SU1172081A1 - Colour difference pal signal channel of pal-secam decoding device - Google Patents

Abstract

A PEA-SECAM PAL SIGNAL CHANNEL of a PAL-SECAM decoder device containing an adder and a subtractor, the first combined inputs of which are the first input, the second combined inputs by the second input, and the third combined inputs by the third input of the color difference signal channel of the PAL-LED decoder. the adder and subtractor are connected respectively to the first inputs of the demodulator of the signal B-Y and the demodulator of the signal RY, whose outputs are outputs of the color difference signals, the second output of the sums torus is connected to the first input of the first phase detector, the second input of which is connected to the first output of the PAL reference subcarrier generator, the first input of which is connected to the output of the first phase detector, and the second output to the second input of the demodulator of the B-Y signal, characterized in that in order to increase noise immunity by eliminating sinusoidal interference from the PAL subcarrier generator when receiving a black-white television signal and the SECAM signal, the first phase-shifting unit is inserted into it, the second phase-shifting unit k, the phase shifter, the second phase detector, the first low-pass filter (LPF), the second low-pass filter, the switch and the OR element, the input of the first phase-shifting unit connected to the second output of the adder, and the output to the first input of the second phase detector, the second input of which is connected to the second output of the subtractor, and the first and second outputs are connected respectively via the first and i second LPF to the first and second inputs (L of the OR element, the output of which is connected to the second input of the generator PAL subcarrier and is the output of the enable signal chrominance, the input of the second phase-shifting unit is connected to the second generator output of the PAL supporting sub-carrier, and the output is connected to the first input of the switch and to the input of the phase shifter, the output of which is connected to the second input of the switch, the third and fourth inputs of tc are connected to the outputs of the first and second low-pass filters, and the output is with the second (about 00) input of the demodulator of the R-Y signal.

Description

The invention relates to television technology and can be used in color video monitoring devices and television receivers.

The purpose of the invention is to improve noise immunity by eliminating sinusoidal interference from a PAL subcarrier generator when receiving a black and white television signal and a SECAM signal.

FIG. 1 is a structural electrical circuit diagram of a PAL-SECAM color-difference signal channel of a PAL decoding device; FIG. 2 and 3 are vector diagrams that explain its operation at two possible phases of operation of a decoder switch.

The channel of the PAL color difference signal of the PAL-SECAM decoder (Fig. 1) contains adder 1, subtracter 2; demodulator 3 of the B-Y signal, demodulator 4 of the RY signal, first phase detector 5, first phase-shifting unit 6, second phase detector 7, first low-pass filter 8 (low-pass filter), second low-pass filter 9, generator 10 of the reference PAL carrier, second phase shifter AND, switch 12, phase shifter 13 and element OR 14.

Channel color difference signal PAL decoding device PAL-SECAM works as follows.

From the outputs of the electronic switchboard, which is a common element of the decoder for both the PAL channel and the SECAM channel, the first and second inputs of the adder 1 and subtractor 2 receive the PAL chromaticity signals delayed by one line, respectively, for Both possible switch phases are shown in FIG. 2a, b and za, b respectively.

From the first outputs of adder 1 and subtractor 2, the chrominance signals (Fig. 2c, g and Sv, g) are sent to the first inputs of demodulator 3 of signal B – Y and demodulator 4 of signal RY, and on the second outputs of adder 1 of subtractor 2 there are signals “ flashes gated in adder 1 and subtractor 2 by a signal arriving at their third inputs. Vector diagrams of the “flashes” on the second output of the adder are shown in FIG. 2d and Zd, and at the second output of the subtractor - in FIG. 2nd and Ze.

In addition, the signal "flashes from the second output of the adder 1 is fed to the first input of the first phase detector 5 and through the first phase-shifting unit 6 to the first input of the second phase detector 7 (Fig. 2g and Зж), to the second input of which comes the signal" flash with of the second output of Bichitel 2. The flashes on the first and second

(direct and inverse) outputs of the second phase detector signals are averaged by the first low pass filter 8 and the second low pass filter 9 (the waveform at the output of the first low pass filter 8 is shown in Figs. 2h and 3h).

The first phase detector 5 operates in the phase-locked loop of the generator 10, the reference subcarrier PAL, the first input connected to the output of the first

phase detector 5, the second input of which is connected to the first output of the generator 10 of the PAL reference subcarrier, the signal from the second output of which (Fig. 2 and Zi) is fed to the second input of the demodulator signal B-Y3 and to the input of the second phase-shifting unit 11, the output of which the signal of the reference subcarrier arrives at the first input of the switch 12 directly, and at the second input through the phase shifter 13.

When the input signals of the second phase detector 7 are in phase, the positive voltage from the output of the first low-pass filter 8 arrives at the third input of the switch 12, ensuring that the signal from the second input passes to its output, and otherwise the positive voltage from the output

5 of the second low-pass filter 9 is fed to the fourth input of the switch 12, ensuring the passage at its output signal from the first input. The vector diagram of the signal at the output of the switch 12 is shown in FIG. 2k and 3k, demodulators 3 and 4 of signals B – Y and R – Y are synchronous detectors, for operation of which the signal of the PAL reference subcarrier in the corresponding phase with the generator 10 output arrives at their second inputs.

5. Support subcarrier PAL and switch 12.

The positive voltage from the outputs of the first low-pass filter 8, or the second low-pass filter 9 is fed through the OR 14 element to the second input of the generator 10, the reference PAL subcarrier, allowing its operation. In the case of receiving a SECAM signal or a black-and-white television signal, positive voltages do not occur at the outputs of the first low-pass filter 8 and the second low-pass filter 9, as a result

5, the generator 10 of the reference subcarrier is blocked, thereby preventing interference occurring during its operation.

Thus, the application of the proposed channel color difference signal surfactant

0 in the PAL-SECAM decoder eliminates sinusoidal interference from the PAL subcarrier generator in cases where the PAL signal is not received, and thereby ultimately improves the image quality on the screen of the television receiver or video monitor.

e

Claims (1)

PAL-SECAM DECODING CALCULATOR CHANNEL CHANNEL containing an adder and subtracter, the first combined inputs of which are the first input, the second combined inputs are the second input, and the third combined inputs are the third channel input of the color difference signal PAL decoding device PAL-SECAM and a subtractor are connected respectively to the first inputs of the demodulator of the signal B — Y and the demodulator of the signal R — Y, the outputs of which are outputs of color-difference signals, the second output is summed and connected to the first input of the first phase detector, the second input of which is connected to the first output of the PAL reference subcarrier generator, the first input of which is connected to the output of the first phase detector, and the second output - to the second input of the signal demodulator B — Y, characterized in that, with In order to increase noise immunity by eliminating sinusoidal interference from the PAL reference subcarrier generator when receiving a black-and-white television signal and SECAM signal, the first phase-shifting unit, the second phase-shifting unit, phases are introduced into it a splitter, a second phase detector, a first low-pass filter (LPF), a second low-pass filter, a switch and an OR element, the input of the first phase-shifting unit being connected to the second output of the adder, and the output to the first input of the second phase detector, the second input of which is connected to the second output a subtractor, and the first and second outputs are connected respectively through the first and second low-pass filters with the first and second inputs of the OR element, the output of which is connected to the second input of the PAL reference subcarrier generator and is the output of the color enable signal, the input to The second phase-shifting unit is connected to the second output of the PAL reference subcarrier generator, and the output is connected to the first input of the switch and to the input of the phase shifter, the output of which is connected to the second input of the switch, the third and fourth inputs of which are connected to the outputs of the first and second low-pass filters, and the output to the second input of the demodulator signal R — Y.