JPS59226875A - waveform storage device - Google Patents

Abstract

PURPOSE:To magnify and observe a high display resolution at an optional position of a waveform by sampling the waveform after a specified point by the second sampling clock at a higher speed. CONSTITUTION:From which point a magnified sampling is executed is designated in seeing a waveform displayed on a tube surface. As a result, a signal 21 is generated in the head part of the waveform displayed on the tube surface, and when this signal 21 is inputted, counting of the first sampling clock 11 is started by a counter 14, but a sampling operation is not executed. Subsequently, when a comparing and controlling circuit 17 detects a fact that a counting signal 23 has coincided with a position data 16', namely, when a designated magnified sampling start point is detected, sampling is started. This sampling is continued until the counting signal 23 of the counter 14 attains a prescribed value, and an obtained data is outputted to a display memory 7 and displayed. In such a way, a high display resolution can be magnified and observed at an optional position of a waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a waveform storage method for a device (hereinafter abbreviated as digital oscilloscope) that digitally stores and observes a human signal waveform, such as a digital storage oscilloscope.

(Prior art and its problems) In a digital oscilloscope, a human input signal waveform is sampled using a preset sampling clock, IZA/D converted, the resulting digital data is stored in a digital memory, and it can be stored at any time or at a desired time. A common method is to repeatedly read out the data, perform D/A conversion, and display it on a cathode ray tube or the like.

Conventionally, in digital oscilloscopes, the measures to enlarge and display the waveform are as follows: (1) When displaying data already stored in the memory, compared to when it is not enlarged, Increase surface sweep speed.

Or, (2) slow down the memory read speed without changing the screen sweep speed.
It has generally been the case that the data output speed is relatively low to provide an equivalent waveform enlargement display effect.

This method intentionally coarsens the display resolution of each sample data in the time axis direction, and can be said to be a suitable method when, for example, it is desired to see in detail the transition status of signal data for each sample.

However, it is not suitable for the purpose of observing in more detail the state of waveform transition within one sample clock period.

A simple example of a case where such a request occurs is the waveform shown in FIG. 1. This example is an example where the disturbance signal 2 is mixed in a part of the very long-period repetitive signal 1, and 1 hour T1゜T2 is very long, and 2 hours τ is very short compared to +r, , T2. do. signal 2
If you want to expand and observe only the period of τ in order to investigate the factors, etc.

In a normal digital oscilloscope, this is the rising edge of signal 1.

Or start sampling using the falling edge as the reference point,
The results are stored in memory, but in order to store the entire waveform as shown in Figure 1 in the specified memory capacity, the sampling clock period must be long, and in such a case, the above-mentioned Even with an enlargement method, it is not possible to observe the transition situation during the period of τ in detail.

On the other hand, sample with a sufficiently fast sampling clock,
If the result is stored in memory, it becomes possible to observe the transition of signal 2 using the aforementioned enlarged display method, but the number of sample data of signal 1 sampled using such a sampling clock becomes large.

A large memory capacity is required.

Although FIG. 1 is an example for explaining the shortcomings of the conventional method, many such examples are encountered by those who use this type of measuring instrument.

(Purpose) This invention counts samples up to an arbitrary specific point in a human-powered waveform using a first sample clock, specifies that specific point, and samples the waveform after that specific point using a faster second sample clock. Its purpose is to display a portion of a 9-periodic human-powered waveform from an arbitrary specific point onwards as an enlarged waveform with high display resolution.

(Example) An embodiment of the present invention will be described below with reference to FIG.

Reference numeral 3 denotes an A/D converter which converts the analog human input signal 4, which is a one-periodic human input waveform, every time using a prescribed sample clock 5, and A/D converts it. 6 is a sample data memory for storing output data from the A/D converter 3, and 7 is a display memory for storing display data. During display, this display memory 7 is synchronized with a sweep signal from a cathode ray tube, etc. Data is output, and the output data 8 is D/A converted by a subsequent D/A converter (not shown), and output to a cathode ray tube or the like to display a desired waveform.

On the other hand, 9 is a sample clock generation circuit which receives information from the digital oscilloscope panel switch.

Information signal 10 from a microcomputer, etc. that controls this
As a result, a first sample clock 11 corresponding to the designated sampling period and a second sample clock 12 faster than the specified sampling period are output. 13 is a selector for selectively outputting the first sample clock 11 and the second sample clock 12; 14 is a counter for counting the sample clock output from the selector 13; 15 is a counter for counting the position data 16 of a specific point in the aforementioned human waveform; This is a latch circuit for holding. 17 is a comparison control circuit.

Next, this operation will be explained. Below, the data sampling by the 10th sample clock 11 is a normal sample.
Data sampling by the second sample clock 12 will be referred to as expanded sampling.

The distinction between the normal sample mode and the enlarged sample mode is given to the comparison control circuit 17 as a sample mode signal 18 by the operator's operation of a panel switch. During normal sampling, the comparison control circuit 17 receives the reset signal 19
The trigger signal 2 from the trigger detection circuit (not shown) of a manual signal is set in the state where the counter 14 is set to the initial state by the trigger signal 20 and the selector 13 is made to select the first sample clock 11 by the sample clock switching control signal 20 at the same time.
Wait for 1. When the trigger signal 21 is input manually, the gate signal 22 is set to 1'', the sampling clock 11 is supplied from the sample clock generation circuit 9 to the A/D converter 3 and the memory 6 via the selector 13, and sampling starts. At the same time, the counter 14 counts the number of sample data. Count signal 23 which is the content of counter 14
When reaches a specified value (mainly determined by memory capacity), the comparison control circuit 17 sets the gate signal 22 to '0''',
The sampling operation is stopped, and one sampling of the specified number of times is completed. Since the sampling results are held in the sample data memory 6, by transferring these data to the display memory 7, the sampled data can be displayed as a waveform. Next, the operation in enlarged sample mode will be explained.

To perform an enlarged sample, sample with 2 normal samples, and while watching the waveform displayed on the screen, specify from which point you want to perform the enlarged sample. As this specifying method, many known methods can be applied, such as a method of moving a cursor to a desired position on the tube surface, a method of specifying a position on the tube surface using a digital switch, etc. The position specified in this way (high-speed sample starting point) information is provided as 2-position data 16.

By setting the latch 15 and the sample mode signal 18.

Specifies enlarged sample mode.

The comparison control circuit 17 outputs a reset signal 19 to set the counter 14 to an initial state, and at the same time outputs a sample clock switching control signal 20 to cause the selector 13 to select the first sample clock 11 and waits for a trigger signal 21. A signal 21 is generated at the beginning of the waveform displayed on the screen, and when this signal 21 is input manually, the counter 14 starts counting the first sample clock 11, but the gate signal 22 is +
Keep it at 101+ and do not perform sample operation. This state is maintained until the output count signal 23 of the counter 14 and the position data 16' of the high speed sampling start point of the latch 15 match.

When the position data 16' and the count signal 23 match, that point corresponds to the enlarged sample starting point designated by the operator. Comparison control circuit 17 receives count signal 239 position data 1
6', the reset signal 19 returns the counter 14 to its initial state, the sample clock switching control signal 20 causes the selector 13 to select the second sample clock 12, and the gate signal 22 is switched to
The sample clock 5 is output to the A/D converter 3 and the sample data memory 6 to start sampling. This sampling is continued until the count signal 23 of the counter 14 reaches a specified value in the same way as one normal sample. The data obtained as this sample is displayed in the memory 7.
The operation of outputting and displaying is the same as for normal samples. Therefore, the waveform 20 portion in FIG. 1 is enlarged and displayed with high accuracy on the display screen.

With the above operation, by enlarging and sampling a waveform that has been previously sampled and displayed in normal sample mode from any position using a faster sample clock, it becomes possible to enlarge and observe the waveform at any position with high display resolution. .

(Effects) As explained above, according to the present invention, it is possible to realize the function of performing sampling from any position of a repetitive signal using a high-speed clock, and to perform sampling at any arbitrary position of a repetitive signal without increasing the capacity of digital memory. A digital oscilloscope that can display an enlarged waveform with high display resolution from the position can be realized at a very low cost.

[Brief explanation of drawings]

FIG. 1 is a waveform diagram of a conventional method, and FIG. 2 is a block diagram of an embodiment of the present invention. 3: A/D converter, 6: Sample data memory. 7: Display memory, 9: Sample clock generation circuit. 13: Selector, 14: Counter, 15: Lanochi, 17
: Comparison control circuit.

Claims (1)

[Claims] In a digital waveform storage device, a point is detected from a trigger detection point or a sample start point of a two-person input signal to a specified arbitrary point by counting the first clock; Subsequent human input signals are sampled using a second clock faster than the first clock. A waveform storage device characterized by storing data.