SU815965A1 - Non-linear frequency video signal corrector - Google Patents

Description

(54) NONLINEAR-FREQUENCY VIDEO CORRECTOR

I

The invention relates to radio engineering and can be used to correct signals in television systems.

Known nonlinear frequency corrector video signal containing the first low-pass filter and band-pass filter, the inputs of which served the video signal, Ghri this output of the first low-pass filter connected to the first input of the first adder through the first delay line, the second input of which is connected to the output of a bandpass filter two way limiter at minimum 1.

However, the known corrector provides a relatively low signal-to-noise ratio of low contrast details of the image.

The purpose of the invention is to increase the signal-to-noise ratio of low-contrast image details.

The goal is achieved by introducing a serially connected double-sided limiter to the nonlinear video signal equalizer, a second low-pass filter, a second two-way minimum limiter, and a second adder, while the double-sided limiter is maximally connected to the output. the band-pass filter, and the output of the second two-way limiter is minimum connected to the first input of the entered second adder, to the second input of which the output of the first adder is connected via the entered second delay line.

The drawing shows the structural scheme of the proposed corrector.

Nonlinear frequency video signal corrector contains a bandpass filter 1, the first lowpass filter 2, the first delay line 3, the first adder 4, the first two-way limiter 5 at the minimum, the second delay line 6, the two-way limiter 7 at the maximum, the second filter 8 of the lower frequencies, the second two-way limiter 9 for the minimum and the second adder 10.

Nonlinear frequency video corrector works in the following way.

A video signal is input to the corrector, consisting of a sequence of video pulses of different duration and amplitude. Band-pass filter 1 and the first low-pass filter 2 pass separately high-frequency and low-frequency

video signal components. From the bandpass filter 1, the signal enters the two-way limiter 7 to the maximum and at the same time to the first two-way, limiter 5 to the minimum. At the output of the first bilateral limiter 5, the signal passes at those points in time when its span exceeds threshold levels. The signal from the output of the two-sided limiter 7 is fed to the maximum to the second low-pass filter 8, in which the relative attenuation of the high-frequency components of the spectrum of the incoming signal and noise is performed.

The signal obtained at the output of the second low-pass filter 8 goes to the second double-sided limiter 9 at a minimum and then to the first input of the second adder 10. The signal from the output of the first low-pass filter 2 through the first delay line 3 compensates the time shifts that occur when the signal passes through the band-pass filter 1 and the first two-way limiter 5 at the minimum, the output signals of the first two-way limiter 5 at the minimum arrive at the corresponding; and the inputs of the first adder 4. Next, the output signal of the first su mmatore 4, passed through the second delay line 6, compensating for the time shift that occurs when the signal passes through the double-ended organizer 7 to the maximum, the second low-pass filter 8 and the second two-sided stop 9 at the minimum, and the signal from the output of the second double-sided stop 9 at the minimum the corresponding inputs of the second adder 10, the output of which is allocated the corrected input video signal with a significantly increased signal-to-noise ratio compared to the signal-to-noise ratio at the input to Rector. The increase in the signal-to-noise ratio is determined by an appropriate choice of the low-pass filter band 8 and the thresholds of the two-way limiters 5, 7, 9.

The proposed non-linear frequency equalizer allows the dynamic range of the contrast of objects reproduced by the television system to be significantly expanded without increasing the dynamic range of the video link units in the system.

Claims (1)

1. Suslokov S. A., et al. Improving the noise immunity of the aperture correction circuit by the method of nonlinear processing of the image signal. -Cb. articles "Issues of noise immunity and resolution of radio systems (television and radio), Moscow, 1967, vol. 10, s. 21-25 (prototype).