JPH0611477Y2 - High-speed Fourier transform analyzer - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is a waveform analysis device using a fast Fourier transform (often called FFT after taking the initials of three words forming an English term). Regarding the improvement of the FFT analyzer.

[Conventional technology]

In recent years, a digital signal processing technique has been adopted to improve the performance of a waveform analysis device, and the technical idea disclosed in Japanese Patent Laid-Open No. 52-131768 is regarded as a typical one.

According to this disclosure, the information of the wave in the time domain displayed on the display screen in the range set by the cursor is obtained, and the four arithmetic operations of digital are applied to it, and the information of the wave in the range set by the two cursors is obtained. It is shown to get the maximum and minimum of the wave.

On the other hand, especially in signal transmission in the communication field and in identifying the properties of substances in nondestructive testing, it is necessary to analyze the frequency components of signals.
The present invention is intended for application in this field.

A known FFT analyzer is, for example, the applicant's FFT digital scope MS210A manufactured by Anritsu Corporation.
(See CAT.NO.MS210A-1, catalog issued in May 1985). These FFT analyzers sample and store the data to be measured (analog waveform information) in a waveform storage memory (wave memory) and display the waveform on a CRT display device, or at high speed from the time domain to the frequency domain. The information obtained by the Fourier transform (FFT) is displayed on a CRT display device alone or side by side with the original time domain waveform.

In the conventional technique, it is common knowledge that only the data necessary for FFT analysis is stored in the wave memory, and all the stored data is subjected to FFT analysis, which has been standardized. Therefore, the time domain waveform displayed on the CRT display is naturally only the range to be analyzed,
That was all.

This means that when a large-capacity wave memory appears in recent years and is easily available, the FFT analyzer used for storing a large amount of waveform data by using the large-capacity wave memory. The function is extremely inconvenient. For example, there is a case in which it is desired to perform FFT analysis only on a part having a characteristic in the waveform stored in the wave memory. In this case, there is an example in which a certain range is limited, the stored information is drawn from the wave memory, the FFT analysis is performed on the limited range, and the function is displayed. (Refer to the catalog issued by Yokogawa Hewlett-Packard Co., Ltd. Dynamic Signal Analyzer Model3561A: TECNICAL DATA JUN.'84) However, in this case, the function of displaying the entire contents of the wave memory must be sacrificed.

[Problems to be solved by the device]

In the prior art, some FFT analyzers have a function of expanding or compressing a waveform in the time domain and a function of resetting a frequency analysis position (center frequency) in the frequency domain. However, while observing a large amount of waveform data stored in a large-capacity wave memory, that is, time domain information on the CRT display, the operator arbitrarily sets the range to be analyzed and
There has been nothing that can perform FFT analysis to obtain spectrum, that is, frequency domain information, and display the both domain information in association with each other.

When performing FFT analysis on transient or transient phenomena, apart from when performing FFT analysis on stationary waveforms (eg, repeated sine waves with constant frequency), specify the range to be analyzed. It must be meaningfully specified, and the machine cannot automatically make all this meaningful specification, and thus requires some form of operator involvement. The present invention aims to provide the FFT analyzer with a function that facilitates access to humans or machines.

[Means for Solving the Problems]

In this invention, in the fast Fourier transform analyzer,
On the screen that displays the information stored in the wave memory,
As a display that specifies the range for FFT analysis, the cursor appears so that it can appear, and the operator can arbitrarily specify the start point and end point of the cursor, or one of them, while observing the display screen. ing. Also,
The FFT operation is executed for the specified range and the result can be displayed.

[Action]

Therefore, for example, while observing the entire 256-kilo point data stored in the wave memory on the CRT display device, the cursor (preferably two vertical lines) indicating the range to be subjected to FFT analysis is displayed on the display. The FFT analysis can be performed by superimposing on, and quickly selecting and determining the range of time extraction on the time domain waveform. Therefore, the FFT analysis does not need to be performed on the 256 kilo point data, and the calculation can be performed quickly.

〔Example〕

FIG. 1 is a diagram showing the configuration of a first embodiment of an FFT analyzer according to the present invention. The observation data is introduced from the input terminal 1 and is a wave memory (WM) 2 which is a waveform information storage device.
Memorized in. This stored information is added to the means (FFT) 3 for executing the FFT operation, and is added to the CRT display device 6 via the switch 4 and the display control means (DISP CON) 5. The information stored in the wave memory 2 is
Some routes are displayed on the CRT without going through the FFT. The switch (SW) 4 is a means for switching between displaying information passing through the FFT and information not displaying it, and displaying both of them. The operator 10 looks at the time domain waveform (the horizontal axis is the time axis) as shown in FIG. 2 displayed on the display screen of the CRT and determines the range for FFT analysis. This decision is FF by knob 7
Tell the T analyzer. This human operation can be done while looking at the CRT display. On the display device, two vertical cursors are displayed so as to overlap with the time domain waveform in order to display the range designated by the operator's decision. This function is provided, for example, in the control means 5 of the display device with cursor generating means CURSOR which erases the amplitude value (vertical axis value) held by the information from WM2 and makes the vertical axis lie in place of it. Alternatively, a special code may be introduced into the address information of WM2. For this range specification information, only the start point of the range may be given, and the range after which FFT analysis is performed may be specified separately (or determined by the performance of the device itself). Conversely, only the end point may be specified. Good. FFT in the range thus specified
Analysis is performed to obtain a frequency domain waveform (spectrum) as shown in FIG. It is preferable that the waveforms of both FIG. 2 and FIG. 3 are displayed side by side on the screen of the CRT display device.

FIG. 4 is a diagram showing the configuration of the second embodiment of the FFT analyzer according to the present invention. In this example, the information stored in the WM 2 is added to the means (FFT) 3 for executing the FFT calculation via the trimming means 9. When viewed on a CRT display, it is as shown in FIG. 5, and the information stored in the WM initially shows a wide range as shown in FIG. 5 (a), but the operator (not shown) The decision is to specify the range of the starting point 13 and the ending point 14, and the specified information is F through the knobs 7a and 7b.
It is assumed that the data is input to the FT analyzer. As a result, the trimming means limits the data extraction from WM2, displays only the range as shown in (b) on the CRT, and only the range indicated by the markers 13 and 14 is the target of the FFT calculation. Other operations are the same as those in the first embodiment (FIG. 1).

In addition, for the sake of simplicity, in the above-mentioned embodiment, the FFT operation is performed on the information (waveform) in the time domain to obtain the information (spectrum) in the frequency domain, and the device for displaying it or the information is displayed. It is well known that the information is a spectrum and an inverse FFT operation is performed on the spectrum to obtain a spectrum, which is a substantially similar operation (complementarity of time and frequency). It goes without saying that FFT (calculation operation is the same) is the same technology.

[Effect of device]

In this invention, the range designation information setting means is prepared as a means for the operator to easily specify the range to be subjected to the FFT operation among the data stored in the wave memory. It is quickly transmitted to the FFT analyzer, and there is no need to perform FFT calculation on wasteful information,
In addition, since the calculation can be executed at high speed, it greatly contributes to the waveform analysis technology.

For example, from the signals that include impulse-shaped signals and reflected signals derived from them, only impulse signals are extracted while observing the waveform, and Fourier-transformed waveform analysis is performed. It is possible to perform waveform analysis by performing Fourier transform by extracting only the reflected signal.

Alternatively, burst signals used in digital mobile communication can be cut out and extracted while being analyzed and used for waveform analysis.

Therefore, a fast Fourier transform technology suitable for use in fields requiring analysis of individual delicate frequency spectra, such as signal analysis in acoustic emission (AE) and analysis of crosstalk (crosstalk) characteristics in communication lines. Could be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention, FIGS. 2 and 3 are schematic diagrams of waveforms displayed by the device of the present invention,
FIG. 4 is a diagram showing the configuration of the second embodiment of the present invention, and FIGS. 5 (a) and 5 (b) are schematic diagrams of waveforms displayed by the device of the second embodiment of the present invention. The numbers in the figure are 2: wave memory 3: FFT calculation execution means 5: display control means 6: display means 7: range designation information input means.

Claims (1)

[Scope of utility model registration request] 1. A fast Fourier transform analyzer having a function of performing FFT analysis on waveform information in the time domain stored in a wave memory, converting the waveform information into frequency domain waveform information, and displaying one or both of the waveform information. Of the waveform information in the time domain displayed on the display screen, FF
T: Input means (7) for setting range designation information for designating at least one of a start point and an end point of a range to be analyzed, and a time stored in the wave memory of the range set by the input means. One of FFT calculation executing means (3) for performing FFT analysis based on the waveform information in the area and outputting the waveform information in the frequency domain, and the range set by the input means and the waveform information output by the FFT calculation executing means, or A fast Fourier transform analyzer comprising display control means (5) for visually displaying both of them on a display screen.