SU1713120A1 - Corrector of cross-color distortions - Google Patents

Abstract

The invention relates to television, concerns the formation of a signal in the encoder SECAM I and can be used in the equipment of analog-digital studio television sets of television broadcasting. The device is intended for correcting the chroma-chroma interference in the channel of a bright signal of the digital encoder of the SECAM system. The aim of the invention is to reduce distortion of the luminous signal. Corrector of cross-distortions in the encoder of the SECAM system contains two filters 1 and 12 low frequencies, two blocks 2 and 3 delays, subtractor 4, two multipliers 5 and 8, filter 6 with amplitude-frequency characteristic (AFC) of low-frequency (LF) equivalent of the correction circuit high-frequency (HF) predistortion, 0 | 'limiter 7, adder 8, generator 10 of the complex signal of the frequency 4.286 MHz, filter 11 with the frequency response of the LF equivalent of the chain of the high-distortion. 1 il.COC

Description

It

m so

hO o

 g

Yu

The invention relates to television, in particular to the formation of a signal in a CECAM encoder. and can be used in the equipment of analogue-digital studio-based television broadcasting complexes for correcting the brightness-chroma interference in the channel of the signal strength of the digital encoder of the SECAM system.

The purpose of the invention is to reduce the distortion of the luminous signal.

The drawing shows a structural electrical circuit of the proposed cross-distortion corrector.

Corrector of cross-distortion in the encoder of the SECAM system contains the first low-pass filter 1 (LPF), the first and second blocks 2 and 3 delays, the subtractor 4, the first multiplier 5, the filter 6 with the amplitude-frequency characteristic (AFC) of the low-frequency (LF) circuit equivalent correction of high frequency (HF) signals, limiter 7. second multiplier 8, adder 9. generator 10 of the complex signal at 4.286 MHz, filter 11 with amplitude-frequency characteristic (AFC). equivalent circuit of high frequency (HF) predistortion and the second low pass filter 12.

Corrector works as follows.

The luminance signal is fed to the input of the device and is divided into two channels.

The first low-pass filter 1. which enters the first channel, extracts its low-frequency component from the signal spectrum, the spectrum of which is concentrated in the 0-3 MHz frequency band.

In the second channel, the input signal is delayed by the 1st block 2 delays by a time equal to the delay time of the first low-pass filter 1. In the subtractor 4, its low-frequency part is subtracted from the delayed input signal and a high-frequency signal is formed, whose spectrum is concentrated in the 3-6 MHz band.

In the high-frequency signal, nonlinear spectral rejection is performed in the region of the deviation of the color subcarrier using the first multiplier, filter 6. limiter 7, filter AND, the second low pass filter 12, and the second multiplier 8.

The low frequency signal is delayed by the BTdporo delay element 3 for a time equal to the high frequency signal delay. In the adder 5, the low-frequency and high-frequency parts of the signal are added, and the signal received at the output of the device represents the luminous signal conforming to the SECAM standard.

Spectrum rejection in the color subcarrier deviation region is carried out as follows.

In the first multiplier 5 HF part

The signal is multiplied by the complex exponential signal W | (t) exp (I2jrfot) generated by the composite signal exponent generator 10 of the 4.286 MHz frequency, resulting in its spectrum being transferred in such a way that the frequency of 4, 286 MHz moves to the zero frequency point. As a result, in the spectrum of the high-frequency part of the signal, it becomes possible to isolate part of the spectrum in the region of the color deviation

subcarrier with. low-frequency equivalent bandpass filter. As such a filter, a complex signal filter 6 is used, which is the low-frequency equivalent of a correction circuit.

high frequency predistortion (LFE ESP).

After limiting the signal 7 from the output of the low-frequency equivalent circuit (LFE), this signal undergoes an inverse frequency conversion in filter 11, which is the low-frequency equivalent of the high-frequency predistortion circuit (LFEL). The spectrum of the received signal is limited by the second low-pass filter 12, after which the spectrum is reversed in the second multiplier 8 by multiplying by the signal the exponent W complexly conjugated with respect to the signal Wl

Claims (1)

Invention Formula Corrector of cross-distortion in the encoder of the SECAM system, which contains the sequentially connected first delay unit, whose input is the input of the corrector of cross-distortions in the encoder of the SECAM system, subtractor, first multiplier and filter with amplitude-frequency the characteristic of the low-frequency equivalent of the high-frequency predistortion correction circuit and the limiter connected in series the first low-pass filter whose input is connected to the input the second delay unit and the output connected to the second input of the subtractor, the second delay unit and the adder, the output of which is the output of the crosstalk corrector to the encoder of the SECAM system, and the second input connected to the output of the second multiplier, whose first input is connected to the first output of the integrated generator the signal frequency of 4.286 MHz, the second output of which is connected to the second input of the first multiplier517131206 Bodies, characterized in that, with a view to the equivalent of the B-circuit: high-frequency distortion of the signal-predistortion and the second low-pass filter, are connected in series connected between the output of a filter with an amplitude-frequency characteristic of the body and the second input of the adder.