JPH04157374A - Measuring circuit of pulse repetition interval - Google Patents

Abstract

PURPOSE:To enable precise measurement of a pulse repetition interval by dividing a pulse time interval by an integral value of the ratio between an approximate period of an input pulse signal and a plurality of pulse time intervals and by correcting the missing of an input pulse. CONSTITUTION:Based on an interval of first and second pulses of an input pulse signal determined by a pulse interval measuring circuit 1, the respective passing periods of pulse interval filters 3-1 to 3-M in the number of M are set, pulses passing through these filters are counted 4-1 to 4-M and compared by a pulse period detecting circuit 5, a channel wherein a count value is the maximum is selected and an approximate period Tm of the input pulse signal is obtained. The precision of this period Tm is low generally, since it is determined on the basis of a time interval measured from two pulse couples. Therefore a time interval T2 for pulses in the number of N is measured by a pulse interval measuring circuit 2, and the interval T2 is divided by an integral value A determined by rounding one ratio between the interval T2 and the period Tm to the nearest whole number, in a pulse period calculating circuit 6, so as to determine the period of the input pulse signal. By this method, the precision in calculation of a pulse repetition interval can be improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pulse repetition interval measuring circuit.

In particular, the present invention relates to a pulse repetition interval measuring circuit that can accurately measure the original pulse repetition interval even when there is a dropout in the input pulse.

[Conventional technology]

Conventionally, this type of pulse repetition interval measuring circuit has had a configuration as shown in FIG. 2, for example. In FIG. 2, the pulse count circuit 7 counts the number of pulses N of the high-power pulse signal.
Count. moreover.

The pulse interval measuring circuit 8 measures the time interval T from the first pulse counted by the pulse counting circuit 7 to the last pulse. Next, the pulse period calculation circuit 9 calculates the input pulse period using the calculation formula T/N.

[Problem to be solved by the invention]

The conventional pulse repetition interval measuring circuit described above works well as long as there are no omissions in the high-power pulse signal, and the pulse interval measurement accuracy can be improved as the number of pulses counted by the pulse counting circuit increases. I can do it.

However, such a conventional pulse repetition interval measuring circuit has a disadvantage in that the measurement accuracy is greatly degraded when there is a missing pulse in the input pulse signal. especially,
When receiving radio waves propagating in space and determining the pulse repetition period, there is no way to prevent pulse dropouts from occurring, and conventional methods cannot detect the occurrence of pulse dropouts. Correction means cannot be used, which is a drawback in terms of the method.

[Means to solve the problem]

The pulse repetition interval measuring circuit of the present invention includes a first pulse repetition interval measuring circuit that receives an input pulse signal and measures the time interval T1 from the first pulse to the second pulse; From the 1st pulse to the Nth pulse
a second pulse interval measuring circuit that measures the time interval T2 up to the second pulse;

1/M (M
is a positive integer including 1), M pulse interval filters pass only a pulse train having a repetition period of (a positive integer including 1), M pulse counters that count outputs of the M pulse interval filters, and a pulse period detection circuit that inputs a count value of a counter and calculates a repetition period of passing pulses specified by the M pulse interval filters when the count value indicates a maximum, as the approximate period Tm of the input pulse signal; a pulse period calculating circuit which calculates the period of the input pulse signal by dividing the time interval T2 by an integer value A obtained by rounding off the ratio T2/Tm of the time interval T2 and the approximate period Tm. It consists of

Further, in the pulse repetition interval measuring circuit of the present invention, the number M of the pulse interval filters and pulse counters is
It has a configuration in which the pulse repetition interval of the input pulse signal is determined in advance based on a prediction of the magnitude of the pulse dropout frequency in the operational environment in which the pulse repetition interval is measured.

Furthermore, in the pulse repetition interval measuring circuit of the present invention, the number N of pulses necessary for measuring the pulse interval of the input pulse signal in the second pulse interval measuring circuit is determined in advance based on the accuracy required for pulse repetition interval measurement. It has a configuration that

〔Example〕

Next, nine aspects of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention. The embodiment shown in FIG. 1 receives a high-force pulse signal and the time interval T from the first pulse to the second pulse
1, a second pulse interval measuring circuit 2 that measures the time interval T2 from the first pulse to the Nth pulse of the input pulse signal, and a large-force pulse signal. The outputs of M pulse interval filters 3-1 to 3-M and 1M pulse interval filters 3-1 to 3-M, which pass only pulse trains having a repetition period of 1/M of the time interval T1, are counted. M pulse counters 4-1 to 4-M and pulse counters 4-1 to 4-M
The pulse period detection circuit 5 inputs the count value and calculates the pulse repetition period of the maximum count value as the approximate period Tm and the ratio T of the time interval T2 and the approximate period Tm.
The time interval T2 is an integer value A obtained by rounding off 2/Tm.
The pulse period calculation circuit 6 calculates the period of the input pulse signal by dividing the period of the input pulse signal.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

M based on the first and second pulse intervals T1 of the input pulse signal obtained by the first pulse interval measuring circuit 1
The passing period of each of the pulse interval filters 3-1 to 3-M is set, and the settings are sequentially Tl, TI/2. TI/
3...This is the period of TI/M. Therefore, even if there is a pulse dropout between the first and second input pulse signals, T1 is naturally a multiple proportional to the number of dropouts, so the 9M pulse interval filter 3
Any one of -1 to 3-M will have a period that matches the true input pulse repetition.

The pulses that have passed through these M pulse interval filters 3-1 to 3-M are counted by pulse counters 4-1 to 4-M, and the pulse period detection circuit 5 compares the counted values.

In general, even if the pulse loss is below a certain percentage, the number of pulses with the true pulse repetition period of the input pulse signal is large. The value Tm is found.

Since this Tm is a measured value obtained based on the time interval measured between two pulse pairs, the accuracy is generally low if left as is.

Therefore, the second pulse interval measuring circuit 2 measures the time interval T2 for N pulses, and the pulse period calculating circuit 6 averages the number of pulses corrected for the number of missing pulses, thereby improving the accuracy of calculating the pulse repetition interval. let The number of pulses corrected for this number of missing pulses is obtained as a value obtained by rounding off T2/Tm. This is because ITII is a period determined by a circuit system that is not affected by missing pulses, and the decimal part resulting from the calculation of the calculation formula T2/Tm is T.

This is caused by the low precision of , and the integer value obtained by rounding this is the true number of pulses after correcting the number of missing pulses.

In this way, the pulse repetition interval can be calculated with high accuracy.

Note that the number M of pulse interval filters in the configuration of the present invention
is determined depending on the degree of omission in the input pulse signal. That is, in the case of an operational environment in which the frequency of loss is expected to be low, 9M is designed in advance to be as small as about 2 to 3, and when the frequency of loss is high, M is designed to be large.

Further, the number N of input pulse signals necessary for calculating T2 measured by the second pulse interval measuring circuit 2 is determined according to the required accuracy, and the larger N is, the more the accuracy is improved by averaging. In this way, the accuracy is the same as that of the conventional method when there are no omissions, and even when there are omissions, the accuracy can be maintained.

〔Effect of the invention〕

As explained above, even in the case of an input signal in which pulse dropouts occur at a certain rate, the present invention roughly measures the true period of the part where pulse dropouts do not occur, and then calculates the rough measurement results. By correcting the pulse loss of the input pulse based on R, it is possible to measure the pulse repetition interval with high accuracy by finally averaging.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the pulse repetition interval measuring circuit of the present invention, and FIG. 2 is a block diagram showing the configuration of a conventional pulse repetition interval measuring circuit. DESCRIPTION OF SYMBOLS 1... First pulse interval measuring circuit, 2... Second pulse interval measuring circuit, 3-1 to 3-M... Pulse interval filter, 4-1 to 4-M... Pulse counter . 5... Pulse period detection circuit, 6... Pulse period calculation circuit, 7... Pulse count circuit, 8... Pulse interval measurement circuit, 9... Pulse period calculation circuit.

Claims (1)

[Claims] 1. A first pulse interval measuring circuit that receives an input pulse signal and measures the time interval T1 from the first pulse to the second pulse; a second pulse interval measuring circuit that measures the time interval T2 from the pulse to the Nth pulse; and a repetition period of 1/M (M is a positive integer including 1) of the time interval T1 from the input pulse signal. M pulse interval filters that pass only a pulse train having a value of a pulse period detection circuit that determines a passing pulse repetition period specified by the M pulse interval filters as the approximate period T_m of the input pulse signal; and a ratio T of the time interval T2 and the approximate period T_m;
2/T_m divided by an integer value A obtained by rounding off the time interval T2 to obtain a value T2/A as the period of the input pulse signal. measurement circuit. 2. The number M of the pulse interval filters and pulse counters is determined in advance based on a prediction of the magnitude of pulse dropout frequency in the operating environment in which the pulse repetition interval measurement of the input pulse signal is performed. The pulse repetition interval measuring circuit according to item 1. 3. A claim characterized in that the number N of pulses necessary for measuring the pulse interval of the input pulse signal in the second pulse interval measuring circuit is determined in advance based on the accuracy required for measuring the pulse repetition interval. The pulse repetition interval measuring circuit according to item 1.