JP2003098193A - Waveform display device - Google Patents

Abstract

(57) [Problem] To provide a waveform display device capable of observing a waveform when a stable trigger cannot be obtained or a random noise and a sudden noise are removed from a waveform in which a sudden noise occurs. SOLUTION: History memory means for retaining past waveform data for a designated number of times of trigger in an acquisition memory, extraction means for extracting waveform data of the retained data at the same time, and storing an arbitrary value of the extracted waveform data. And a waveform display means for selecting and displaying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform display device, and more particularly to a display device that attenuates and displays a noise component.

[0002]

2. Description of the Related Art FIG. 4 is a functional block diagram showing a configuration of a general digital oscilloscope. The analog input signal Ei is amplified (including attenuated) by the input amplifier 1,
The voltage and amplitude are adjusted and guided to the A / D converter 2, and the voltage level is converted into a digital value at a predetermined sample rate.

The digital data receives a trigger condition satisfaction signal from the trigger circuit 3, and the primary data processing circuit 4 uses the primary memory 5 at a sample rate suitable for the time axis setting.
Written in. The data written in the primary memory 5 is averaged by the secondary data processing circuit 6 and written in the acquisition memory 7.

The data written in the acquisition memory 7 is converted into waveform data by the secondary data processing circuit 6 and then transferred to the waveform capturing circuit 8. Reference numeral 9 denotes a display control circuit, which temporarily stores the captured waveform data in the display memory 10 and causes the display device 11 such as a liquid crystal to display the data.

Reference numeral 12 is a CPU means for managing the entire system, and 13 is an operation portion forming an interface with an operator. The CPU means 12, the operation unit 13, the waveform capturing circuit 8 and the display control circuit 9 communicate with each other via a control bus 14.

In the digital oscilloscope having such a configuration, the attenuation of the noise component superimposed on the input signal Ei, which is the theme of the present invention, will be described. Figure 3 (A)
Shows a waveform when the random noise N1 and the sudden noise N2 are superimposed on the input signal Ei having a continuous waveform of the cycle T.

In normal operation, the rising point TR1 of the first waveform becomes the trigger point, but if the trigger is difficult to apply and is unstable, the rising point TR2 of the second waveform is generated.
May be the trigger point.

Conventionally, the averaging mode described with reference to FIG. 4 has been used as a general means for removing waveform noise. In the averaging mode, the secondary data processing circuit 6 repeatedly captures a plurality of waveform data and averages sample points such that the temporal distances with respect to the trigger point are the same. This means is effective in removing a noise that has a stable trigger or a periodic waveform.

[0009]

On the other hand, when the observing waveform contains a waveform that is hard to trigger or contains sudden noise, the averaging mode is used to display a waveform different from the actual observed waveform. To be done.

For example, consider the case of observing the waveform Ei of FIG. In many cases, the waveform is captured by using the rising point TR1 of the first waveform in the figure as a trigger.
When the trigger point is unstable, the waveform may be captured with the rising point TR2 of the second waveform as a trigger.

An averaging mode waveform obtained by averaging these is shown in FIG. 3 (B). The TR at the center of the display 11 is the trigger point. When the waveform is captured by using the rising point TR2 of the second waveform as a trigger, the normal capture is displayed before the point TR, that is, the waveform indicated by P in FIG. 3B is displayed. Further, the influence of the sudden noise N2 (the level is low because it is averaged) is displayed as a waveform indicated by Q.

It is an object of the present invention to provide a waveform display device capable of observing waveforms by removing random noise and sudden noise when a stable trigger cannot be obtained or in a waveform where sudden noise occurs. .

[0013]

In order to achieve such a object, the feature of the invention according to claim 1 of the present invention is that a history of holding past waveform data for a specified number of triggers in an acquisition memory. Memory means and extraction means for extracting waveform data of the held data at the same time,
And a waveform display means for selecting and displaying arbitrary value data of the extracted waveform data.

A second aspect of the present invention is that the waveform display means selects and displays the median value data in the extracted waveform data.

A third aspect of the invention is characterized in that the waveform display means, when the number of the extracted waveform data is an even number,
The point is to discard the first waveform data or the last waveform data and select and display the median value data.

According to a fourth aspect of the invention, the waveform display means selects and displays one arbitrary waveform data specified by the user from the extracted waveform data.

According to a fifth aspect of the present invention, the designated number of triggers (N) is sufficiently large (N >> M) with respect to the number of noise data (M) that may occur during this number of triggers. It is in the point selected.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is an image diagram of a history memory group to which the present invention is applied, and FIG. 1B is a display screen diagram of median value data of the history memory group.

In FIG. 1A, M is a history memory group, which is held by the history memory means formed in the acquisition memory 7 for the designated number of triggers (N sheets).
From the past waveform data of (averaged),
The waveform data at the same time (t) is extracted.

FIG. 1 (B) shows a display 1 in which the median value data is selected and displayed from the extracted N pieces of plural waveform data.
It is a screen figure of 1. When N is an odd number, (N-1) / 2th sheet is selected as the median value data. The solid line is the waveform of the normal input signal Ei to be displayed, and the dotted line is the signal P due to the unstable trigger and the signal Q due to sudden noise, which is data that is not probabilistically selected as the median value data.

When the median value data is selected and displayed, if the number N of waveform data is an even number, the first waveform data or the last waveform data is discarded, and (N-1) / 2th data is selected. Good. The position of the selection data in the present invention may be essentially any data other than the median data, and the interface can be designed to select and display one arbitrary waveform data specified by the user.

The essential point of the present invention is that, when median value data or one arbitrary waveform data designated by the user is selected from the extracted data group, it is not probabilistically noise-containing data. Therefore, it is necessary to select the designated number of triggers (N) to be sufficiently large (N >> S) with respect to the number of noise data (S) that may occur during this number of times.

FIG. 2 is a table showing data values at time t in the history memory group M. As for the data value, the value of normal data is "1", and the third data and (N
The -1) -th data shows 1.5 due to the superposition of sudden noise.

The setting of the time t can be given to the system by the operator through the interface of the operation unit,
As shown in the screen of FIG. 1B, a time at which noise may be superimposed is selected at a distance from the trigger point.

The functions of the present invention described above are realized by software processing, and the history memory group, the data table and the like can be constructed in the acquisition memory 7, and no additional hardware configuration is required.

Although the digital oscilloscope has been described in the above embodiment, the present invention can be applied to various waveform measuring devices that attenuate and display noise components.

[0027]

As described above, according to the present invention,
It is possible to easily realize a waveform display device capable of observing a waveform by removing random noise and sudden noise when a stable trigger cannot be obtained or in a waveform where sudden noise occurs.

[Brief description of drawings]

FIG. 1A is an image diagram of a history memory to which the present invention is applied, and FIG. 1B is a display screen diagram of median value data of the history memory.

FIG. 2 is a map diagram showing data values in a history memory to which the present invention is applied.

FIG. 3A is a waveform diagram when random noise and sudden noise are superimposed on a continuous-waveform input signal, and FIG. 3B is an observed waveform diagram when an averaging mode is applied.

FIG. 4 is a functional block diagram showing a configuration of a general digital oscilloscope.

[Explanation of symbols]

1 input amplifier 2 A / D converter 3 trigger circuit 4 Primary data processing circuit 5 Primary memory 6 Secondary data processing circuit 7 Acquisition memory 8 Waveform capture circuit 9 Display control circuit 10 Display memory 11 Display 12 CPU means 13 Operation part 14 control bus M history memory group P Unstable trigger signal, Q Signal due to sudden noise

Claims (5)

[Claims] 1. A history memory unit for holding past waveform data for a designated number of triggers in an acquisition memory, an extracting unit for extracting waveform data of the held data at the same time, and an arbitrary value of the extracted waveform data. A waveform display device comprising: a waveform display means for selecting and displaying data. 2. The waveform display device according to claim 1, wherein the waveform display means selects and displays median value data in the extracted waveform data. 3. The waveform display means, when the number of the extracted waveform data is an even number, discards the first waveform data or the last waveform data and selects and displays the median value data. The waveform display device according to claim 1. 4. The digital oscilloscope according to claim 1, wherein the waveform display means selects and displays one arbitrary waveform data specified by the user from the extracted waveform data. Waveform display device. 5. The specified number of triggers (N) is selected to be sufficiently large (N >> M) with respect to the number of noise data (M) that may occur during this number of times. Item 5. The waveform display device according to any one of items 1 to 4.