FMG (5), complex mutually conjugate signals of the color subcarrier W (t) and W * (t) are formed.

 In the multiplier (8), complex multiplication of the RF part of the PCVS, the 1st complex signal and the frequency feedback signal is performed. As a result of this multiplication, a complex envelope of the FM signal is formed with reduced deviation due to negative frequency feedback.

 In the negative frequency feedback loop, frequency detection of the complex envelope in BH (13) and frequency modulation in the FMG (12) with deviation opposite in sign of the deviation of the color signal contained in the PCVS are performed sequentially.

 In the low-pass filter (10), the bandwidth of this signal is limited. In the multiplier (11), the signal spectrum is transferred back, as a result of which we obtain a color subcarrier signal 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. This signal is subtracted from the signal of the RF component of the PCVS in the subtractor (17), 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 filter (10) is band-controlled; its cutoff frequency depends on the magnitude of the jumps in the color subcarrier frequency. This dependence is provided by a circuit of a series-connected frequency detector of the complex envelope of the FM signal (13), a signal differentiation unit (14), and a nonlinear converter (15).

 The parameters of these devices and the low-pass filter (10) are selected so that the frequency band of the low-pass filter at small differences, for example, less than 0.25 the magnitude of the brightness signal, is small (for example, equal to 0.3 MHz). At maximum differences, it can correspond to the notch band of modern decoders of the SECAM system.

 For intermediate values of the amplitude of the differences, the law of change of the band depending on the signal level is determined by the amplitude characteristic of the nonlinear converter (15).

 The presence of a tracking signal of a color signal and, accordingly, a tracking notch of the spectrum of the luminance signal simultaneously with a dynamic change in its band depending on the amplitude of the jumps in the frequency of the color signal in combination with frequency feedback and control of the passband of the low-pass filter in the feedback loop, makes the separation more efficient, than in known devices, since the same degree of suppression of mutual interference is accompanied by less distortion of the shared signals.

 (56) Copyright certificate of the USSR N 1800657, cl. H 04 H 9/72, 1980.

Claims (1)

 DEVICE FOR SEPARATION OF BRIGHTNESS AND COLOR SIGNALS IN THE SECAM SYSTEM DECODER, which contains series-connected unit for separating the full color video signal (PCVS) into low-frequency (LF) and high-frequency (HF) components, the first delay line and the adder, the output of which is the output of the device's brightness signal, connected in series a phase detector, the input of which is connected to the second output of the PCVS separation unit for LF and HF components, a phase-modulated (FM) signal generator, a second delay line and the first multiply a device whose output is the output of the color signal of the device, connected in series with a third delay line, the input of which is connected to the input of the phase detector, a second multiplier, the second input of which is connected to the second output of the FM signal generator, the fourth delay line and a low-pass filter (LPF) with controlled a passband, the output of which is connected to the second input of the first multiplier, a complex envelope detector, a differentiation unit and a nonlinear converter, the output of which is connected in series the second is connected to the control input of the LPF with a controlled passband and connected in series to the fifth delay line, the input of which is connected to the input of the third delay line, and a subtraction unit, the second input of which is connected to the output of the first multiplier, and the output is connected to the second input of the adder, characterized in that, in order to reduce distortion of the luminance and color signals, a complex envelope generator of a frequency-modulated signal is introduced, included between the output of the complex envelope detector and the third WTO input th multiplier, and LPF output with controllable bandwidth connected to the input of the detector integrated chastotnomodulirovannogo envelope signal.