SU1552405A1 - Correction of cross-colour distortions in secam system - Google Patents

Abstract

The invention relates to television. The purpose of the invention is to improve the accuracy of the correction of cross-distortion. The corrector contains filters 1 and 5, limiter 2, subtractors 3 and 7, delay blocks 4, 6 and 11, multipliers 8 and 9, adder 10 and generator 12 of the complex subcarrier signal. In this corrector, splitting the spectrum of the input signal into two components eliminates the effect of notching on the low-frequency part of the spectrum of the input signal, and using the transfer of the spectrum of the signal to be rejected to zero frequencies reduces the overlap of the primary and secondary spectra of the filtered signal. This provides improved accuracy of correction of cross-distortion. 2 Il.

Description

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The invention relates to television technology and can be used in the composition of the studio analog-digital equipment television centers

The purpose of the invention is to improve the accuracy of the correction of cross-distortion.

FIG. Figure 1 shows the structural (electrical diagram of the cross-distortion corrector of the encoder of the SECAM system; Fig. 2 shows spectral diagrams explaining the operation of the corrector.

Corrector cross-distortion encoder system SECAM contains the first filter 1, limiter 2, the first subtractor 3, the first block 4 delay, the second filter 5, (the second block b delay, the second subtractor 7, the first multiplier 8, the second multiplier 9, the adder 10, ( the third block 11 of the delay and the generator of the integrated signal 12 subcarrier. The corrector works as follows,

1 A luminance signal input to the input, having a band in the order of 6 MHz (Fig. 2a), is limited in bandwidth in the second filter 5 to about -sample 3 MHz (Fig. 26). At the same time, the input signal passes through the second delay unit 6, which compensates for the delay in the second filter 5, and is fed to the first input of the second subtractor 7 to the second input of which the output signal of the second filter 5 arrives. As a result, at the output of the second subtractor 7 the spectrum of the input signal (Fig. 2c), which goes further to the first input of the first multiplier 8, in which it is multiplied by the signal of the complex exponent:

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As a result, the spectrum of the high-frequency part of the input signal is transferred in such a way that the frequency of 4.286 MHz is transferred to the point of zero frequency (Fig. 2d). Due to this, it becomes possible to cut the color subcarrier signal with a low-frequency equivalent of a bandpass filter.

The decal is carried out as follows: The first filter 1 selects

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from the output Fignal of the first multiplier 8, components located in the vicinity of the zero frequency, the characteristic of the first filter 1 being the low-frequency equivalent of the high-frequency predistortion correction circuit. After restriction in limiter 2, the output of the first filter 1 is fed to the first input of the first subtractor 3, to the second input of which, through the first delay unit 4, the output of the first multiplier 8 arrives. As a result, a signal with the spectrum shown in FIG. 2d

Next, in the second multiplier 9, by multiplying the complex exponent by the signal, the spectrum is transferred back from the zero frequency range to the frequency 4.286 MHz (Fig. 2e), after which the output signal of the second multiplier 9 is summed in the adder 10 with the low frequency portion of the input signal delayed by the third a delay unit 11 for processing time in blocks 7, 8, 1-4, and 9. As a result, a full-band signal with the spectrum 1 shown in FIG. 2g.

The generation of complex subcarrier signals required for operation of multipliers 8 and 9 is performed by generator 12.

Splitting the spectrum of the input signal into two components eliminates the influence of the direction on the low-frequency part of the spectrum of the input signal, and using (transferring the spectrum of the signal to be rejected to zero frequencies reduces the overlap of the primary and secondary spectra of the filtered signal, which, all other things being equal, provides an increase in accuracy of correction of cross distortions.

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Claims (1)

Invention Formula The CECAM system encoder's cross-distortion corrector, containing a first filter connected in series, a limiter and a subtractor, the second input of which is connected to the first filter's input through the first delay block, characterized in that, with a circuit to improve the accuracy of the correction of cross distortions, five filter, second and third delay blocks, second subtractor, first and second multipliers, and adder and complex carrier signal generator, the first filter made in the form of a low-pass filter, the combined inputs of the second delay block and the second filter, also in the form low pass filter, are the input of the luminance signal, the output of the second delay unit through a serially connected second subtractor and the first multiplier 1552i 056 pa, the output of the second filter connect to the second input of the second and subtract from the input of the third block g the output of the first subtractor through the second multiplier and the adder connected to the course of the corrector cross and live encoder C 10 we SECAM, the second input of the adder is dinene with the output of the third block the holders and the second inputs of the first multiplier ryh multipliers are connected to the corresponding outputs of the generator  - - f- - wii I-- .. -.-.- .. .g. Bb flrt | wrlGUCl I The tel is connected to the input of the first filter-15 complex subcarrier signal 01MHz PG1 0 MHz F - 1552i 056 pa, the output of the second filter is connected to the second input of the second subtractor and to the input of the third delay unit, g the output of the first subtractor is connected through the second multiplier and the adder are connected to the output of the cross-distortion corrector of the CECAM encoder, the second input of the adder is connected to the output of the third the delay unit, and the second inputs of the first and second multipliers "connected to the corresponding outputs of the generator I-- .. -.-.- .. .g. Bb flrt | wrlGUCl I - 15 complex subcarrier signal GUL 3 4,286 6 MHz P