JP3145525B2 - Burst wave frequency measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the frequency of a burst wave using an electronic counter.

[0002]

2. Description of the Related Art A frequency measurement method using an electronic counter basically counts the number of vibrations per unit time. Conventionally, for this purpose, the measured wave is first amplified and shaped, converted into a pulse signal train, the gate is opened and closed at a reference time, and the number of pulse signals passing through the gate while the gate is open is counted by an electronic counter. Frequency was calculated and displayed.

The gate open time is generally 1 ms, 1 ms generated by dividing the frequency from the reference frequency of 10 MHz of the crystal oscillator.
The reference time, such as 0 ms, 100 ms, 1 s, and 10 s, is defined as a unit.

In the case of an intermittent burst wave in which the length of a signal also changes, such as a pulse-modulated wave or a carrier frequency of an intermittent wave, the gate is opened when there is no signal so that measurement is not started. To this end, the measured wave is converted into a pulse signal and the measured wave is detected, and the gate is opened at a reference time shorter than its duration while its level is higher than a predetermined value.

[0005]

In each of the above conventional measuring methods, a fixed time of, for example, 1 μs, 10 μs,... 10 s is counted once for each burst wave. Elevation required counting for a number of waves and the measurement took a long time.

In order to solve this problem, a method of counting the pulse signal by extending the gate open time as long as the pulse signal exists, that is, not only opening the gate but also closing the gate, is a detection envelope of a burst wave. A method was attempted in which the reference time was changed according to the duration of the wave in synchronization with the falling edge of the wave.

However, it is easy to open the gate by detecting that the level of the envelope becomes a predetermined value, but if the gate is closed by detecting that the level has become lower than the predetermined value, It is possible that there is no signal before the gate closes.

There is also a method of providing a signal even after the gate is closed with a delay. However, the rise and fall times of the burst wave are not always fast, and several hundred μs to
Since it takes several ns, it is difficult to set a delay time.

Although there is a method of separately providing an external gate for making a variable reference gate and performing measurement, it is not practical to provide a separate external gate.

Therefore, the relationship between the count value of the pulse signal and the number of times corresponding to the pulse signal does not match, and there is a drawback that an error occurs in the frequency calculated and displayed.

An object of the present invention is to provide a method of measuring the frequency of a burst wave which can solve the above-mentioned drawbacks and can obtain a measured value with a small error in a short time measurement.

[0012]

According to the method of measuring the frequency of a burst wave according to the present invention, a pulse signal is counted for each short reference unit time determined while the gate is open, starting from when the gate is open. The count value of the pulse signal is written into the memory, the count value within the reference unit time being counted when the gate is closed is invalidated, and the count value written into the memory and the count value are written to the memory except for the invalidated count value. The frequency of the measured wave is calculated based on the number of times of writing.

[0013]

The count value of one wave, which was conventionally obtained only by the count value of one total sum, is divided into a plurality of count values for each short reference unit time, and the gate is closed to reduce the count value to the reference unit time. The frequency is calculated excluding the pulse count value in the time period less than the time period.

[0014]

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

FIG. 1 is a block diagram of an embodiment of a measuring circuit for implementing the method of measuring the frequency of a burst wave according to the present invention, and FIG. 2 is a timing chart of the embodiment of FIG.

In FIG. 1, a measuring circuit according to the present embodiment includes a converter 10 for shaping a burst wave to be measured and converting it into a pulse signal, and a gate for detecting the burst wave and keeping its level at or above a predetermined value. A detection unit 20 for generating an open signal; a reference time generation unit 30 for setting one of fixed reference unit times of 1 μs to 10 s corresponding to a burst wave to be measured; a conversion unit 10; And the respective outputs of the reference time generation unit 30 to receive three types of synchronization signals MG1 and MG
2 and C, and two main gates 4 that receive the pulse signal output from the converter 10 and one of the synchronization signals MG1 and MG2 and output a logical sum thereof.
1, 42, two counters 51, 52 for counting the number of pulses output from the main gates 41, 42, respectively, a transfer clock 60 for transferring the synchronization signal C, and counters 51, 5
2, a memory 70 for writing the data of the count value from 2, a calculation unit 80 for calculating the average frequency and average period of the measured burst wave from the data written in the memory 70, and a calculation unit 8
And a display unit 90 for displaying 0 output data.

The synchronizing signals MG1 and MG2 are signals that alternately turn on and off by a set reference unit time while the gate opening signal is output. The synchronizing signal C is a signal for which the gate opening signal is output. It is issued every reference unit time set from time to time, that is, every time one of the two counters 51 and 52 counts, and is not issued after the gate open signal is turned off.

A burst wave is inputted by this measuring circuit.
When measuring the frequency, as shown in Fig. 2,
Synchronous gate by gate open signal issued from unit 20
40 is activated and the base time generated by the reference time generation unit 30
Alternate to main gates 41 and 42 every semi-unit time MG0
To the synchronization signals MG1 and MG2. Each main gate 4
1, 42 are output while the synchronization signal MG1 or MG2 is on.
The pulse signal input from the conversion unit 10 is converted into each of the counters 51 and 5.
2 and the counters 51 and 52 respectively
Number M of transferred pulse signals₁ , M_Three , ... M_N-1 Or
M_Two , M_Four , ... M _N Is counted, its count value and count times
The number of data is stored in the memory 70. However, the gate
When the release signal turns off, the reference unit time is not reached
The (N + 1) th data is a synchronization signal corresponding to a transfer command.
Since C is not issued, it is not transferred to the memory 70,
It works. The arithmetic unit 80 stores the data stored in the memory 70.
From the sum of the count values (M₁ + M_Two + ... + M_N ) / (Measurement times
(Number N) × (reference unit time)
The average frequency of the wave is calculated, and this is displayed on the display unit 90.
You.

When measuring the period of the wave to be measured, such as the interval between adjacent burst waves, a pulse signal of a standard clock is input from a portion corresponding to the converter 10 and a gate is opened and closed from a portion corresponding to the detector 20. When an instruction signal is generated and input, a pulse signal of the standard clock is counted by dividing the gate open period for each reference unit time as in this embodiment, and the average period can be measured.

In this embodiment, two counters 51,
52, the data transfer from the other counter to the one memory 70 is repeated while the other counter is measuring, so that the time during which the gate is open is divided by the reference unit time to perform continuous measurement. ing. However, when the reference unit time as a unit is short and the transfer process cannot be completed within this time, the number of counters and memories may be increased to use them cyclically.

A comparison between the conventional measuring method and the present embodiment shows that
Conventionally, the total count value (M
_{1 to} M _{N + 1} ) or separately determined count values in a unit time, that is, one count value is obtained for each wave to obtain (N + 1) times the unit time or the unit time. Frequency. However, in this embodiment, one wave is divided by the reference unit time and counted N + 1 times by two counters, and N + 1 less than the reference unit time is counted.
Th of the count value of the time zone M _{N + 1} with the exception of the N-number of the count value M ₁
Since the sum of ~M _N is divided by N times the reference unit time is the average frequency, not only an incomplete count M _{N + 1} is removed, the standard deviation from the count value of one wave, dispersion, etc. Can be obtained, and the resolution can be increased by a short measurement.

[0022]

As described above, according to the present invention, the pulse signal is counted every predetermined short reference unit time during the gate opening time,
By calculating the frequency excluding the incomplete count value when the gate is closed, a large number of count value data with few errors can be obtained in a short measurement time, and the frequency of the burst wave can be measured with high resolution.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a measurement circuit for implementing the present invention.

FIG. 2 is a timing chart of the embodiment of FIG.

[Explanation of symbols]

 Reference Signs List 10 conversion unit 20 detection unit 30 reference time generation unit 40 synchronization gate 41, 42 gate 51, 52 counter 60 transfer clock 70 memory 80 operation unit 90 display unit

Claims (1)

(57) [Claims] 1. A waveform to be measured is shaped and then converted into a pulse signal train. The waveform to be measured is detected, and a gate is opened and closed in synchronization with the rise and fall of the waveform, and passes while the gate is open. In the method of measuring the frequency of the burst wave by an electronic counter that calculates and displays the frequency of the wave under measurement based on the count value and the gate opening time, the pulse signal is calculated based on the counted value and the gate opening time. The pulse signal is counted for each reference unit time, the count value of the pulse signal for each reference unit time is written to the memory, and the count value of the reference unit time zone that is being counted when the gate is closed is already in the memory by then. All written counts,
A frequency measurement method for a burst wave, wherein a frequency of a wave to be measured is calculated based on a length of a reference unit time.