JPH01311282A - Waveform display device - Google Patents

Abstract

PURPOSE:To process data in a relatively short time by providing a trigger generating circuit, a phase turbulance signal generator, a sampling pulse generator, a digitizing circuit, a timer interval measuring instrument, a time matching circuit, etc. CONSTITUTION:The trigger generating circuit 3 outputs a trigger pulse selectively at a trigger point where a repetitive analog input signal crosses a trigger level. The sampling pulse generator 4 is applied with the output signal of the phase turbulence signal generator 5 through a switch 6 and outputs a sampling pulse train of specific frequency. The digitizing circuit 2 converts the analog input signal into digital waveform data according to the sampling pulses. The time interval measuring instrument 7 measures the time interval from the trigger point and a 1st sampling pulse following the trigger point. A memory 9 is stored with the digital waveform data outputted by the circuit 2 and the measurement result of the measuring instrument 7. The time matching circuit 10 matches the measurement results of the measuring instrument 7 and memory 9 with each other to detect the same measurement result and updates digital waveform data regarding the time result stored in the memory 9 selectively.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a waveform display device,
More specifically, the present invention relates to improvement of waveform display using equivalent time sampling.

(Prior art) A type of waveform display device digitizes an analog input signal by equivalent time sampling and stores it in a waveform memory.
Some devices are configured to reproduce and display analog input signals based on waveform data stored in this waveform memory.

Here, equivalent time sampling is a method of reproducing an input waveform by sampling one part from each repetition of a repetitive signal waveform, and sequential sampling is a method in which the phase of the sample clock is varied by a fixed amount of time for each repetition. There is random sampling in which the phase of the sample clock for each repetition is randomly aligned to an arbitrary time range.

According to such equivalent time sampling, the input signal must be a stable repeating signal in order to reproduce one complete waveform, but even an input signal with a frequency higher than the sample clock frequency can be sampled. can do.

By the way, conventional random sampling is configured to perform sampling once for each repetition, as shown in FIG.

FIG. 8 is an explanatory diagram of waveform reconstruction based on data sampled in this manner. Let the repetition period be T,
When the number of data points is N, the time slot width of each data position is T/N. Here, the probability P that N pieces of data are collected in all time slots by performing random sampling m times is as follows.

(Problem to be solved by the invention) However, according to such a conventional configuration, in order to reconstruct the waveform, it is necessary to perform multiple samplings and the time from the trigger point to the sampling link for each sampling. There is a problem that it takes a long time to process the data, which requires concubinage.

The present invention has focused on these points, and its purpose is to provide a waveform display device using a random sampling method that can process data in a relatively short time.

(Means for Solving the Problems) A waveform display device of the present invention includes: a trigger generation circuit that selectively outputs a trigger pulse at a trigger point where a repetitive analog input signal crosses a trigger level; a phase disturbance signal generator; A sampling pulse generator to which the output signal of the phase disturbance signal generator is applied via a switch and outputs a sampling pulse train of a predetermined frequency, a digitization circuit that converts an analog input signal into digital waveform data according to the sampling pulse, and a trigger. a time interval measuring device for measuring a time interval between a point and a first sampling pulse following a trigger point; a memory for storing digital waveform data output from a digitizing circuit and measurement results of the time interval measuring device; and a time interval measuring device. The measurement results of the time interval measurement device are compared with the measurement results of the time interval measurement device stored in the memory, and when the same measurement results are detected, the switch is selectively driven and the corresponding time measurement results stored in the memory are detected. and a display data generation circuit that generates waveform display data according to the time measurement results and digital waveform data stored in the memory. Features.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an amplifier that amplifies an analog human input signal, and its output signal is applied to a digitization circuit 2 and a trigger generation circuit 3. The output signal of the trigger generation circuit 3 is applied to a time interval measuring device 7 and also to an address generator 8. 4 is a sampling pulse generator that outputs a sampling pulse train of a predetermined frequency. A phase disturbance signal generator 5 disturbs the phase of the output signal of the sampling pulse generator 4, and is connected to the sampling pulse generator 4 via a switch 6. Such a phase disturbance signal generator 5
For example, a random noise generator is used as the sampling pulse generator 4, and a crystal oscillator as shown in FIG. 2 is used as the sampling pulse generator 4, for example. The output signal of the sampling pulse generator 4 is applied to a digitizing circuit 21, a time interval measuring device 7 and an address generator 8. Digitization circuit 2
converts the analog input signal into a digital signal according to the sampling pulse, and outputs it to the memory 9.The time interval measuring device 7 measures the time interval between the trigger pulse output from the trigger generation circuit 3 and the sampling pulse following this trigger pulse. and is added to the memory 9 and time matching circuit 10. Address generator 8 outputs address data updated according to the sampling pulse to memory 9.

In accordance with the address data output from the address generator 8, the memory 9 stores the time interval measurement results in each trigger period and a sampling waveform data sequence based on the sampling pulse sequence of the trigger pulse. The time matching circuit 10 successively matches the measurement results of the time interval measuring device 7 and the measurement results of the time interval measuring device 7 stored in the memory 9 to detect identical measurement results. By detecting the same measurement result, the switch 6 is selectively driven to disturb the output signal phase of the sampling pulse generator 4, and the digital waveform related to the corresponding time measurement result stored in the memory 9 is generated. Controls address generator 8 to selectively update data. Reference numeral 11 denotes a display data generation circuit that generates display data based on the time interval measurement results and sampling waveform data stored in the memory 9.

A trigger control circuit 12 controls the trigger pulse generation operation of the trigger generation circuit 3 in accordance with a control signal applied from the address generator 8.

The operation of the apparatus configured in this way will be explained using FIG. 3.

When the power is turned on, the switch 6 is off, and the sampling pulse generator 4 outputs a sampling pulse train with a period 'rs. The trigger control circuit 12 first outputs an output command signal to the trigger generation circuit 3 immediately after power is turned on, and thereafter selectively outputs an output command signal in accordance with a control signal applied from the address generator 8. The trigger generation circuit 3 outputs a trigger pulse to the time interval measuring device 7 and the address generator 8 at the time when the analog input signal first crosses the trigger level after the output command signal is applied from the trigger control circuit 12; Trigger control circuit 12
The time interval measuring device 7, which waits for the output of the trigger pulse until the output of the trigger pulse is instructed, measures the time interval T between the trigger pulse output from the trigger generation circuit 3 and the sampling pulse following this trigger pulse. and is added to the memory 9 and time matching circuit 10. The digitizing circuit 2 samples the analog input signal according to the sampling pulse train applied from the sampling pulse generator 4, converts it into a digital signal, and outputs it to the memory 9 as a first digital waveform data train. The measurement data of the time interval measuring device 7 and the first waveform data string output from the digitizing circuit 2 are stored in the memory 9 according to the address data output from the address generator 8.

The address generator 8 is preset with the number of data constituting each digital waveform data string calculated according to the waveform display setting conditions and the total number of digital waveform data strings to be stored, and is counted down according to the sampling pulse. Manage the number of data imports by doing this. Here, the length of the time axis on the display is '1'. , the number of display dots is i, and the period of the sampling pulse is Ts, then the number m of digital waveform data strings is m='l''s−i/Tq.Then, the number of data forming each digital waveform data string is N becomes N='r''o/Ts.

That is, when the first trigger pulse is output after the power is turned on, the address generator 8 generates the first trigger pulse, which consists of time interval measurement data up to the first sampling pulse following the trigger pulse, and N digital waveform data following the trigger pulse. The head address data for storing one digital waveform data string is output to the memory 9. When a sampling pulse of Ntm is applied, a control signal is outputted to the trigger control circuit 12 to control the trigger generation circuit 3 to generate a second trigger pulse. Trigger control circuit 12 receives this control signal and outputs a second trigger pulse output command signal to trigger generation circuit 3. As a result, the trigger generation circuit 3 outputs the second trigger pulse to the time interval measuring device 7 and the address generator 8, and thereafter continues to pulse again until the trigger pulse output is instructed by the trigger control circuit 12. The two-time interval measuring device 7, which waits for the output of Add to 10. The digitizing circuit 2 samples the analog input signal according to the sampling pulse train applied from the sampling pulse generator 4, converts it into a digital signal, and outputs it to the memory 9 as a second digital waveform data train.

The measurement data of the time interval measuring device 7 and the waveform data string output from the digitizing circuit 2 are transferred to an address generator 8.
The data is stored in the memory 9 according to the address data output from the address data.

That is, when the second trigger pulse is output after the power is turned on, the address generator 8 generates time interval measurement data up to the first sampling pulse following the trigger pulse and N digital waveform data following the I-reca pulse. The head address data in which the second digital waveform data string consisting of the following data is to be stored is output to the memory 9.

Thereafter, such a series of operations is repeated until the total number of digital waveform data strings stored in the memory 9 or the number set in advance in the address generator 8 is reached.

The time matching circuit 10 sequentially matches the measurement results of the time interval measuring device 7 with the measurement results of the time interval measuring device 7 stored in the memory 9 in the process of storing such a series of data. When the same measurement result is detected, the switch 6 is selectively driven to disturb the phase of the sampling pulse output from the sampling pulse generator 4, and the corresponding time 8 stored in the memory 9 is generated. control to selectively update digital waveform data related to the specified results. This prevents the same point from being sampled each time the relationship between the repetition frequency of the analog input signal and the repetition frequency of the sampling pulse is an integral multiple or a fraction of an integral number. For example, assume that the time interval measurement result of the fifth column of digital waveform data matches the time interval measurement result of the second column of digital waveform data stored in the memory 9. In this case, the current measurement data is stored as data in the fifth column, and the measurement data in the second column is updated with the next measurement data.

Such a procedure is repeated to store the necessary number of digital waveform data strings in the memory 9.

The display data generation circuit 11 generates waveform display data as shown in FIG. 4 according to the time measurement results and digital waveform data stored in the memory 9 in this manner. In FIG. 4, the circle mark indicates the digital waveform data string obtained by the 14th sampling, and the X mark indicates the digital waveform data string obtained by the 24th sampling. Here, if the repetition period] is set to '=K・'rs and the number of data points is N, the time slot width of each data position is 'I'/N. Then, sampling is performed randomly m times. All you have to do is tie.

In other words, with this configuration, the probability that N pieces of data are available in all time slots is 1 compared to the conventional method.
The number of time data stored can be reduced, and waveform reconstruction processing can be performed relatively easily.
Quick waveform display can be achieved.

Note that a crystal oscillator may be used as the phase disturbance signal generator 5, as shown in FIG. 5, for example.

In this case, the frequencies of the output signals of the sampling pulse generator 4 and the phase disturbance signal generator 5 are uncorrelated with each other, and either the fundamental frequencies f and f2 of the output signals of both are approximately equal, or the fundamental frequency of one of them is Make the other odd harmonics approximately equal. If f2 and f2 are set to be approximately equal at the fundamental frequency of both output signals, a switch 13 that is driven to open and close complementary to the switch 6 is provided as shown by the broken line, and the sampling pulse train is output from the sampling pulse generator 4. When outputting a signal, the switch 6 is closed and the signal is once drawn into the output signal of the phase disturbance signal generator 5, and then the switch 6 is opened to cause self-excitation. When the sampling pulse generator 4 is self-excited, the switch 13 is output. is closed to draw the phase disturbance signal generator 5 into the output signal of the sampling pulse generator 4. As a result, the phase of the sampling pulse can be substantially disturbed, and a phase disturbance signal having a relatively high amplitude level can be obtained compared to a configuration using a random noise generator, so that the circuit can be simplified. Note that the switch 13 is not required when the fundamental frequency on one side and the odd harmonics on the other side are made approximately equal.

Further, according to the present invention, by applying a pre-trigger, it is also possible to display and observe the waveform before the trigger point.

FIG. 6 is a block diagram showing an example of a repaired device capable of such pre-trigger measurement. In FIG. 0, the same parts as in FIG. , the number of digital waveform data to be captured by the address generator 8 before reaching the trigger point is set in advance. In such a configuration, for example, if each digital waveform data string is composed of 100 pieces of data, and 50 pieces of data are taken in before reaching the trigger point, the address generator 8 stores these values. Set in advance. The address generator 8 outputs a control signal to the trigger control circuit 12 when 50 pieces of data are taken into the memory 9 as the first column data, and the trigger control circuit 12 outputs a trigger pulse to the trigger generation circuit 3. Output a command signal. Until the trigger pulse is output, the numbers 1 to 100 assigned to the first column of the memory 9 are
In the data area for 0 pieces, data is sequentially updated and stored in a ring shape. For example, if the trigger pulse is output after the 55th data is stored as shown in the first sample sequence in Figure 7, then the 50 data following the 56th will be the data after the trigger point, and for example, the second sample sequence in Figure 7. As shown in the sample string, if the data is output after the 11th data is stored, the 50 data following the 12th will be the data after the trigger point. In the former case, the 50 data from No. 56 to No. 5 through No. 100 become data after the trigger point, and the data between No. 50 and No. 6 to No. 55 become data before the trigger point (pre-trigger area). In the latter case, the 50 data from No. 12 to 61, or the data after the trigger point, and the 50 data from No. 62 through No. 100 to No. 11, or the data before the trigger point (pre-trigger area). It becomes data. The memory 9 is provided with a pointer to indicate the position of the data at which the trigger pulse is output for each data string, and also stores time measurement data up to the first sampling pulse following the trigger point. Note that when the time measurement data match, disturbance is given to the phase of the sampling pulse as in FIG. 1. By repeating these steps, the required number of digital waveform data strings are stored in the memory 9.
The display data generation circuit 11 generates waveform display data as shown in FIG. 8 in accordance with the time measurement results and digital waveform data stored in the memory 9 in this manner. In FIG. 8, the ◯ marks indicate the digital waveform data strings obtained by the first sampling, and the X marks indicate the digital waveform data strings obtained by the second sampling.

With this configuration, the waveform before the trigger point can also be displayed and observed.

By the way, in the configuration shown in FIG. 6, the frequency of the analog input signal is equal to the frequency f of the sampling pulse as shown in FIG.
If the value is higher than , it will not be possible to capture random data concentrated in a specific area such as the trigger pulse generation position, and when the waveform is reconstructed, the continuity of the displayed waveform will be lost as shown in Figure 10. This causes the inconvenience of being damaged. In FIG. 9, (a) shows a trigger output command signal, (b) shows a sampling pulse train, and (C) shows an analog input signal. Here, the sampling pulse frequency f
+ (=1/'I゛s) is approximately 1/2 of the analog input signal. As a result, the position where the trigger pulse is generated is limited to the first repeated waveform A following the sampling pulse, and the trigger pulse is not output at the second repeated waveform B. Based on such sampling data, When the waveform is reconstructed, part A is displayed as shown in FIG. 10, but part B cannot be displayed because sampling data is missing.

Such inconveniences can be solved by randomly generating trigger output control signals. FIG. 11 is a block diagram showing an embodiment of such a device, and FIG. 12 shows the trigger generation circuit 3 and trigger control circuit 12 in FIG.
It is a block diagram showing a specific example. In Figure 12,
The respective output frequencies ft and fz of the sampling pulse generator 4 and the phase disturbance generator 5 have the same relationship as shown in FIG. 1
5 to 18 are flip-flops. The output signal of the phase disturbance signal generator 5 is applied to the tallock terminal of the flip-flop 15, and the data terminal and the inverting output terminal are connected in common to the tallock terminals of the flip-flops 16 and 17. From this flip-flop 15,
An output signal with a frequency of (f2/2) < f+ is output. A trigger pulse output control signal is applied from the address generator 8 to the data terminal of the flip-flop 16, and its non-inverting output terminal is connected to the data terminal of the flip-flop 17. As a result, the phase of the output control signal of the trigger pulse is disturbed with respect to the sampling pulse. A non-inverting output terminal of flip-flop 17 is connected to a data terminal of flip-flop 18;
A trigger pulse is applied to the clock terminal of the flip-flop 18, and the trigger pulse is outputted from the non-inverting output terminal of the flip-flop 18 in a temporally random relationship with respect to the sampling pulse.

With this configuration, a stable waveform display operation can always be obtained regardless of the frequency of the analog input signal and the sampling pulse.

In addition, in FIG. 12, instead of dividing the output signal of the phase disturbance signal generator 5 by the flip-flop 15, a clock of frequency f3 (<f+ and uncorrelated with f) is output as shown by the broken line. A clock generator 19 may be provided and its output signal applied to the clock terminal of each flip-flop 16,17.

(Effects of the Invention) As described above, according to the present invention, it is possible to realize a waveform display device using a random sampling method that can process data in a relatively short time, and the practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific example of the main part of FIG. 1, and FIGS.
1 is an explanatory diagram of the operation of FIG. 1, FIG. 5 is a block diagram showing another specific example of the main part of FIG. 1, FIG. FIG. 10 is an explanatory diagram of the operation of FIG. 6, FIG. 1 is also a block diagram showing another embodiment of the present invention, and FIG. 12 is a block diagram showing a specific example of the main part of FIG. 11, and an explanatory diagram of the operation. , FIG. 13, and FIG. 14 are explanatory diagrams of the operation of the conventional device. 1... Input amplifier, 2... Digitization circuit, 3...
・Trigger generator, 4... sampling pulse generator,
5... Phase disturbance signal generator, 6... Switch, 7...
...Time interval measuring device, 8...Address generator, 9...
- Memory, 10... Time verification circuit, 11... Display data generation circuit, 12... Trigger control circuit. Agent: Patent Attorney Shinbo Ozawa,・1, Nishin2! ￥l ・3) Figure 5 611 H113 Figure 12

Claims (1)

[Scope of Claims] A trigger generation circuit that selectively outputs a trigger pulse at a trigger point where a repetitive analog input signal crosses a trigger level; a phase disturbance signal generator; and an output signal of the phase disturbance signal generator via a switch. A sampling pulse generator that outputs a sampling pulse train of a predetermined frequency; a digitization circuit that converts an analog input signal into digital waveform data according to the sampling pulse; a time interval measuring device that measures time intervals; a memory that stores digital waveform data output from the digitization circuit and the measurement results of the time interval measuring device; and a memory that stores the measurement results of the time interval measuring device and the time stored in the memory. The measurement results of the interval measuring device are sequentially compared, and when the same measurement result is detected, the switch is selectively driven, and the digital waveform data related to the corresponding time measurement result stored in the memory is selectively updated. What is claimed is: 1. A waveform display device comprising: a time verification circuit that controls the time to perform control, and a display data generation circuit that generates waveform display data according to time measurement results and digital waveform data stored in a memory.