SU1749851A1 - Method of pulse selecting in duration and device for realization - Google Patents

Abstract

The invention relates to a pulse technique and can be used in a pulse signal processing apparatus. Summary of the Invention: according to the pulse selection method, by duration, they fix n instantaneous voltage values of the input signal at certain time intervals during the time interval T corresponding to the threshold of the selected durations, compare the recorded values with each other and make a decision about the duration of the input pulses according to the comparison result, the intervals the time between readings is selected with a variable duration varying in time according to a periodic law with a repetition rate equal to or second multiple of 1 / T, device 1 comprises a shift register, a function generator 2, the generator 3 sync monostable multivibrator 4, AND gate 5 with the respective linkages. 2 sec. and 1 z.p. f-ly, 1 ill. in

Description

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The invention relates to a pulse technique and can be used in a pulse signal processing apparatus.

There is a method for selecting pulses by duration, which consists in fixing n samples of the input signal level at equal reference time intervals and deciding whether the duration threshold is exceeded when all n samples are equal to logic level 1, and if the input signal level is equal to logical O, the previous time n samples are zeroed, and a device for implementing this method, comprising a clock generator, a shift register, and element I.

The closest to the proposed technical solutions are the method of pulse selection by duration, which consists in fixing n instantaneous values of the input signal voltage at equal certain time intervals during the time interval T corresponding to the threshold of selectable durations, comparing the recorded values between themselves and deciding the duration of the input pulses according to the result of the comparison, and a device for its implementation, comprising a clock generator, a shift register and an element t I.

A disadvantage of the known method and device is the low noise immunity when exposed to periodic pulsed noise, coinciding with the moments of the input signal level readings.

The purpose of the invention is to improve noise immunity by eliminating the influence of periodic impulse noise, which coincides with the moments of the input signal level readings.

According to the pulse duration selection method, n instantaneous values of the input signal voltage are fixed at certain time intervals during the time interval T corresponding to the threshold of selectable durations, the recorded values are compared and the decision on the duration of the input pulses is compared according to the result of the comparison, the time interval between samples choose a variable duration varying in time according to the periodic law iy with a repetition rate equal to or a multiple of 1 / T,

 la chrr. also shows a block diagram of a device that implements a method for selecting pulses in duration.

The device contains a shift register 1. serially connected function generator 2 and generator 3 of clock pulses, the output of which is connected to the synchronization input of the shift register 1, one-oscillator 4 and element 5, whose inputs

connected to the output of the one-shot A and the bit outputs of the shift register 1, whose information input is the device input 6, the input of the one-shot 4 is connected to the output of the generator 3 clock pulses.

The device works as follows.

Functional generator 2 produces a signal at its output, amplitude

which is a function of time defining the law of change of reference time intervals. The repetition rate of this function is equal to or a multiple of 1 / T, where T is the threshold value of the input duration

pulses. For example, when changing the time intervals between samples of the input signal level in accordance with a triangular function, the signal at the output of generator 2 is described by the following expression:

f Ao (t-iT), with IT t (1 + 1/2) T

S2 (t)

L AoKO + 1) T-t), with (i + 1/2) T t (i + 1) T, where, 1, 2, ... is a non-negative integer;

AQ-constant normalization factor.

The generator 3 clock pulses generates clock pulses, the repetition period of which is 07n-H (S2 (t) -Ao / 2)) / m), where k is the slope of the frequency modulation of the clock pulses; n is the number of bits of shift register 1; m is a positive integer.

For normal operation, the condition must be met.

kAo "T / n. The repetition frequency of clock pulses is equal to or a multiple of m times the value of 1 / T.

Shift register 1 fixes the input signal level input to input 6 at the time of forming the leading edges of the clock pulses and stores them in sequence.

When exceeding the duration of the input pulse threshold value T

0 selectable duration in all bits of the shift register 1, the potentials of logical G will be recorded. At the moment of appearance at the output of the one-shot 4 pulses at the output of the element I 5,

5 impulse of registration of exceeding the threshold of selection of the pulse duration A single vibrator 4 generates pulses, the leading fronts of which coincide with the trailing edges of the sync pulses. The duration of the sync pulses and pulses at the output of the one-shot 4 must be less than the value T / 2n "m. The most gating pulses at the input of the element And 5, produced by the single vibrator 4, are necessary to eliminate the appearance at the output of the device of false recording pulses at the moments of the shift of the sampling signals recorded in the register 1.

When the duration of the input pulse is less than the threshold of the selected duration T at least one of the first or last bits of the shift register 1, the next reading of the input signal level equal to the potential of logic O will be recorded. In this case, the registration pulse does not appear at the output of the And 5 element.

A positive effect when using the proposed method and device as compared with the known technical solution is that when a periodic impulse noise appears at the input, the probability of coincidence of the leading edges of sync pulses with the presence of noise decreases, which is achieved by introducing frequency modulation of the sync pulses.

Claims (3)

Invention Formula 1, Method for selecting pulses in duration, according to which they fix n instantaneous values of the voltage of the input signal at certain time intervals during the time interval T corresponding to the threshold selectable durations, compare the recorded values between each other and compare the result of the duration of the input pulses, characterized in that, in order to improve the noise immunity by eliminating the influence of periodic impulse noise, coinciding with the time counts of the input signal level, the samples are selected with a variable duration varying according to a periodic law with a repetition rate equal to or a multiple of 1 / T. 2. Method pop. 1, characterized in that the law of variation of time intervals is described by a triangular function of time. 3. A device for the selection of pulses in duration, containing a generator clock pulses, a shift register, a single vibrator, and an element, whose inputs are connected to the bit outputs of the shift register and a single vibrator output, the input of which is connected to the output of the siphro pulse generator and the input of the synchronization of the shift register, whose information input is the input of the device, characterized in that , in order to improve noise immunity by eliminating the influence of periodic impulse noise interfering with the moments of the readings of the level of a similar signal, a functional generator was introduced, the output of which is connected to the input of the clock pulse generator.