SU972652A1 - Pulse duration discriminator - Google Patents

Description

(54) SELECTOR PULSE OF DURATION

The invention relates to a pulse technique and can be used in automatic control devices as a selector of maximum duration.

A pulse selector with a duration is known, comprising two inverters, two coincidence elements, a one-shot and a trigger. It is a pulse selector of both maximum and minimum duration, with the output of the maximum duration selector being the output of the coincidence element. The output pulse is the difference between the durations of the input pulse and the one-shot 1 pulse.

However, this device is not robust and allows false alarms if the interference pulse partially coincides with the one-shot pulse generated on the leading edge of the previous interference pulse.

The closest in technical essence and the achieved result is the pulse selector in duration, containing a trigger, a pulse counter, a delay element and the first element of the match, the first

the input of which is connected to the output of the delay element, and the second to the input of the delay element, the output of the delay element is connected via a serially connected trigger, the second and third match elements and a pulse counter to the third input of the first match element, and the second input of the second element coincides with the count input of the trigger is connected to the input of the delay element, and the second input of the third match element and the zero reset trigger are connected to the output of the delay element 2j.

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A disadvantage of the known device is the possibility of the appearance of spurious signals at the output, when the inhibit signal j blocking the first element of coincidence does not occur, then the coincidence of the input signal or interference pulse with the previous delayed pulse causes the appearance of spurious signals. This is possible in the case of

25 coincidence of the interference pulse with the previous delayed pulse (input signal or interference), when the falling edge of the interference pulse arrives earlier than the falling edge of the delayed pulse. The aim of the invention is to increase its noise immunity. The goal is achieved by the fact that, in a pulse selector, each containing a trigger, the direct and inverse outputs of which are connected to the first inputs of the first and second matches, the delay element whose input is connected to the selector input bus, and the output to the first the input of the third element of the match, entered the rectifier, pulse shaper, the first and second pulse expander element OR, the inverter and differentiated power supply chain, the input of which is connected to the input bus of the selector and the output through Consequently, the rectifier and pulse shaper are connected to the counting trigger input and the second inputs of the first and second match elements, the outputs of which are connected to the inputs of the OR element through the first and second pulse extenders, respectively, to the second input of the three matching elements. FIG. 1 shows a block diagram of the proposed device; in fig. 2 - timing diagrams for the operation of the device. Pulse selector by duration contains delay element 1, differentiating chain 2, rectifier 3, pulse shaper 4, trigger 5, first and second coincidence elements b and 7, first and second pulsers 8 and 9 pulses, OR 10, inverter 11 and the third element 12 is a match. The device also has an input 13 and output 14 tires. The delay time of the signal by the delay element 1 is chosen longer than the maximum total delay time of the accumulation of elements 3,4,5,6,8,10 and l or 3,4,5,7,9,10 and 11 and serves to ensure the delay of the arrival of the front The front of the input pulse to the first input of the element 12 coincides with the pulse at its second input. The constant time of the differentiating chain 2, as well as the trigger threshold of the driver 4, are selected in this way, the input interference pulses having an amplitude or duration less than a certain value at the output e ,, pulse shaper 4 does not occur. The duration of the pulses produced by the expanders 8 and 9 pulses determines the duration selection threshold. The pulses arriving at the counting input of trigger 5 switch it behind them with fronts, for example, odd pulses are set at its forward output 1, and even ones are set at O (or vice versa. The device works as follows. The first impulse received at the input bus 13 of the device as well as subsequent odd pulses (Fig. 2a) cause the appearance at the output of the imaging unit 4 pulses of duration V (Fig. 26), which are fed to the counting input of the trigger 5 and to the second inputs of the elements b and 7. Coincidence. pulse on p The output of trigger 5 was 1 (Fig. 2b), and on the inverse O (Fig. 2d), the pulse (Fig. 2e) from the output of the former 4 includes the pulse expander 8. Pulse expander 8 is removed from the pulse expander output. c (Fig. 2g). This pulse through the element OR 10 (Fig. 2i) and the inverter 11 | (Fig. 2k) is fed to the second input of the third matching element 12. A pulse appears at the output of the matching element 12 (Fig. . 2m), the duration of which is equal to the excess of the input signal delayed by the delay element (Fig. 2n) above the value T corresponding to the selection threshold. If the input signal does not exceed the duration t, the signal on the output bus 14 of the device does not appear. A second pulse arriving at the input bus of the device, as well as subsequent even pulses, from the output of the former 4 pulses pass to the input of the element OR 10 through the coincidence element 7 (Fig. 2-) and the expander 9 pulses (Fig. 2h). Short interferences (a sufficiently large amplitude and 4 pulses transmitted to the output of the driver) that appear on the input bus 13 of the device switch the trigger 5 and, starting the expander 9 (or 8) pulses, block the coincidence element 12. If in time t. Before the input signal arrives, two or more interference pulses are possible at the output of the driver 4 pulses, instead of trigger 5, which is a counter with a counting factor equal to two, you need to use a counter with a counting factor equal to the number of possible driver pulses 4 pulses, with the corresponding increase in the number of elements (6, 7) of coincidence and expanders (4) of pulses. Improving the noise immunity provided by the proposed device is particularly important for industrial automation devices operating under elevated electrically; interference. The proposed device is designed for use in a device of fast-speed automatic switching on of backup power used in power supply circuits of industrial enterprises. Formula of the invention. Pulse selector by duration, containing a trigger, the direct and inverse outputs of which are connected to the first inputs of the first and second matches, respectively, the delay element whose input is connected to the input bus of the selector, -a output, to the first input of the third ele coincidence, which differs from the fact that, in order to improve noise immunity, a rectifier, a pulse shaper, first and second pulse expanders, an OR element, an inverter, and a differentiating chain are inputted into it. connected to the selector input bus, and the output through serially connected rectifier and pulse shaper - to the counting trigger input and the second inputs of the first and second coincidence elements, the outputs of which are connected to the inputs of the OR element through the first and second, respectively, pulse extenders connected to the inverter to the second input of the third match item. Sources of information taken into account during the examination 1. USSR author's certificate No. 661760, cl. H 03 K 5/15, 1979. 2. Author's certificate of the USSR. № 440780, cl. H 03 K 5/15, 1975 (prototype).

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Claims (1)

Claim A pulse selector in duration, containing a trigger, the direct and inverse outputs of which are connected to the first inputs of the first and second coincidence elements, a delay element, the input of which is connected to the input selector bus, and the output with the first input of the third coincidence element, distinguishing with the fact that, in order to increase noise immunity, a rectifier, a pulse shaper, the first and second pulse expanders, an OR element, an inverter and a differentiating circuit, the input of which is connected to the input bus with lecturer, and the output through the sequence connected to the second input of the third match element. 15 i