JPH02233005A - Real waveform simulation device - Google Patents

Abstract

PURPOSE:To obtain a consecutive repetitive simulation waveform by converting a waveform data stored in a memory into a waveform data having a period nearly equal to a measured period according to resampling and using a D/A converter so as to convert the data into an analog signal. CONSTITUTION:A waveform data Sd relating to a measured signal Sx is stored in a memory 4 via an A/D converter 2 and digital filter processing of a computing element 9 is used to apply resampling of the waveform data Sd stored in the memory 4. The data obtained in this way is fed to a D/A converter 5 to obtain a simulation waveform Ss of the waveform data Sd. Thus, the frequency of the measured signal Sx and the frequency of the simulation waveform Ss are made coincident in the calculation accuracy of the resampling and the repetitive simulation waveform Ss whose joint is consecutive is obtained.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention relates to an actual waveform simulation device that reproduces and outputs periodic measured waveforms, and more specifically, to a method for simulating discontinuities in the joints of repetitive output waveforms. It is about improvement. <Prior art> A type of waveform generator uses an A/D converter to convert a measured waveform into a digital signal, stores it in a memory, and adds the waveform data stored in the memory to the D/A converter for repeated processing. There is a real waveform simulation device that is configured to output as a waveform signal. FIG. 5 is a block diagram showing an example of such a conventional real waveform simulation device. In the figure, a measurement signal Sχ is applied to an A/D converter 2 via an input terminal 1 and converted into a digital signal sd. This digital signal sd is stored in the memory 4 according to the address applied from the address generator 3. The digital signal sd stored in the memory 4 in this way is repeatedly sent to the A/D according to the address added from the address generator 3.
The signal is read out by the converter 5 and outputted to the output terminal 6 as the actual waveform simulation signal Ss of the measurement signal Sχ. Note that these A/D converters 2. Address generator 3, memory 4
A clock pulse having a fixed frequency is applied to each of the D/A converters 5 and 5 from a clock generator 7. Problems to be Solved by the Invention In such a device, however, since the period of the measurement signal Sχ and the sampling period of the A/D converter 2 are generally asynchronous, The connection between the leading data and the trailing data of the waveform data Sd of the measurement signal Sχ stored in the memory 4 is often discontinuous. As a result, there is a problem in that the connection and repetition period of the simulation waveform Ss that is repeatedly reproduced and output via the D/A converter 5 becomes different from that of the measurement signal Sχ. The purpose of the present invention is to provide an actual waveform simulation device that can obtain continuous but continuous repeated simulation waveforms with a period approximately equal to that of the measured signal even when there are restrictions on the sampling period. There is a particular thing. Means for Solving the Problems〉 The actual waveform simulation device of the first invention includes: an A/D converter that converts a measured waveform into a digital signal; a memory that stores output data of the A/D converter; A computing unit that resamples the output data of the A/D converter stored in this memory to reproduce the period of the measured waveform, and converts the data resampled by this computing unit into an analog signal. A D/A converter that performs the following functions. A real waveform simulation device according to a second aspect of the invention includes: an A/D converter that converts a measured waveform into a digital signal; a memory that stores output data of the A/D converter; and the A/D converter that stores the output data of the A/D converter. A computing unit that performs spline interpolation to reproduce the period of the measured waveform on the output data of the D converter, and a D/A converter that converts the spline interpolated data by this computing unit into an analog signal. It is characterized by being structured. According to the actual waveform simulation device of the first invention, A
The waveform data stored in the memory via the /D converter is
The waveform data is converted into waveform data with a period approximately equal to the period of the measurement signal according to the digital filter-like calculation process of the arithmetic unit and resampling. By converting such waveform data into an analog signal using a D/A converter, a repetitive simulation waveform having a period approximately equal to that of the measurement signal can be obtained. Further, according to the actual waveform simulation device of the second invention, the waveform data stored in the memory via the A/D converter has a period approximately equal to the period of the measurement signal due to spline interpolation processing of the arithmetic unit. Converted to waveform data.

By converting such waveform data into an analog signal using a D/A converter, it is possible to obtain a repetitive simulation waveform having approximately the same period as the measurement signal, similarly to the first invention. Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration explanatory diagram showing an embodiment of the first invention, and the same parts as in FIG. 5 are given the same reference numerals. In the figure, a clock generator 8 is constructed so that its output frequency can be changed arbitrarily. Arithmetic unit 9 is A/D converter 2
The waveform data Sd stored in the memory 4 is subjected to digital filter-like arithmetic processing and resampling to convert it into waveform data having a period approximately equal to the period of the measurement signal Sχ. The operation of the device constructed in this way will be explained. First, A
Waveform data Sd related to the measurement signal Sχ is stored in the memory 4 via the /D converter 2. Here, if the measurement signal Sχ is a periodic signal, the number of data and the sample clock frequency of the A/D converter 2 are set so that waveform data sd of one cycle or more can be captured. Next, using the digital filter-like processing of the arithmetic unit 9,
The waveform data sd stored in the memory 4 is resampled. Here, the resampling period is approximately (waveform period/number of data in one period stored in the memory 4). Let's explain resampling. Denote the measurement signal Sχ by x(t). Here, t is time, and x(t) does not include components with a frequency of 1/τ or higher. If the sample points when N samples are sampled every period τ from t=0 are x1, then XTL=X(n・τ1) (n=0 to N-1). Also, if the period to be resampled is τ2, the resampling point is 37t, and the number of data after resampling is M, then x@=x(m-τ1》 (m=0 to M-1》). The condition for making the data after sampling match the data before resampling (x (t) = y (t)) is y1LL = ΣXTL sinc ( yr (τ2 /f
+)II-yc-n), and 《τ2/τ1》=1
If we set +α, it becomes. However, x(++jJ is 《1
+α》・If m is not an integer, it becomes zero. By performing such a series of arithmetic processing in the arithmetic unit 9, a new sample point yt can be obtained from the sample point x1 for each τ1, and the period of the measurement signal Sχ can be reproduced within the range of calculation accuracy. Figure 2 shows concrete examples of these.
a) shows the sample waveform by A/D converter 2, and (b)
) shows the waveform obtained by resampling (a) at four times the frequency. The data obtained by such resampling is added to the D/A converter 5 to obtain the simulation waveform Ss of the measurement signal Sχ.
obtain. At this time, the clock frequency of the D/A converter 5 is made to match the sample clock frequency of resampling. As a result, the frequency of the measurement signal Sχ and the frequency of the schulation waveform Ss can be matched within the range of calculation accuracy in resampling, and a continuous continuous schulation waveform Ss can be obtained. FIG. 2 is a configuration explanatory diagram showing an embodiment of the second invention, and the same parts as in FIG. 1 are given the same reference numerals. In the figure, a computing unit 10 performs spline interpolation processing on waveform data sd stored in a memory 4 via an A/D converter 2, and generates waveform data having a period approximately equal to the period of the measurement signal Sχ. Convert to . The operation shown in Fig. 3 will be explained using the waveform diagram shown in Fig. 4. First, a measurement signal S with a repetition period T1 as shown in (a)
χ is added to the A/D converter 2 and sampled using a sample clock with a period T2, and the sampling data shown in (b) is stored in the memory 4. In addition, ('rt /T2
) ~ is an integer. Next, the arithmetic unit 10 performs spline interpolation processing on the sampling data stored in the memory 4 to obtain continuous data that reproduces the measurement signal Sχ as shown by the broken line in (c). From this continuous data,
Reset the data (x mark) that is an integer fraction of the repetition period T1 at equal time intervals. After that, the retaken equally spaced data is added to the D/A converter 5, and the generation period of each equally spaced data is set as the period calculated in (c), and a connection signal equivalent to the measurement signal Sχ shown in (d) is generated. Reproduce and output the continuous repeated simulation waveform SS. According to the second invention, although the frequency components are somewhat less precise than the simulation waveform Ss obtained by the apparatus shown in FIG. It is more relaxed than the arithmetic unit 9 of the invention, and can be expected to have the effect of realizing high distance processing at a relatively low cost. In the embodiments shown in FIGS. 1 and 3, the A/D converter 2 and the D/A converter 4 are connected via the memory 4, and a common clock generator 8 generates respective clocks. Although we have shown an example of supplying data, for example, a digital oscilloscope is used as a data sampling block using an A/D converter, and the waveform data sampled by this digital oscilloscope is processed by the resampling processing function and D/A conversion as shown in Figure 1. It may be added to an arbitrary waveform generator having a waveform reproduction function using a device or a spline interpolation processing function as shown in FIG. 3 and a waveform reproduction function using a D/A converter. In addition, the digital data for resampling shown in Figure 1
The general formula for the filter characteristics is yIL=ΣXTL f(K(f2/ft)I1-π-n), and in the above example, f(t) is SinC(
Although we have explained the example of t), it is sufficient to use a function depending on the purpose. Furthermore, according to the present invention, the time axis of the actual waveform can be expanded or contracted without changing the sampling frequency. Effects of the Invention> As explained above, according to the present invention, an actual waveform simulation device is provided that can obtain a repeated simulation waveform with continuous connections having approximately the same period as the measurement signal even when there is a restriction on the sampling period. can be realized, and the practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the first invention;
3 is a block diagram showing an embodiment of the second invention, FIG. 4 is a waveform diagram explaining the operation of FIG. 3, and FIG. 5 is a diagram illustrating the operation of the conventional device. It is a block diagram showing an example. DESCRIPTION OF SYMBOLS 1... Input terminal, 2... A/D converter, 3... Address generator, 4... Memory, 5... D/A converter, 6... Output terminal, 8...・・Clock generator, 9・・
・Arithmetic unit (digital filter), 10...Arithmetic unit (
Spline Figure 3 Figure

Claims (2)

[Claims] (1) An A/D converter that converts the measured waveform into a digital signal, a memory that stores the output data of this A/D converter, and a memory that stores the output data of the A/D converter that is stored in this memory. and a D/A converter that converts the data resampled by the calculator into an analog signal. Real waveform simulation device. (2) An A/D converter that converts the measured waveform into a digital signal, a memory that stores the output data of this A/D converter, and a memory that stores the output data of the A/D converter that is stored in this memory. and a D/A converter that converts data spline interpolated by this calculator into an analog signal. Real waveform simulation device.