RU2012163C1 - Digital device for separation of color and brightness signals in secam decoders - Google Patents

Abstract

FIELD: television equipment. SUBSTANCE: device has analog-to-digital converter 1, unit 2 for separation of integral color video signal into high-frequency and low-frequency constituents, two delay units 3, 6, adder 4, two digital-to-analog converters 5, 12, subtraction unit 7, high-frequency distortion correction unit 8, two multipliers 9, 11, adjustable band-pass filter 10, frequency-modulated signal generator 13 having phase automatic frequency control, integral frequency- modulated signal generator 14, high-frequency distortion filter 15, signal differentiating circuit 16, control signal generator 17, integral signal frequency detector 18. Device provides tracing selection of color signal along with frequency feedback, which decreases deviation of source signal, as well as tracing rejection of spectrum of color signal along with dynamic alterations in its band which depend on size of jumps of color signal amplitude. In addition device provides frequency shift of high-frequency constituent of integral video signal. EFFECT: decreased distortion of color and brightness signal during their separation. 1 dwg

Description

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

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

 A device for separating luminance and color signals in the decoders of the SECAM system (ed. St. N 1172082, class H 04 N 11/18, published 07.08.85), which contains serially connected first delay unit, the input of which is connected to the input of the correction unit high-frequency predistortions (EHF), and a subtractor and a series-connected generator of a frequency-modulated (FM) signal with phase-locked loop (PLL) and a high-frequency predistortion filter (HPF).

 A disadvantage of the known device is 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 distortion of the color signal due to the superposition of the spectrum of the luminance signal on its spectrum.

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

 This is achieved by the fact that an analog-to-digital converter (ADC) is added to the device, the input of which is the input of a full color video signal (PCVS), a PCVS separation unit for low-frequency (LF) and high-frequency (HF) components, a second delay unit, an adder, and a second the input of which is connected to the output of the subtractor, and the first digital-to-analog converter (DAC), the output of which is the output of the brightness signal, the first multiplier connected in series, the input of which is connected to the output of the RFI filter, tunable a band-pass filter, a second multiplier and a second digital-to-analog converter (DAC), the output of which is an output of a color signal, a frequency detector of a complex signal, the input of which is connected to the output of a tunable band-pass filter, and a complex FM signal generator, the first and second outputs of which are connected respectively to the second inputs of the first and second multipliers, the output of which is also connected to the second input of the subtractor, and the differentiation unit connected in series, the path of which is connected to the output of the frequency detector of the complex signal, and the non-linear converter, the output of which is connected to the control input of the tunable bandpass filter, the second output of the PCVS to low-frequency and high-frequency signal separation unit is connected to the input of the EHF unit, the output of which is connected to the input of the FM signal generator with the PLL .

 The drawing shows a structural diagram of the proposed device.

 It contains an ADC 1, a block for the separation of PCVS into LF and HF components of the 2.2nd 3 and 1st 6 delay blocks (BZ), the adder 4, 1st and 2nd DACs 5, 12, the subtractor 7, the EHP unit 8, 1st and 2nd multipliers 9, 11. PPF 10, FM signal generator with PLL 13, complex FM signal generator 14, high-pass filter 15, BDS 16, control signal shaper 17 and BH KS 18.

 The input of the PCVS separation unit for LF and HF components 2 is connected through the ADC 1 to the input of the device, the 1st LF output of the PCVS separation unit for LF and HF components through the 2nd БЗ 3 is connected to the 1st input of the adder 4. The output of the adder through 1 the 5th DAC 5 is connected to the output of the device brightness signal, the 2nd (HF) output of the PCVS separation unit for the low and high frequency components is connected to the inputs of the EHF unit 8 and the 1st BZ 6. Between the output of the EHF unit 8 and the output of the device color signal a chain of series-connected FM signal generator with PLL 13, HPV filter 15, the 1st multiplies Yelaya 9, PPF 10, 2nd multiplier 11 and 2nd DAC 12. The output of the 1st БЗ 6 is connected to the input of the decreasing subtractor 7, the output of which is connected to the 2nd input of the adder 4. The output of the 2nd multiplier 11 is connected to input deductible subtractor. The output of the PPF 10 is connected to the input of the series of BH KS 18, BDS 16 and the driver of the control signal 17. The output of the nonlinear converter is connected to the control input of the PPF 10. The output of the BH KS 18 through the generator of the complex FM signal 14 is connected to the 2nd input 1- of the second multiplier 9, the 2nd output of the complex FM signal generator 14 is connected to the 2nd input of the 2nd multiplier 11.

 The device operates as follows.

 The full color video signal using the ADC 1 is converted to digital form.

 Using the block for separation of PCVS into LF and HF components 1 from the spectrum of PCVS, its LF part in band 0 is extracted. . 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 adder 4, is 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 adder 4, which is converted into an analog form using the 1st DAC 5.

 The RF component of the PCVS is fed through the EHF unit 8 to the FM signal generator with a PLL 13, the output of which generates a signal with completely eliminated spurious amplitude modulation, which occurs due to the overlap of the color signal with RF interference from the luminance signal.

 The signal from the output of the FM signal generator from the PLL 13 is converted using the high-pass filter 15 into a standard color signal, in which noise from the luminance signal is largely suppressed.

 The generator of the complex FM signal 14 in the frequency feedback loop is controlled by the signal from the output of the BH KS 18 and generates a complex signal with a frequency deviation opposite in sign of the deviation of the color signal contained in the PCVS. Multiplication in the multiplier 9 of this signal by the RF component of the PCVS reduces the frequency deviation in accordance with the principle of using frequency feedback. The received signal is limited by the band in PPF 10.

 The cutoff frequency of the PPF depends on the magnitude of the jumps in the frequency of the color subcarrier. This dependence is provided by a chain of series-connected BH KS 18, BDS 16 and the shaper of the control signal 17 in the feedback loop. The parameters of these devices and PPF 10 are selected so that the frequency band of PPF at small differences, for example, less than 0.25 of the magnitude of the luminance 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 driver of the control signal 17.

 In the 2nd multiplier 11, the signal spectrum is transferred back, as a result of which we obtain a color subcarrier signal in which processing is equivalent to the extraction of this signal by a follow-up filter, which reduces the level of noise 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 7, 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. Using the 2nd DAC 12, the color signal is converted to analog form.

 The presence of a tracking signal of the color signal in combination with frequency feedback, which reduces the deviation of the original signal and, accordingly, the tracking rejection of the spectrum of the luminance signal simultaneously with the dynamic change of its band depending on the amplitude of the jumps in the color signal amplitude, as well as the transfer of the RF component of the PCVS in frequency, allows separation is more effective than in known devices, since the same degree of mutual interference suppression is achieved at the cost of less distortion of the shared signals .

Claims (1)

 A DIGITAL BRIGHTNESS AND COLOR SIGNALING DEVICE DEVICE IN THE SECAM SYSTEM DECODER, containing the first delay block in series, the input of which is connected to the input of the high-frequency predistortion correction unit (EHF), and the subtracter and the series-connected generator of a frequency-modulated (FM) signal with a phase-locked loop PLL) and a high-frequency predistortion filter (high-pass filter), characterized in that, in order to reduce distortion of luminance and color signals, an analog-to-digital converter (ADC) is introduced ), the input of which is the input of the full color video signal (PCVS), a block for dividing the PCVS into low-frequency (LF) and high-frequency (HF) components, a second delay unit, an adder, the second input of which is connected to the output of the subtractor, and the first digital-to-analog converter (DAC), the output of which is the output of the brightness signal, the first multiplier connected in series, the input of which is connected to the output of the high-pass filter, a tunable band-pass filter, a second multiplier and a second digital-to-analog converter (DAC), the output of which Horn is a color signal output, a frequency detector of a complex signal, the input of which is connected to the output of a tunable bandpass filter, and a complex FM signal generator, the first and second outputs of which are connected respectively to the second inputs of the first and second multipliers, the output of which is also connected to the second the input of the subtractor, and the differentiation unit connected in series, the input of which is connected to the output of the frequency detector of the complex signal, and the driver signal, the output of which is connected to the control input of the tunable band-pass filter, the second output of the PCVS separation unit for the low- and high-frequency components is connected to the input of the high-frequency filter block, the output of which is connected to the input of the FM signal generator with the PLL.