SU1347193A1 - Device for separating maximum-level television signal - Google Patents

Abstract

The invention relates to television (TV) and improves accuracy by reducing the effect of impulse noise. The device contains a peak detector 1, a recursive filter 2, a strobe pulse shaper 3, comparators 4 and 5, an adder 6, a subtractor 7 and a logic unit 8. If there is a narrow peak-type noise in the signal, the level of which lies beyond the specified of the max range, signal levels, it is not recorded in the parallel register of detector 1 for further statistical processing in filter 2, which makes it possible to increase the reliability of signal processing and, therefore, noise immunity of the system, gr. about Uc Uon IHI L I DO CD 00

Description

The invention relates to television and can be used for preprocessing television (TV) signals in TV tracking systems.

The aim of the invention is to improve the accuracy of the discharge by reducing the effect of impulse noise.

Fig. 1 shows a structural electrical circuit of the device for extracting the maximum level of the TV signal; 2 is a structural electrical circuit of a digital version of the device.

A device for extracting the maximum level of a TV signal (FIG. 1) contains a peak detector 1, a recursive filter, 2, a gate pulse generator 3, a first 4 and a second 5 comparators, an adder 6, a subtractor 7, and a logic unit 8.

The digital version of the device for extracting the maximum level of the TV signal (FIG. 2) contains the first 9, the second 10 and the third P digital comparators, the digital input 12 of the threshold level, the first 13 and second 14 summators J parallel register 15, driver 6, two IGSH elements 7 and 18, elements AND 19 and 20 N elements NOT 21.1 element AND 22, the generator 23 clock pulses and the generator 2 sync pulses, the digital input 25 of the device and the input 26 of the operating mode of the device.

The device works as follows.

The device for extracting the maximum level of the video signal operates in two modes: in the peak detector mode, the maximum levels when the device's mode input is pa. bots have a logical O level, and in the analysis mode of maximum video signal levels, when logical level 1 is present at the input of the device operation mode and in which the TV tracking system is switched to the tracking mode,

In the peak detector mode, the device operates as follows. A TV signal is received at the input of the peak detector 1, which is converted into a constant voltage proportional to the maximum value. TV signal per half frame within a tracking strobe generated by shaper 3, Oscillator 23

five

0

five

 nofi. subtractor

0

five

0

45

50

55

clock pulses and a generator of 24 sync pulses, at the outputs of which frame and line damping pulses are formed, synchronize the operation of the device as a whole. According to the recording resolution signal from the second output of the imaging unit 3, the maximum for the current half-frame of the TV signal is recorded in the memory block of recursive filter 2, where the maximum values of the TV signal are accumulated and averaged, which is necessary for accurate and reliable operation of the tracking-system TV. Accumulation and averaging can be conducted according to the average or aperiodic laws,

The averaged value of the TV signal from the outputs of the recursive filter 2 enters the inputs of adder 6 and subtractor 7 (their digital analogs are adders 13 and 14 in FIG. 2), in which the algebraic addition of this value of TV signal occurs with a threshold level U At the outputs adder 6 and 7 are formed voltage levels, respectively equal to

UfHotKcx. - and ms1ks (-s - () + and not

U / iHHa - UMQ, P; ,,, J-.

which form the permissible range of variation of the maximum value of the TV signal for the subsequent half-frame, Voltage. and are fed to the second inputs of the comparators 4 and 5, where they compare the values of the TV signal with them on the subsequent half-frame.

Since when operating in the peak detector mode, the logic level O is present at the input of the device operation mode, the signals from the outputs of both comparators 4 and 5 are blocked in logic block 8, regardless of the presence of the logic level O or 1 at input 26 of the element AND 20 logical level 1.

When the device is operating in the level analysis mode, the level 26 of the operating mode of the device forms a logic level that allows control signals to pass from the comparators 4 and 5 outputs. When the current value of the TV signal does not go beyond the limits of the UMOKCX range, then the outputs of both comparators 4 and 5 appear

one

Logic 1 levels that pass in logic block 8 through elements 17-20 to store the current value of V in peak detector 1 (in parallel register 15) if the value of V exceeds the previously memorized value of the TV signal. When it is current. The value of V does not satisfy at least one of the inequalities, i.e. is outside the range of variation of the maximum value, then a logic level O appears at the output of the corresponding comparator, which, in passing in logic block 8 through elements 17-20, prohibits the recording of the current value of the TV signal V in peak detector 1.,. Thus, in the presence of TV. Signal.e pulse type of narrow-peak type, the level of which lies outside the specified range of variation of maximum levels of a TV signal, is not recorded in the parallel register 15 of the peak detector 1 for further statistical processing in the recursive filter 2, which allows increasing the accuracy of processing TB the signal at its subsequent stages, and hence, the interference immunity of the TV tracking system as a whole.

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Claims (1)

Invention Formula A device for extracting the maximum level of a television signal containing a peak detector, the input of which is the input of the device and connected to the first inputs of the first and second comparators, the second inputs of which are connected to the outputs of the adder and subtractor, the first inputs of which are the inputs of the threshold voltage the comparators are connected to the first and second inputs of the logic unit, and the first control input of the peak detector is connected to the first output of the strsb pulse shaper, characterized in that To improve the accuracy of the selection by reducing the effect of impulse noise, a recursive filter is introduced between the output of the peak detector and the second inputs of the adder and subtractor, the control input of which is connected to the second output of the strobe pulse former, the second input of the peak detector is connected to the output logic unit, the third input of which is the input of the device operation mode.