JPH03186772A - Cycle measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a period measuring device capable of measuring the period of a composite periodic waveform, etc., which is a combination of two or more types of periodic waves.

[Prior Art] FIG. 3 is a block diagram showing a conventional period measuring device.
In the figure, 41 is a differentiating circuit that differentiates a periodic wave signal from the outside, 42 is a reference level setter that generates a preset reference level signal, and 43 is a comparator that compares the periodic wave signal and the reference level signal. , 44 is a counter that counts the pulses generated by the oscillator 45 during the period when the comparator 43 outputs a square wave, and 46 is a display that displays a period measurement value corresponding to the number of counted pulses.

The operation of the conventional device configured in this way will be explained.

First, a periodic wave from the outside is differentiated by a differentiating circuit 41, and the differentiated pulse is compared with a reference level signal set by a reference level setter 42 by a comparator 43. This comparator 43 outputs a square wave signal that rises at the same time that the differential value of the periodic wave becomes larger than the reference level. next,
The counter 44 is operated using the rising portion (or falling portion) of this square wave signal as a start signal for the counter 44, and the next rising portion (or falling portion) as a stop signal. Thereby, by counting the number of pulses within the period of the square wave signal, it is possible to measure data corresponding to one period, that is, to measure one period of the human-powered periodic waveform.

[Problem to be solved by the invention] Since the conventional period measuring device is configured as described above, it is easy to measure the period of a single component input periodic waveform, but it is difficult to measure the period of a single component input periodic waveform. There was a drawback that period measurement of composite periodic waveforms could not be performed stably. That is, in the composite periodic waveform, depending on the set value of the reference level, for example, ql-all in FIG. 2 may be erroneously determined as rising or falling. In such a case, there is a problem that the width between the start and stop trigger signals at the rise and fall timings of the square wave is not constant, resulting in unstable period measurement.

The present invention has been made to solve these conventional problems, and an object of the present invention is to provide a period measuring device that can obtain stable and accurate period measurement results even for complex periodic waveforms.

[Means for Solving the Problems] The object of the present invention is to provide intersection detection means for successively detecting intersection points where an input waveform intersects with a reference level; a first subtraction means for calculating a first time interval between the second intersection points and a second time interval between the second intersection point and the third intersection point; and a detection means for the intersection detection means, respectively. The third intersection between the n-th (n is an integer of 3 or more) intersection and the n+1-th intersection
and a fourth time interval between the n+1-th and n+2-th intersection points; a comparison means for detecting whether the difference between the fourth time intervals is within a predetermined value, and the first intersection point and the nth intersection point;
slope direction detection means for detecting whether the directions of the slopes of the input waveforms at the intersection point are the same; and the difference between the two time intervals is within a predetermined value, and the directions of the slopes are the same. This is achieved by a period measuring device characterized in that it is provided with a third subtraction means that calculates the time interval between the first intersection point and the nth intersection point when it is detected that .

[Operation] When the comparison means detects that the difference between the two time intervals is within a predetermined value, and the slope direction detection means detects that the slope directions are the same, the difference between the first to third intersection points is The waveform and the waveform between the n-th and n+2-th intersections are considered to be the same, and these two waveforms are determined to be the first period and the second period, respectively. At this time, the third subtraction means calculates the time interval between the first intersection point and the nth intersection point, and by multiplying this by an appropriate coefficient, the period is displayed.

[Example] Examples of the present invention will be described in detail below.

FIG. 1 is a block diagram showing an embodiment of a period measuring device for input periodic waveforms according to the present invention.

In the figure, 12 is a reference level setter that generates a reference level signal, 13 is a comparator that compares an input periodic waveform such as a composite periodic waveform with the reference level signal, and 14
is a counter that counts the number of pulses generated by the oscillator 15 between adjacent intersections between the input periodic waveform and the reference level; 17 is the slope direction of the input periodic waveform;
In other words, the slope direction detection circuit detects the rising direction or falling direction of the waveform, and 18 is the above-mentioned comparator! The intersection data outputted by 3 is the operating point (trigger signal)
The latch control circuit, 19.20.21, which controls the following latches as shown in FIG.
, P2. This is a latch that holds the pulse count value at P3 and the slope direction of each input cycle.

22, 23, 24 are latches, and each intersection PL, P2 . P
Every time 3 is detected, the output of the latch 24 is input to the latch 23, the output of the latch 23 is input to the latch 22,
And these states are maintained. 25 and 26 are subtracters that subtract the outputs of the adjacent latches +9, 20, and 21.

27 and 28 are subtracters that subtract the outputs of adjacent latches 22, 23, and 24 from each other. 29 is latch 19.2
2 is a slope direction detection circuit that detects whether the slope directions match from the output of 2, and 30 is a subtracter 25.27
31 is an area comparison circuit that compares the outputs of the subtracters 26 and 211.

32 is an AND gate that takes the logical product of the outputs of the slope direction detection circuit 29 and each area comparison circuit 30J1; 33 is a subtracter that performs subtraction between the outputs of the latch 1922 according to the output of the AND gate 32; and 34 is a subtraction of the subtracter 33. This is a display device that displays the results.

In this embodiment, the intersection detection means is the comparator 1
3, the first subtraction means is connected to the subtracter 25.26, the second subtraction means is connected to the subtracter 27.28, the slope direction detection means is connected to the slope direction detection circuit 29, and the comparison means is connected to the area comparison circuit 30.31. and the third subtraction means correspond to the subtracter 33, respectively.

FIG. 2 is a waveform diagram showing an example of a composite periodic waveform measured according to the present invention, and the operation of the periodic measuring device having such a configuration will be explained using the diagram.

First, a composite periodic waveform as shown in FIG. 2 is input to the comparator 13 and compared with, for example, a reference level L set by the reference level setter 12. Next, this comparator I3
Under the control of the latch control circuit 18, the pulse count value measured at the rising and falling edges of the output pulse output by the latches 19.20.2 and the slope direction data detected by the slope direction detection circuit 18 are
Hold at 1.

Here, the operating points of each latch +9, 20, 21 are the intersection points PL, P2. P3
゜... At this time, the latches 22, 23, and 24 input the output of the latch 24 to the latch 23 and the output of the latch 23 to the latch 22 for each operating point of the latch, and maintain their respective states. Furthermore, the latch 24 receives and holds the output value of the counter 14 and the data in the slope direction. Furthermore, the pulse count value at the intersection P1 and data in the slope direction of the composite periodic waveform are input to the latch 19, the pulse count value at the intersection P2 and data in the slope direction are input to the latch 20, and the latch 21 is inputted to the latch 19. The pulse count value and slope direction data at the intersection P3 are input and held respectively.

Next, subtracters 25.26 and 27.28 compare the outputs of adjacent latches 19-21 and 22-24.
Subtract the outputs of . That is, looking at FIG. 2, the subtracter 25 calculates dl=P2-PL, and the subtracter 26
Then, the subtracter 27 calculates d2=P3-P2, and the subtracter 27 calculates d3-P++.
+1−Pn (where n>3), the subtracter 28 calculates d
4=Pn+2-Pn+1, respectively.

These results are input to each area comparison circuit 30.31, and the area comparison circuit 30 calculates d3-di for each area, that is, for each corresponding portion of the same waveform.
The area comparison circuit 31 calculates the absolute value of d4-d2. At this time, the slope direction detection circuit 29 determines whether the data indicating the slope direction held in the latch 19 and the latch 22 are the same. If the slope directions of the AND gates 32 match and the comparison results of the area comparison circuits 30 and 31 fall below the set value, the position of the intersection Pn is the beginning of the second period of the composite periodic waveform. The subtractor 33 is activated. At this time, the subtracter 33 obtains the output difference of the latch 19.22, that is, Pn-PL, and calculates this as a count value for one cycle. The measurement period of the composite periodic waveform thus obtained is converted into frequency data by applying appropriate coefficient processing to the measurement period.

[Effects of the Invention] As explained in detail above, the period measuring device of the present invention has a period measuring device that is configured to measure the time interval between the first and second intersection points where the input waveform and the reference level intersect, and the time interval between the second and third intersection points. Also, calculate the time interval between the n-th and n+1-th intersections and the time interval between the n+1-th and n+2-th intersections, and calculate the difference between these time intervals. By detecting, and further detecting whether the directions of the slopes of the first and nth input waveforms are the same,
Since it is detected whether the waveform from the first intersection point to the third intersection point is the same as the waveform from the nth intersection point to the n+2th intersection point, it is possible to detect two or more types of periodic waves. Even with respect to a composite periodic waveform in which .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a period measuring device according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing a composite periodic waveform measured by the present invention, and FIG. 3 is a block diagram showing a conventional period measuring device. It is. I3...Comparator, slope direction detection circuit, 25-28.33...Subtractor, path. 14...Counter, 17...19~2
4...Latch, 3031...Area comparison time

Claims (1)

[Claims] Intersection detection means for successively detecting intersection points at which an input waveform intersects with a reference level;
a first subtraction means for calculating a first time interval between the second intersection point and the second intersection point and a second time interval between the second intersection point and the third intersection point, and the intersection point detection a third time interval between the n-th (n is an integer of 3 or more) intersection and the n+1-th intersection detected by the means, and the n+-th intersection;
a second subtraction means for calculating a fourth time interval between the first intersection point and the n+2th intersection point, and a difference between the first and third time intervals and a difference between the second and fourth time intervals; Comparing means for detecting whether the differences are within predetermined values, and detecting whether the directions of the slopes of the input waveform at the first intersection point and the n-th intersection point are the same. slope direction detection means, when it is detected that the difference between the two time intervals is within a predetermined value and the directions of the slopes are the same, the first intersection point and the nth intersection point; A period measuring device comprising: third subtraction means for calculating a time interval between periods.