SU879762A1 - Device for discriminating square-wave pulse signals - Google Patents

Description

The invention relates to a pulse technique, in particular, to devices for isolating symmetric pulse signals against interference. A device used to isolate pulsed signals, selectors in amplitude and duration IJ, are known. The selection of useful signals from interference in the device is achieved by simultaneously processing the original signal in the amplitude selector and selector in duration. The output signals of the selectors are fed to the corresponding inputs of the coincidence circuit. The response at the output of the coincidence circuit appears only for those signals that have been sampled in both amplitude and duration. This device suppresses interfering pulses with a NEXT amplitude and a short duration, or pulses that have a longer duration but a small amplitude. The known device does not provide suppression of noise and pulsed interference of high intensity, large in amplitude and duration, characteristic, for example, of a radio channel. The closest to the claimed technical essence is a device for selecting rectangular pulse signals containing two amplitude comparison units, the first inputs of which are connected to the signal input of the device, and the second with the corresponding sources of reference voltages, two triggers, two selectors in duration , time delay circuit, prohibition scheme and pulse generator 2. In this device, the source signal is sequentially processed by an amplitude selector (rejection of low amplitude emissions) and selectors the duration (short pulse rejection). At the same time, the input signal is fed to a second amplitude selector, consisting of an amplitude comparison unit, a source of reference voltages and a trigger. The reference voltage of the second selector exceeds the maximum voltage of the useful signal. Therefore, the signal at the output of the second amplitude selector appears only when exposed to emissions of large amplitude, i.e. under the action of intense pulsed

interference. This signal blocks the output of the device with the help of the prohibition circuit, thereby excluding from the output sequence impulse noise of any duration but large amplitude

Thus, blocking the output device causes indiscriminate suppression of impulse noise, resulting in the loss of the useful signal and low selection accuracy.

The aim of the invention is to improve the accuracy of the selection of symmetric pulsed signals when exposed to interference.

The goal is achieved by the fact that in the known device, which contains two amplitude comparison blocks, the first inputs of which are connected to the signal input of the device, and the second - with the corresponding sources of reference voltages, a trigger and a selector in duration, the element OR, two elements AND, an inverter and three shapers, with the output of the first amplitude comparison unit being connected through the first driver to the first input of the OR element and the first input of the first element AND, the output of the second amplitude comparison unit connecting through the second pho worldizer with the second input of the OR element and through the third driver - with the second input of the second element I, the first input of which is connected via an inverter to the output of the duration selector and the output bus of the device, and the output is connected to the second input of the trigger, the first input of which is connected to the output of the OR element, and the trigger output is connected to the second input of the first element I, the output connected to the input of the duration selector.

FIG. 1 shows a functional diagram of a device for selecting rectangular pulse signals; in fig. 2 - timing diagrams for the operation of the device.

The device contains two blocks 1 and 2 of amplitude comparison, the outputs of which are connected through two shaper 3 and 4 to the element OR 5 and, accordingly, to the first element AND 6 and to the third driver 7, trigger 8, the first input of which is connected to the output of the element OR 5, the second input is to the output of element 9. The trigger output is connected to the second input of element 6, the output of which is connected to the input of the selector in duration 10. The output of the selector is connected to the output bus of the device and through an inverter 11 to the input of the element 9. Sources of reference voltages 12 , 13 connect enes according to blocks 1,2 comparison.

The device works as follows. .

The input signal (Fig. 2a), which is a combination of a rectangular pulse signal and interference, is fed to the inputs of two comparison units, where it is compared with the reference voltages U and Ug.

The first block 1 of the comparison is the selection of the useful signal and its normalization by amplitude. At its output, working pulses and spurious pulses are formed, corresponding to emissions of interference, exceeding the reference voltage U. (Fig. 2b).

The second comparison unit works like the first, but it has a higher reference voltage, 0 ,. It provides the release of intense interference and generates pulses corresponding to emissions of a concentrated pulse interference and intense emissions of noise interference.

The pulse sequence from the output of the comparison unit 2 (Fig. 2b) is fed to the imaging unit 7, and from the output of the unit 1 (Fig.26) - through the AND 6 element to the input of the selector 10 in duration. The selector 10 suppresses both negative and positive pulses, the duration of which is less than the specified one and shifts the signal by a time longer than the delay of the interference pulses at the output of the comparator unit 2 relative to this. the same pulse from comparison unit 1 (Fig. 2d).

The pulses from the output of the selector 10 are inverted by an inverter 11 (Fig. 2e and are fed to the first input of the element AND 9, the second input of which receives a signal from the driver 7. The last generates pulses corresponding to the leading edge of the emission of interference (Fig. 2e). Element 9 It skips the indicated pulses only under the condition that at the moment at its first input there is an allowable potential.

Claims (1)

This corresponds to the lower level of the useful signal (Fig. 2k). The output pulses of the element And 9 set the trigger 8 to state 1. The signal from the trigger 8 (Fig. 2l) blocks the cell of the AND 6, excluding the interfering pulses from the output sequence useful sign level. However, the blocking will not be complete (Fig. 2m), since the interference pulses at the output of the comparison block 2 are the same as those at the output of the comparison block 1, as a result of the blocking, interference pulses will remain, the duration of which is determined by the distance between the reference levels 1) and Uij and the duration of the emission spikes. The remaining short pulses are suppressed by the selector 10 (FIG. 2d). The output of the selector 10 is the output of the device. The flip-flop 8 is reset by pulses from the 4 T generator (Fig. 2g), corresponding to the rear of the ejection front of interference, and pulses, corresponding to the trailing edge of the working pulse, from the Former 3 (Fig. 2h). In this case, the signal from the driver 3 sets the trigger 8 to the state O in the absence of interference. The device provides high-quality selection of rectangular pulsed signals by selectively suppressing intense pulsed noise. The invention The device of selection of rectangular pulse signals containing two amplitude comparison units, the first inputs of which are connected to the signal input of the device, and the second - with the corresponding sources of reference voltages, trigger selector, characterized by the fact that the selection of rectangular symmetric pulsed signals under the influence of interference, an OR element, two AND elements, an inverter and three shapers are introduced into it, and the output of the first amplitude comparison unit is connected via The first driver with the first input of the OR element and the first input of the first element AND, the output of the second amplitude comparison unit is connected through the second driver to the second input of the OR element and through the third driver to the second input of the second element AND, the first input of which is connected to the output of the duration selector and the output bus of the device, and the output is connected to the second input of the trigger, the first input of which is connected to the output of the OR element, and the output of the trigger is connected to the second input of the first element And, the output connected with entrance on the duration of the selector. Sources of information taken into account in the examination 1. Patent IT 3437833, cl. 307-231, publ. 19692. Patent IT 3961271, cl. 328-111, publ. 1976 (prototype). fff // L7 Fg / g f Or fft S 6 P