SU362510A1 - • UNITED SHENTKY-TECHINNESS - Google Patents

Description

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The invention relates to the field of color television, in particular, to decoding devices of color television receivers and color video monitoring devices according to the SECAM system.

A decoder of a color television receiver is known, which contains channels of direct and delayed signals, the outputs connected to the signal inputs of an electronic switch controlled by a relaxation generator, connected to the differential channels.

The purpose of the invention is to increase the reliability of color recognition by the decoder. This is achieved by connecting the inputs of the direct and delayed channels through identical resonant circuits to the inputs of the mixer, the output of which is connected to the input of the relaxation generator through a detector and a correction circuit.

FIG. 1 nr. The block diagram of the proposed device; on fng. 2 - time diagrams, according to his work.

The device works as follows.

The inputs of the electronic switch /, directly and through channel 2 of the delayed signal, are provided with a color signal from the input 3 of the device. Direct communication can be made by channel 4 of the visible signal, amplifying without delay the chroma signal. The electronic switchboard / is controlled by a relaxation generator 5, to the input 6 of which the horizontal frequency signals are supplied, and to the input 7 - correction (identification) signals. The outputs of the electronic switch 1 are connected to the inputs 8 to 9 of the color difference channels, in which the limitation, amplification and demodulation of the chrominance signals are implemented. The ER and Y color difference signals are output at the W and // outputs of these channels. Two identical resonant circuits / 2 and 13 are tuned to the frequencies corresponding to the flat parts of the recognition signals ds and dn. The output of the mixer 14 through the detector 15

and the correction circuit 16 is connected to the input 7 of the correction of the relaxation generator 5.

Correction circuit 16 can be made in the form of a limiter or a resonant cascade tuned to half of the line part; .

At the inputs of the electronic switch /, two sequences of signals shifted in time by one line in which the subcarrier packets corresponding to the rows and dn alternate, the direct signal is fng. 2.0, delayed - FIG. 2.6. These signals arrive at the inputs of the selective circuits 12 and 13. Let the circuit 12 be tuned to the frequency of the signal ID, and the circuit 13 to the frequency of the signal da. Then, at the inputs of the mixer 14, the signals shown in FIG. 2, c, d. In these signals, the components d and d-c are separated and present through the line. At the output of the mixer 14, oscillation packets are separated at a frequency equal to the frequency difference of the subcarrier during the transmission of signals d and ds. These packets, after being detected by detector 15, are converted into square pulses shown in FIG. 2.5 The phase of the pulses depends only on the determining phase of the switch on the transmission side. If the phase of the relaxation generator 5 is correct, then the identification pulses (FIG. 2,) confirm its state, and the operation of the generator does not change. In the case of an incorrect phase, the identification pulses cause a generator correction, after which they again re-byte a lead on its T1-C1.

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If the corrective circuit b contains a resonant cascade, tuned to the first harmonic of the pulses, then due to its filtering action, the noise immunity of the system is further increased, and a sinusoidal signal is received on input 7 (Fig. 2, e).

Since the recognition signal appears only when a color program is received, it can also be used to automatically turn on a decoding device, for example, using a known asymmetric trigger scheme.

The considered scheme corresponds to one of the possible variants of the proposed decoding device, which can be made by combining the mentioned resonant circuits and the mixer with the outputs of the electronic switch /, to the auxiliary control input of which the frame frequency signals are received, thus achieving alternating components dji and the selection at the output of the detector / 5 repeats each row of pulse identification (Fig. 2, g), which, after integration, provides It treats the noise protection of the decoding device, using a wide pulse (Fig. 2, h).

Subject invention

A SECAM receiver decoder containing the direct and delayed channels, outputs connected to the signal inputs of an electronic switch controlled by a relaxation generator connected to color difference channels, characterized in that, in order to improve color recognition reliability, the channels of the direct switch Through the identical resonant circuits, the inputs of the mixer are connected, the output of which is connected to the input of the relaxation generator through a detector and a correction circuit.

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