SU480198A1 - SECAM Chromaticity Television Unit - Google Patents

Description

one

This invention relates to color television.

A SECAM television receiver's chrominance block is known, which contains direct and delay channels, two frequency detectors, an electronic switch, a control input connected to a relaxation generator, and a matrix of a green color difference signal.

The purpose of the invention is to reduce cross-sectional distortions, as well as providing noise-proof color timing.

The proposed color block is characterized in that the direct and delay channels are connected to the signal source through the input stage, and the outputs through frequency detectors to the electronic switch inputs, one of which outputs is connected to the corresponding input of the green matrix of the color difference signal, and the other through phase inverter, with the output of one of the frequency detectors connected via a band-pass filter to the correction input of the relaxation generator.

The block diagram of the color block is shown in the drawing.

The unit consists of an input stage 1, a forward channel 2, a delayed drip 3, frequency detectors 4, 5, an electronic switch 6, a relaxation generator 7, a matrix of green color difference signal 8, a phase inverter 9.

The device works as follows. The color subcarrier signal enters through the input stage 1 into channels 2 and 3. At the outputs of these channels, direct and delayed signals that have passed the high-frequency predistortion correction circuits and are limited to the necessary degree are separated. These signals

arrive at the inputs of frequency detectors 4 and 5. The signals at the outputs of the detectors have the same polarity. On red lines, both signals are positive, on blue ones - negative. The signals on both outputs are distinguished only by the fact that one of them is backdated and compared to the other at the time of one line.

The demodulated signals from the detectors are sent to the electronic switch 6. How

and in a conventional decoder, the switch is controlled by a square-wave voltage with a half-line frequency. This direction is produced by a relaxation generator 7.

The electronic switch 6 must pass not the frequency band near the subcarrier, as in conventional decoders, but demodulated color difference signals. The upper bandwidth should be 1 -

1.5 MHz. Transfer constant component

optional, since it can be reconstructed in output amplifiers.

In order for both sninnas to have the same polarity, a phase inverter 9 is introduced into the circuit.

The reduction in cross-sectional distortions in the device is achieved due to the fact that it does not have the cost, linking their direct and delay channels. The parasitic links in switch 6 cause the demodulated color difference signals to be mixed not by the carrier, nx. At the same time, the image doesn’t appear interfering with the image, but the saturation and color tone of the colored areas of the image only slightly change.

Subject invention

Claims (2)

1. A SECAM television receiver's color receiver block, containing direct and delay channels, two frequency detectors, an electronic switch, a control input connected to a relaxation generator, and a matrix of a green color difference signal, characterized in that, in order to reduce cross distortion, the direct inputs and the delay channels through the input stage are connected to the signal source, and the outputs through the frequency detectors are connected to the inputs of the electronic switch, one of the outputs of which is connected to the corresponding input m matrix green color difference signal directly, and the other - through fazonnvertor. 2. The unit according to claim 1, characterized in that, in order to provide noise-proof color synchronization, the output of one of the frequency detectors is connected via a band-pass filter to the correction input of a relaxation generator.