RU2012162C1 - 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 video signal into high-frequency and low- frequency constituents, two delay units 3, 6, adder 4, two digital-to analog converters 5, 18, subtraction unit 7, seven multipliers 8, 10, 15, 17, two tracing band-pass filters 9, 16, two frequency-modulated signal generators 11, 19, two signal differentiating circuits 12, 20, two control signal generators 13, 21, two frequency detectors of complex signals 14, 22. Frequency shift of high-frequency constituent of integral video signal as well as use of different methods for control of passing bands in tracing band-pass filters and introduced frequency feedback provide possibility to set optimal methods for change passing bands in color and brightness channels. These methods depend on size of frequency jumps in feedback circuits. This results in more effective separation of color and brightness signals. EFFECT: decreased distortion in brightness and color signals. 1 dwg

Description

 The invention relates to the field of 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.

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

 A device for separating luminance and chrominance signals in decoding devices of the SECAM system (ed. St. USSR N 1172082, class H 04 N 11/18, published. 1985), which contains the first servo bandpass filter and serially connected subtractor and adder.

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

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

 This is achieved by the fact that the device is additionally connected with 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, and the first delay unit, the output of which is connected to the input of the adder, the output of which is connected to input 1 -th DAC, the output of which is the output of the luminance signal, the 2nd delay unit, the input of which is connected to the 2nd output of the PCVS separation unit for low and high frequency components, and the output - with the 1st input of the subtractor, 4th multiplier, output which is connected to si the main input of the tracking band-pass filter (SPF), the 2nd multiplier, the first input of which is connected to the output of the 1st SPF, and the output is connected to the 2nd input of the subtractor, the 1st generator of the complex FM signal, the 1st and 2nd the outputs of which are connected respectively with the 1st input of the 1st multiplier and the 2nd input of the 2nd multiplier, connected in series with the 1st frequency detector (BH) of the complex signal, the input of which is connected with the output of the 1st SPF, 1st block signal differentiation (BDS) and the 1st non-linear converter (NLP), the output of which is connected to the control input the 1st SPF, in series with the 3rd multiplier, the input of which is connected to the inputs of the 1st multiplier and the 2nd delay block, the 2nd SPF, the 4th multiplier and the 2nd DAC, the output of which is the output of the color signal , The 2nd generator of a complex FM signal, the 1st and 2nd outputs of which are connected respectively with the 2 inputs of the 3rd and 4th multipliers, and the 2nd BH of the complex signal, the input of which is connected to the output 2, are connected in series 2nd SPF, 2nd BDS and 2nd NLP whose output is connected to the control input of the 2nd SPF, and the inputs of the 1st and 2nd generators to The complex FM signal is connected to the outputs of the 1st and 2nd BH complex signals, respectively.

 The drawing shows a structural diagram of the proposed device.

 The proposed device for separating luminance and color signals in the decoder of the SECAM system contains ADC 1, block 2 for separation of PCVS into low and high frequency components, 1st 3rd and 2nd 6th delay units (BS), adder 4, subtractor 7, 1st 5 and 2nd 18 DACs, 1st 8th, 2nd 10th, 3rd 15th and 4th 17th multipliers, 1st 9th and 2nd 16th SPF, 1st 11th and 2nd 19th complex generators FM signal, 1st 14th and 2nd 22nd BH complex signal, 1st 12th and 2nd 20th BDS and 1st 13th and 2nd 21th control signal conditioners (FSF).

 ADC 1 is connected between the input of the device and the input of block 2 for dividing the PCVS into LF and HF components, the 1st output (LF) of which is connected through the 1st БЗ 3, the adder 4 and the 1st DAC 5 with the output of the device brightness signal.

 The 2nd output of the RF block 2 of the separation of the PCVS into the LF and RF components is connected through the 2nd БЗ 6 with the 1st input of the subtractor and with the 2nd input of the 1st 8 and 1st input of the 3rd 15 multipliers. The output of the subtractor 7 is connected to the 1st input of the adder 4.

 The output of the 1st multiplier 8 through the 1st SPF 9 and the 2nd multiplier 10 is connected to the 2nd input of the subtractor. The output of the 3rd multiplier 15 through the 2nd SPF 16, the 4th multiplier 17 and the 2nd DAC 18 is connected to the output of the color signal of the device.

 The inputs of the 1st and 2nd BH KS 14, 22 are connected, respectively, with the outputs of the 1st and 2nd SPF 9, 16. The outputs of the 1st 14th and 2nd 22nd BSS through the 1st 12th and 2nd 20th BDS and the 1st 13th and 2nd FUS 21 are connected respectively to the control inputs of the 1st and 2nd SPF. Between the outputs of the 1st and 2nd BH CS and the 1st input of the 1st 8th and 2nd input of the 3rd 15th multipliers, respectively, the 1st 11th and 2nd 19th integrated FM signal generators, 2nd the outputs of the 1st and 2nd generators of the integrated FM signal are connected respectively to the 2 inputs of the 2nd and 4th multipliers.

 In the digital implementation of the device, signal processing in it is carried out, for example, in an 8-bit digital code.

 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 2, the LF part in band 0 is extracted from the spectrum of PCVS. . 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 rejected, and the resulting luminance signal is generated at the output of the adder 4, which is converted to analog form using the 1st DAC 5. The RF component of the PCVS arrives at the 1st inputs of the 1st 8th and 3rd 15th multipliers.

 Circuits from the 1st BH KS 14, the 1st generator of the integrated FM signal 11 and the 1st multiplier 8 in the channel of the formation of the BC component of the luminance signal and from the 2nd BH KS 22, the 2nd generator of the integrated FM signal 19 and 3- th multiplier 15 in the channel of the formation of the color signal are frequency feedback circuits; The 1st and 2nd generators of the integrated FM signal 11 and 19 have a frequency deviation opposite in sign of the frequency deviation of the color subcarrier signal in the PCVS. The outputs of the 1st and 2nd generators of the integrated FM signal 11 and 19 generate the corresponding complex FM signals, multiplying them by the RF component of the PCVS reduces the frequency deviation in this signal, and this allows the use of narrower 1st and 2nd SPF than in the prototype, and thereby improve the quality of separation of luminance and color signals.

 In the 1st SPF 9, the rather narrowband part of the spectrum, concentrated in the region of the instantaneous frequency of the color subcarrier, is allocated from the RF component of the PCVS. This contributes to its noise-tolerant isolation. The frequency band of the 1st SPF depends on the magnitude of the jumps in the frequency of the color subcarrier. This dependence is provided by a chain of sequentially connected 1st BH KS 14, 1st BDS 12 and 1st FUS 13 in the frequency feedback loop. The parameters of these devices and the 1st SPF 9 are selected so that the frequency band of the 1st SPF 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 1st FUS 13.

 The signal from the output of the 1st SPF 9 after the frequency reverse transfer in the 2nd multiplier 10 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 is dynamically rejected from color subcarrier.

 In the 2nd SPF 16, the narrow-band part of the spectrum, concentrated in the region of the instantaneous frequency of the color subcarrier, is also allocated from the RF component of the PCVS, which contributes to its noise-tolerant selection. The frequency band of the 2nd SPF can depend on the size of the frequency jumps of the color subcarrier, for example, according to the law, when the bandwidth is very small, for example, 100 kHz, below the threshold level of the differentiated signal of frequency jumps (at which mostly noise goes into the color channel) and when the frequency jumps exceed the threshold level, the band is selected as maximum and decreases as one strives for the maximum attainable level of jumps. This dependence is provided by a chain of series-connected 2nd BH KS 22, 2nd BDS 20 and 2nd FUS 21 in the frequency feedback loop. In the 4th multiplier 17, the spectrum of the chroma signal is reversed.

 Delay blocks 3 and 6 are used to coordinate the delays of the signals in parallel branches.

 Frequency transfer of the RF component of the PCVS in combination with the use of different laws for controlling the passband of the servo filters in the luminance and color channels, as well as the use of frequency feedback, which makes it possible to establish optimal laws for changing the passband in these channels, depending on the amplitude of the frequency jumps in the feedback loops communication, makes 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 sharing persecuted.

Claims (1)

 DIGITAL BRIGHTNESS AND COLOR SIGNAL SEPARATION DEVICE IN THE SECAM SYSTEM DECODER, containing the first servo-bandpass filter and series-connected subtractor and adder, characterized in that, in order to reduce brightness and color distortions, a series-connected analog-digital converter, the input of which is the input of the full color video signal (PCVS), the block separation PCVS into low-frequency (LF) and high-frequency (HF) components and the first delay unit, the output of which is connected to the second input the adder, the output of which is connected to the input of the first digital-to-analog converter (DAC), the output of which is the output of the luminance signal, the second delay unit, the input of which is connected to the second output of the block for the separation of the PCVS into the LF and HF components, and the output to the first input of the subtractor, the first multiplier, the output of which is connected to the signal input of the first servo-bandpass filter, the second multiplier, the first input of which is connected to the output of the first servo-bandpass filter, and the output - with the second input of the subtractor, the first generator a torus of a complex frequency-modulated (FM) signal, the first and second outputs of which are connected respectively to the first input of the first and second inputs of the second multipliers, the first frequency detector of the complex signal, the input of which is connected to the output of the first servo bandpass filter, the first signal differentiation unit, and the first driver of the control signal, the output of which is connected to the control input of the first servo bandpass filter, the third multiply connected in series a device whose input is connected to the inputs of the first multiplier and the second delay unit, a second servo bandpass filter, a fourth multiplier and a second digital-to-analog converter, the output of which is an output of a color signal, a second generator of a complex FM signal, the first and second outputs of which are connected respectively to the second inputs the third and fourth multipliers, and sequentially connected to the second frequency detector of the complex signal, the input of which is connected to the output of the second tracking band phi tra second differentiating unit and a second signal generator of the control signal, the output of which is connected to the control input of the second tracking bandpass filter and inputs of the first and second generators integrated FM signal connected to the outputs of the first and second frequency detector complex signal.