JP2010216925A - Data recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data recording device capable of suppressing a data recording amount while reliably recording fine variation of a waveform and easily detecting an abnormal variation part of the waveform after the recording. <P>SOLUTION: In the data recording device converting an analog input signal to digital data by an A/D converter and storing it into a data memory, an extreme point detection part detecting an extreme point of the analog input signal on the basis of the digital data converted and output from the A/D converter is provided between the A/D converter and the data memory. The extreme point data in which a waveform data value of each detected extreme point and the number of sampling times between the extreme points are paired are stored in the data memory. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a data recording apparatus, and more particularly to improvement of data recording when an abnormality occurs.

  FIG. 6 is a block diagram showing an example of a conventional data recording apparatus. The analog input waveform is input to the input unit 1, adjusted to an amplitude suitable for A / D conversion operation, and input to the A / D converter 2.

  The A / D converter 2 converts the analog input waveform into digital data according to the frequency of the sample clock input from the clock generator 3, and stores the converted digital data in the data memory 4. For example, when the frequency of the sample clock is 10 kS / s, the A / D converter 2 performs sampling 10,000 times per second.

  The digital data stored in the data memory 4 is read out to the waveform display unit 5 and displayed as a measurement waveform. The analog input waveform can be confirmed from the waveform displayed on the display screen of the waveform display section 5.

  FIG. 7 is an explanatory diagram of the operation of FIG. 6, (A) shows an example of recording a high sample point when the sample clock frequency is set high, and (B) shows a low sample clock frequency (1/5 of A). ) An example of recording a low sample point when set is shown.

  According to the high sample point recording example of (A), the data sampling of the analog input waveform is performed at a short interval, so that a minute fluctuation state of the waveform can be converted into digital data and taken into the data memory 4 to obtain the waveform. Abnormalities (unusual waveform fluctuations) can be reproduced and displayed.

  On the other hand, according to the low sampling point recording example of (B), since the data sampling of the analog input waveform is performed at a long interval, the fine fluctuation state of the waveform is buried in the sampling valley. Cannot be converted into the data memory 4 and cannot be reproduced and displayed.

  FIG. 8 is an example of sample data in the apparatus of FIG. 6, (A) shows an example of high sample point data when the sample clock frequency is set high, and (B) shows a low sample clock frequency (of A 1/5) An example of low sample point data when set is shown. Since the clock frequency of (A) is five times that of (B), the high sample point data amount is five times the low sample point data amount.

  Patent Document 1 relates to a recorder using recording paper. When an abnormality of an input signal is detected, the recording paper feed speed is made higher than the normal state and the sampling frequency is made higher than the normal state. Thus, it is described that the abnormal state of the input signal is finely recorded on the recording paper and the consumption of the recording paper is reduced.

No. 1-245568

  However, according to the high sample point recording, a finer waveform fluctuation can be recorded, but the amount of data to be recorded increases, and a large amount of memory is used.

  In addition, an abnormal waveform portion of a waveform must be detected from a large amount of data, and there is a problem that it takes time for data processing.

  On the other hand, the low sample point recording can reduce the amount of data to be recorded as compared with the high sample recording, but cannot detect a minute change in the waveform and cannot detect the waveform abnormality.

  The present invention solves these problems, and its purpose is to reduce the amount of recorded data while reliably recording minute fluctuations in the waveform, and to easily detect abnormal fluctuation portions of the waveform after recording. It is an object of the present invention to provide a data recording apparatus that can be used in the future.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In a data recording apparatus configured to convert an analog input signal into digital data by an A / D converter and store the digital data in a data memory,
An extreme point detection unit for detecting an extreme point of an analog input signal based on digital data converted and output from the A / D converter is provided between the A / D converter and the data memory,
The data memory stores extreme point data in which the waveform data value of each detected extreme point and the number of samplings between extreme points are paired.

The invention according to claim 2 is the data recording apparatus according to claim 1,
The extreme point detection unit includes a differential calculation unit that calculates a slope of the analog input signal based on digital data converted and output from the A / D converter, and a sign of the slope of the analog input signal calculated by the differential calculation unit It is characterized by comprising a zero-cross point detector for detecting the position where the rotation is reversed.

The invention according to claim 3 is the data recording apparatus according to claim 1 or 2, wherein
A smoothing processing unit that removes a noise component of the analog input signal is provided in a preceding stage or a subsequent stage of the A / D converter.

The invention according to claim 4 is the data recording apparatus according to claim 3,
The smoothing processing unit is a low-pass filter.

  According to the present invention, it is possible to suppress the amount of recorded data while reliably recording minute fluctuations in the waveform, and it is possible to easily detect abnormal fluctuation portions of the waveform.

It is a block diagram which shows an example of embodiment of this invention. It is operation | movement explanatory drawing of FIG. It is an example figure of the sample data in the apparatus of FIG. It is operation | movement explanatory drawing in the case of sampling-recording the sine wave of 1 period T = 1 second by the sample clock 10 kS / s. It is an example figure of sample data of FIG. It is a block diagram which shows an example of the conventional data recording device. It is operation | movement explanatory drawing of FIG. It is an example figure of the sample data in the apparatus of FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of an embodiment of the present invention. Components identical with those in FIG. The difference between FIG. 1 and FIG. 6 is that, in FIG. 1, an extreme point detector 6 is provided between the A / D converter 2 and the data memory 4.

  In FIG. 1, an analog input waveform is input to an input unit 1, adjusted to an amplitude suitable for A / D conversion operation, and input to an A / D converter 2.

  The A / D converter 2 converts the analog input waveform into digital data according to the frequency of the sample clock input from the clock generator 3, and outputs the converted digital data to the extreme point detection unit 6. For example, when the frequency of the sample clock is 10 kS / s, the A / D converter 2 performs sampling 10,000 times per second.

  The extreme point detection unit 6 includes a differential calculation unit 61 and a zero cross point detection unit 62. In the extreme point detection unit 6, the differential calculation unit 61 obtains the slope of the waveform based on the waveform data sampled by the A / D converter 2. The zero cross point detector 62 detects a position (zero cross point) where the sign of the slope of the waveform obtained by the differential calculator 61 is reversed.

  Then, the detected waveform data value of each extreme point and the number of samplings between extreme points are paired and stored in the data memory 4 as extreme point data.

  The extreme point data stored in the data memory 4 is not at regular intervals in time. Therefore, time information of adjacent extreme points is acquired from the sampling frequency data between extreme points recorded as a pair, and the waveform is interpolated and reproduced and displayed on the waveform display unit 5. The analog input waveform can be confirmed from the waveform displayed on the display screen of the waveform display section 5.

  Note that high-frequency components such as noise may be added to the waveform. In this case, if necessary, an appropriate extreme point can be obtained by providing a smoothing processing unit made of, for example, a low-pass filter in the input unit 1 in the preceding stage of the A / D converter 2 to remove noise components. Can do. The smoothing processing unit may be provided after the A / D converter 2.

  FIG. 2 is a diagram for explaining the operation of FIG. The extreme point detection unit 6 detects an extreme point from waveform data obtained by sampling the analog input waveform indicated by the solid line by the A / D converter 2 at the same frequency as the high sample point recording, and stores it in the data memory 4.

  Although the waveform data recorded as extreme point data cannot reproduce the waveform fluctuation between the extreme point points, the waveform data recorded at the point C and point D are recorded without missing.

  In waveform reproduction, time information of adjacent extreme points is acquired from sampling number data between extreme points of extreme point data stored as a pair in the data memory 4, and a line segment between extreme points is indicated by a broken line. As shown in Fig. 5, the waveform is displayed on the waveform display unit 5 by interpolation. An analog input waveform can be confirmed by an approximate waveform composed of an extreme point displayed on the display screen of the waveform display unit 5 and an interpolation line connecting the extreme points.

  FIG. 3 is an example of sample data in the apparatus of FIG. 1, (A) shows an example of high sample point data when the sample clock frequency is set high, and (B) shows a low sample clock frequency (A 1/5) An example of low sample point data when set is shown, and (C) shows an example of extreme point data based on the present invention.

  High sampling point recording and low sampling recording are “sampling count = recording data score”, but extreme point recording according to the present invention is “sampling count ≧ recording data score”, and data memory is particularly compared with high sampling point recording. The number of recording data points stored in 4 can be greatly reduced.

  In the extreme point recording of the present invention, the time information between extreme points that are not temporally fixed is compensated by simultaneously recording the number of samplings between extreme points.

  By using such extreme point recording, it is possible to reliably record a minute change portion of the waveform that could not be recorded unless high sample point recording was performed, and to reduce the number of waveform data points to be recorded. The amount of data to be stored can be greatly reduced.

  FIG. 4 is a diagram for explaining the operation in the case of sampling and recording a sine wave of one cycle T = 1 second with a sample clock of 10 kS / s, and FIG. 5 is an example of sample data of FIG.

  When measured with the conventional apparatus shown in FIG. 6, digital data of 10,000 points per second is converted by the A / D converter 2 and stored in the data memory 4 as described above.

  On the other hand, according to the extreme point recording of the present invention, the data stored in the data memory 4 per second is the waveform data value and the extreme positive / negative extreme point data in one cycle of the sine wave unless the waveform is abnormal. There are only two points paired with the number of samplings between value points, and even if there is an abnormality in the waveform, the number of waveform data values and the number of samplings between extreme points in the abnormal waveform section are stored as a pair. Thus, the recording capacity is greatly reduced.

  By storing the waveform data values of extreme points and the number of samplings between extreme points in the data memory 4 as a pair, if the sine wave is correct, the transition of the number of samplings is constant, but the waveform variation is different from the others. When an abnormal waveform occurs, the number of samplings changes irregularly and does not become constant, so that the abnormal waveform can be easily detected from the data list as shown in FIG.

  Further, when the waveform is reproduced and displayed using the extreme point recorded data stored in the data memory 4, if the waveform is a triangular wave, the shape of the input waveform can be substantially reproduced by connecting the recorded extreme points as they are. . In the case of a sine wave, if the recorded extreme points are connected and displayed as they are, a triangular wave is obtained. However, an interpolation process such as spline interpolation can be applied to reproduce and display a shape that approximates the input waveform.

  As described above, according to the present invention, there is provided a data recording apparatus that can suppress the amount of recorded data while reliably recording minute fluctuations in the waveform, and can easily detect abnormal fluctuation portions of the waveform after recording. realizable.

DESCRIPTION OF SYMBOLS 1 Input part 2 A / D converter 3 Clock generator 4 Data memory 5 Waveform display part 6 Extreme point detection part 61 Differential operation part 62 Zero cross point detection part

Claims (4)

In a data recording apparatus configured to convert an analog input signal into digital data by an A / D converter and store the digital data in a data memory,
An extreme point detection unit for detecting an extreme point of an analog input signal based on digital data converted and output from the A / D converter is provided between the A / D converter and the data memory,
A data recording apparatus characterized in that the data memory stores extreme point data in which the detected waveform data value of each extreme point and the number of samplings between extreme points are paired.   The extreme point detection unit includes a differential calculation unit that calculates a slope of the analog input signal based on digital data converted and output from the A / D converter, and a sign of the slope of the analog input signal calculated by the differential calculation unit. The data recording apparatus according to claim 1, further comprising a zero cross point detection unit that detects a position at which the rotation is reversed.   The data recording apparatus according to claim 1, wherein a smoothing processing unit that removes a noise component of the analog input signal is provided in a front stage or a rear stage of the A / D converter.   The data recording apparatus according to claim 3, wherein the smoothing processing unit is a low-pass filter.

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