JP3077187B2 - Pulse repetition interval measurement circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse repetition interval measuring circuit, and more particularly to a circuit capable of accurately measuring an original pulse repetition interval even when an input pulse is missing. The present invention relates to a pulse repetition interval measuring circuit.

[Conventional technology]

Conventionally, this kind of pulse repetition interval measuring circuit has, for example, a configuration as shown in FIG. In FIG. 2, a pulse counting circuit 7 counts the number N of pulses of the input pulse signal. Further, 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 input pulse period is obtained by the pulse period calculation circuit 9 using the calculation formula T / N.

[Problems to be solved by the invention]

The above-described conventional pulse repetition interval measurement circuit operates well if there is no dropout in the input pulse signal, and the pulse interval measurement accuracy can be improved by setting a larger number of pulses to be counted by the pulse count circuit. .

However, there is a disadvantage that the measurement accuracy is greatly deteriorated when a pulse is missing in the input pulse signal of such a conventional pulse repetition interval measuring circuit. In particular,
When receiving a radio wave propagating in space and calculating the pulse repetition period, it is unavoidable to prevent the occurrence of a pulse drop, and the detection of the pulse drop cannot be detected by the conventional method. A means such as correction cannot be used, which is a drawback in the system.

[Means for solving the problem]

A pulse repetition interval measurement circuit according to the present invention includes: a first pulse interval measurement circuit that receives an input pulse signal and measures a time interval T1 from a first pulse to a second pulse;
A second pulse interval measurement circuit for measuring a time interval T2 from the first pulse to the Nth pulse of the input pulse signal, and 1/1/3 of the time interval T1 from the input pulse signal
M pulse interval filters for passing only pulse trains having a repetition period of M (M is a positive integer including 1), M pulse counters for counting the outputs of the M pulse interval filters, pulse period detecting circuit for obtaining pieces of the count value by inputting the count value of the pulse counter is the passing pulse repetition period specified by the M pulse interval filter shows a maximum as schematically period T _m of a said input pulse signal When integer values a obtained by rounding off the ratio T2 / T _m of the said time interval T2 schematic period T _m
And a pulse cycle calculation circuit for calculating the cycle of the input pulse signal by a value T2 / A obtained by dividing the time interval T2.

Further, the pulse repetition interval measuring circuit of the present invention comprises the pulse interval filter and the pulse counter M
Has a configuration in which the pulse repetition interval of the input pulse signal is measured and the pulse repetition frequency is determined in advance in the operating environment based on the prediction of the magnitude of the pulse drop frequency.

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

〔Example〕

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

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In the embodiment shown in FIG. 1, the input pulse signal is received and the time interval T1 from the first pulse to the second pulse is obtained.
From the input pulse signal, a first pulse interval measurement circuit 1 for measuring the input pulse signal, a second pulse interval measurement circuit 2 for measuring the time interval T2 from the first pulse to the Nth pulse of the input pulse signal, M pulse interval filters 3-1 to 3-M that pass only pulse trains having a repetition period of 1 / M of the time interval T1, and M pulse interval filters 3-1 to 3-3
-M pulse counters 4-1 for counting the output of -M
And to 4-M, a pulse period detecting circuit 5 to determine the pulse repetition period of the count value by inputting the count value of the pulse counter 4-1 to 4-M are those showing a maximum as schematically period T _m, the time interval T2 A pulse period calculating circuit 6 for dividing the time interval T2 by the integer value A obtained by rounding off the ratio T2 / _Tm of the approximate period _Tm and obtaining the period as the period of the input pulse signal.

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

M based on the first and second pulse intervals T1 of the input pulse signal obtained by the first pulse interval measurement circuit 1
Each pass period of the pulse interval filters 3-1 to 3-M is set, and the setting is in the order of T1, T1 / 2, T1 / 3... T1 / M. Therefore, even if pulse loss occurs between the first and second input pulse signals, T1 is naturally a multiple proportional to the number of missing pulses.
One of the M pulse interval filters 3-1 to 3-M has a period that matches the true input pulse repetition. These M pulse interval filters 3-1 to 3-1
The pulses that have passed through 3-M are output to pulse counters 4-1 to 4
-M, and the pulse period detection circuit 5 compares the count values.

In general, if the pulse loss is below a certain ratio, the number of pulses having a true pulse repetition period of the input pulse signal is large. The value T _m is known.
Since this _Tm is a measurement value obtained based on the time interval measured with two pulse pairs, the accuracy is generally low as it is.

For this reason, the second pulse interval measurement circuit 2 measures the time interval T2 for N pulses, and the pulse period calculation 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 it. The number of pulses corrected for the number of the missing pulses is determined as a value obtained by rounding off T2 / T _m. The reason is that _Tm is a period obtained by a circuit method which is not affected by the missing pulse, and the calculation formula T2
The decimal part resulting from the calculation of / T _m is caused by the low precision of T _m , and the rounded integer value is the true pulse number corrected for the missing pulse number.

Thus, the pulse repetition interval can be accurately calculated.

Note that the number M of pulse interval filters in the configuration of the present invention is determined according to the degree of missing in the input pulse signal. That is, in an operating environment where the frequency of dropouts is expected to be small, M is designed in advance to be small to about 2 to 3 and to be large when the dropout frequency is high.
In addition, the number N of input pulse signals required for calculating T2 measured by the second pulse interval measurement circuit 2 is determined according to the required accuracy, and the accuracy is improved by averaging as N is increased. In this way, the accuracy is the same as that of the conventional method in which there is no loss, and the accuracy can be maintained even if there is a loss.

〔The invention's effect〕

As described above, according to the present invention, even when an input signal in which a pulse loss occurs at a certain rate, the true period of a portion where no loss occurs is roughly measured, and then the rough measurement result is obtained. By correcting missing pulses of the input pulse based on the above, there is an effect that the pulse repetition interval can be measured with high accuracy by finally performing averaging.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a pulse repetition interval measuring circuit according to the present invention, and FIG. 2 is a block diagram showing a configuration of a conventional pulse repetition interval measuring circuit. 1 first pulse interval measurement circuit, 2 second pulse interval measurement circuit, 3-1 to 3-M ... pulse interval filter, 4-
1 to 4-M pulse counter, 5 pulse cycle detection circuit, 6 pulse cycle calculation circuit, 7 pulse count circuit, 8 pulse interval measurement circuit, 9 pulse cycle calculation circuit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 29/02-29/033 G01R 23/02-23/15 G01S 7/40

Claims (3)

(57) [Claims] A first pulse interval measuring circuit for receiving an input pulse signal and measuring a time interval T1 from a first pulse to a second pulse; and a first pulse interval measuring circuit for measuring a time interval T1 from the first pulse of the input pulse signal. A second pulse interval measuring circuit for measuring a time interval T2 up to the Nth pulse, and a pulse train having 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 only pass through, M pulse counters that count the outputs of the M pulse interval filters, and the count values of the M pulse counters are input to increase the count value to the maximum. a pulse period detecting circuit for obtaining a passing pulse repetition period specified by the M pulse interval filter shows a schematic period T _m of a said input pulse signal, and the time interval T2 Serial schematic period T _m of a ratio T2 / T _m obtained by dividing the time interval T2 an integer value A obtained by rounding off the value T2
A pulse cycle calculating circuit for determining / A as a cycle of the input pulse signal. 2. The method according to claim 1, wherein the number M of the pulse interval filters and pulse counters is determined in advance based on the prediction of the magnitude of the pulse drop frequency in an operating environment for measuring the pulse repetition interval of the input pulse signal. The pulse repetition interval measuring circuit according to claim 1, wherein 3. The pulse number N required for measuring a pulse interval of an input pulse signal in the second pulse interval measuring circuit is:
2. The pulse repetition interval measurement circuit according to claim 1, wherein the pulse repetition interval measurement circuit is determined in advance based on the accuracy required for the pulse repetition interval measurement.