RU2014755C1 - Digital device for separating brightness and color signals in secam system decoder - Google Patents

Abstract

FIELD: TV engineering. SUBSTANCE: device has analog-to-digital converter 1, unit 2 for separating total color videosignal to low-frequency and high-frequency components, two delay units 3,6, adder 4, two digital-to-analog converters 5,8, subtracter 7, two multipliers 9, 11, tuneable band-pass filter 10, complex frequency-modulated signal generator 12, differentiating unit 13, control signal former 14, complex signal frequency detector 15. Availability of tracking separation of color signal combined with frequency feedback, which reduces deviation of initial signal and availability of tracking rejection of color signal spectrum simultaneously with dynamic change in brightness band depending on peak-to-peak amplitude of brightness signal, allows to separate signals of color and brightness without distortion. High-frequency component of total color videosignal is transferred to the frequency. EFFECT: excluded distortion. 1 dwg

Description

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

 A device for separating luminance and color signals in the decoding devices of the SECAM system, comprising a series-connected first delay unit (BZ) and a subtractor, a tunable band-pass filter and a generator of a complex frequency-modulated (FM) signal.

 The disadvantages of the known device are the presence of distortion of the luminance signal resulting from the notch of the spectrum in the region 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. The goal is achieved by the fact that the device is connected to a series-connected ADC, the input of which is the input of a full color video signal (PCVS), a block for dividing the PCVS into low-frequency and high-frequency components, a second knowledge base, an adder, the second input of which is connected to the output of the subtractor and the DAC, the output which is the output of the luminance signal, the first multiplier, the first input of which is connected to the input of the first BZ and the second output of the PCVS separation unit for the LF and HF components, the second DAC, the output of which is the output of the color signal, the second multiplier, p the first input of which is connected to the first output of the complex FM signal generator, the second input is connected via a tunable bandpass filter to the output of the first multiplier, and the output is connected to the second input of the subtractor and the input of the second DAC, and the frequency detector is connected in series, the input of which is connected to the second input of the second a multiplier, a differentiation unit and a driver of the control signal, the output of which is connected to the second input of the tunable band-pass filter, the input of the complex FM signal generator is connected to the output private detector, and the second output with the second input of the first multiplier.

 The structural diagram of the proposed device is shown in the drawing, where 1 is an ADC, 2 is a block for the separation of PCVS into LF and HF components, 3 and 6 are the first and second BZ, 4 is the adder, 5 and 8 are the first and second DACs, 7 is a subtractor, 9 and 11 are the first and second multipliers, 10 is a tunable band-pass filter, 12 is a complex FM signal generator, 13 is a signal differentiation unit, 14 is a control signal shaper, 15 is a complex signal frequency detector.

 The input of the device through the ADC 1 is connected to the input of the block 2 for the separation of the PCVS into the LF and HF components, the first output of which is the output of the LF component, and the second output is the output of the HF component. The first output of the block 2 for dividing the PCVS into LF and HF components through a chain of series-connected first BZ 3, adder 4 and first DAC 5 is connected to the output of the brightness signal of the device. The second output of the block 2 for dividing the PCVS into LF and HF components through the second БЗ 6 is connected to the first input of the subtractor 7, the output of which is connected to the second input of the adder 4. A chain of series-connected first multiplier 9, tunable band-pass filter 10, second multiplier 11 and the second DAC 8 is connected between the second output of the block 2 for dividing the PCVS into LF and HF components and the output of the color signal of the device. The output of the filter 10 is connected to the input of the frequency detector 15 of the complex signal, the output of which through the generator 12 of the complex FM signal is connected to the second input of the first multiplier 9. The first output of the generator 12 of the complex FM signal is connected to the first input of the second multiplier 11. A circuit input from series-connected unit 13 of the differentiation of the signal and the driver 14 is connected to the output of the frequency detector 15 of the complex signal, and the output to the control input of the band-pass filter 10. In the digital implementation of the processing device and the signal in it is, for example, in an eight-digit digital code.

 The device operates as follows.

 The full color video signal using the ADC 1 is converted to digital form. Using block 2, the separation of the PCVS into the LF and HF components from the spectrum of the PCVS distinguishes its LF part in the band 0 ... 3 MHz and the HF part in the band 3 ... 6 MHz The low-frequency part of the signal is fed to the first input of adder 4 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 adder 4. The RF component of the PCVS is fed to the input of the first multiplier 9, where the complex multiplication of the RF part of the PCVS and the frequency feedback signal is performed.

 The mode of operation of the device depends on the choice of the resting frequency of the generator 12 of the integrated FM signal. If it is equal to the resting frequency of the color subcarrier, then in the first multiplier 9 the RF part of the PCVS is transferred such that the resting frequency of the color subcarrier is combined with zero frequency and as a result of multiplication, a complex envelope of the FM signal with reduced deviation due to negative frequency feedback is formed . In this case, the bandpass filter 10 is a low pass filter with a controlled passband, since its center frequency is aligned with zero.

 In the negative frequency feedback loop, frequency detection of the complex envelope in the complex signal frequency detector 15 and frequency modulation of the generator of the complex FM signal 12 with deviation opposite in sign of the deviation of the color signal contained in the PCVS are performed sequentially.

 The frequency band of the bandpass filter 10 depends on the magnitude of the jumps in the frequency of the color subcarrier. This dependence is provided by a chain of series-connected frequency detector 15 of the complex signal, differentiation unit 13 and driver 14. The parameters of these devices and filter 10 are selected so that the filter bandwidth at small differences, for example, less than 0.25 of the luminance signal span, 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 shaper 14 of the controlled signal.

 BZ 3, 6 serve to coordinate the delays of signals in parallel branches. In the multiplier 11, 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. 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 first 5 and second 8 DACs, the luminance and color signals are converted into 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 following notch of the spectrum of the brightness 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, to make separation more efficient than in known devices, since the same degree of mutual interference suppression is achieved at the cost of less distortion of the shared signals . Thus, the object of the invention is achieved.

Claims (1)

 A DIGITAL BRIGHTNESS AND COLOR SIGNALING DEVICE DEVICE IN THE SECAM SYSTEM DECODER, which contains the first delay block and subtractor in series, a tunable band-pass filter and a complex frequency-modulated (FM) signal generator, characterized in that, in order to reduce distortion of the luminance and color signals, a series-connected analog-to-digital converter, the input of which is an input of a full color video signal, a block for dividing a full color video signal (PCVS) into a low-hour total (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 a digital-to-analog converter (DAC), the output of which is the output of the brightness signal, the first multiplier, the first input of which is connected to the input of the first block delays and the second output of the separation unit (PCVS) into (LF) and (HF) components, the second DAC, the output of which is the output of the color signal, the second multiplier, the first input of which is connected to the first output of the complex FM signal generator, W The second input is connected via a tunable bandpass filter to the output of the first multiplier, and the output is from the second input of the subtractor and the input of the second DAC, and the frequency detector is connected in series, the input of which is connected to the second input of the second multiplier, the differentiation unit and the driver of the control signal, the output of which is connected to the second the input of a tunable band-pass filter, the input of the complex FM signal generator is connected to the output of the frequency detector, and the second output is connected to the second input of the first multiplier.