SU440780A1 - Device for the selection of pulses in duration - Google Patents

Description

one

This invention relates to the field of digital computing and automation.

Pulse selection devices are known, comprising a trigger, a pulse counter, a delay line and a coincidence circuit, the first input of which is connected to the output of the delay line and the second to the input of the delay line.

Such devices are characterized by the presence of spurious signals at the output when, for example, the follow-up period is less than the selection threshold (for a pulse selector of maximum duration). With some characteristics of the flow of input pulses, the number of spurious signals at the output of the device may even exceed the number of input pulses, the duration of which is longer than the selection threshold, and the construction of such a selector becomes generally impractical.

Constructing a pulse selector in terms of duration, the output of which does not contain spurious signals, that is, a selector whose functionality is higher with respect to the input pulse stream, is of great practical importance, for example, in determining various likelihood characteristics of pulse signals.

To improve the reliability of pulse selection, the output of the delay line is connected via a serially connected trigger.

the keys and the counter with the third input of the coincidence circuit, the control input of the first key and the counting input of the trigger are connected to the input of the delay line, and the control input of the second key and the zero reset input are connected to the output of the delay line.

FIG. 1 shows a block diagram of the device; in fig. 2 - time diagrams of voltages.

A device for selecting pulses in duration contains a delay line 1, a trigger 2, controllable keys 3 and 4, a counter 5 and a coincidence circuit 6. In this case, a trigger 2, controllable keys 3 and 4 and a counter 5 are connected in series, the input and output lines delays 1 are connected to trigger inputs 2, signal inputs of keys 3 and 4, and inputs of a matching circuit 6, one of the inputs of which is connected to the output of counter 5.

Ustorshtvo works as follows.

The input pulses are successively (see Fig. 2) fed to delay line 1, the value of which determines the selection threshold, c to the signal input of the coincidence circuit 6. The pulses delayed by time t from the output of the delay line 1 pass to another signal input of the coincidence circuit b (see Fig. 26).

Pulse selection is carried out as follows. When a pulse arrives at the device input with a duration less than the selection threshold, it arrives at the signal inputs of circuit 6 at different times and does not coincide. If, then, at some part of the input pulse, namely, from moment to moment, the signal is present at both signal inputs of the coincidence circuit, so that a pulse of duration n - m appears at its output (see Fig. 2c).

In the process of selecting pulses in terms of duration, there may be a situation, resulting in the appearance of spurious signals at the output of the selector. This occurs when the input pulse coincides in time with one of the previous delayed (false pulses are shown by the dotted line in Fig. 2c). To avoid this, in the proposed device a prohibition signal is generated for the time between the fall of the input signal and the delay of the delayed, therefore only the output signal of the input pulse with the corresponding delayed signal passes to the output of circuit 6.

The prohibition signal is generated using trigger 2, keys 3, 4, and counter 5. By dropping the first input signal, the trigger is set to unlock key 4, and the analyzed pulses are passed to the forward input of counter 5, which counts the number of their decays, including the decay of the first input signal. At the same time, a signal appears at the output of the counter (see Fig. 2d), blocking the coincidence circuit 6. After a certain interval t, the first pulse appears at the output of the delay element and during a fall, trigger 2 returns to its initial state, blocking key 4 and unlocking key 3

Thus, counter 5 counts the number N of pulse decays present in the interval t from the time of the fall of the first analyzed pulse, including

this recession.

When the key 3 is unlocked, the delayed pulses pass to the inverted input of counter 5, so that the delayed pulses begin to be subtracted from the number N stored in the counter. When the number of delays of the delayed pulses, including the fall of the first signal, reaches the number N, the counter returns to the zero initial state, and match 6 will be unlocked.

The capacitance of the counter must be at least iNwaKc t / max, where / max is the maximum frequency of the input pulses.

Subject invention

A device for selecting pulses by duration, comprising a trigger, a pulse counter, a delay line and a coincidence circuit, the first input of which is connected to the output of the delay line and the second input to the input of the delay line, characterized in that, in order to increase the reliability of pulse selection, the output line connection delays through a serially connected trigger, keys and a counter with the third input of the coincidence circuit; the control input of the first key and the count input of the trigger are connected to the input of the delay line, and the control input of the second the key and the trigger reset input are connected to the output of the delay line.

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