JPS6394166A - Waveform measuring instrument - Google Patents

Abstract

PURPOSE:To take a measurement relating to the level variation of an analog signal, i.e. data variation of a digital signal by providing a trigger circuit, a memory control circuit, etc. CONSTITUTION:The trigger circuit 3 outputs a trigger to a memory circuit 5 by detecting the variation of the output of an A/D converter 2 corresponding to set conditions. Then the circuit 5 when applied with the trigger stops the storage data and outputs a control signal for stopping the storage after the specific number of data after the point of the application of the trigger are stored to a memory 4. Thus, the measurement relating to the data variation of the digital signal is easily attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a waveform measuring device, and more particularly, to improvements in a digital waveform measuring device.

[Prior Art] Waveform measurement devices use an analog method to directly display or record an analog signal waveform, or a flexible method in which the analog signal is converted to a digital signal using an A/D converter and stored in a memory. It can be roughly divided into two types:

Analog devices are effective for observing the waveform itself and for long-term recording.

On the other hand, digital devices edit measurement data.

It is effective for treating itching, outputting data to computers, etc., and is used in various fields.

Incidentally, in such a digital waveform measuring device, the storage operation of a digital signal in a memory is controlled in accordance with a trigger.

That is, trigger detection in conventional digital waveform measuring devices is performed by digitally comparing a digital signal converted by an A/D converter with a trigger level set as a digital value.

[Problems to be solved by the invention] However, according to such a conventional configuration, since the trigger is set by level, the level of the digital signal changes to the trigger level depending on the rising or falling setting. Each time the trigger is exceeded, data will be captured.When making measurements related to rise time or fall time, search multiple stored data and select the data that meets the conditions. It is inconvenient to have to take it out.

The present invention has been made with attention to these points, and its purpose is to realize a waveform measurement device that can easily perform measurements related to level changes of analog signals, that is, data changes of digital signals. There is a particular thing.

[Means for Solving the Problems] The present invention achieves the above object by providing a waveform measuring device configured to convert an analog signal into a digital signal using an A/D converter and store the digital signal in a memory. The present invention is characterized in that it includes a trigger circuit that detects a change in a digital signal and activates a trigger, and a memory control circuit that controls memory storage operations in accordance with the trigger.

[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, 1 is an input terminal for an analog signal to be measured, and is connected to an A/D converter 2. In FIG. The output signal of the A/D converter 2 is applied to a trigger circuit 3 and also to a memory 4. The output signal of the trigger circuit 3 is applied to the memory control circuit 5, and the output signal of the memory control circuit 5 is applied to the memory 4 as a control signal.

Here, the trigger circuit 3 has trigger condition data consisting of lower limit value data, upper limit value data of the trigger level, and time data related to changes between the lower limit value and the upper limit value, as shown in FIG. 2, for example. Memories 6 to 8 for storage are provided, and a trigger generation circuit 9 is provided that generates a trigger when the output signal of the A/D converter 2 satisfies these trigger conditions.

In such a configuration, the trigger circuit 3 outputs a trigger to the memory control circuit 5 by detecting a change in the output signal of the A/D converter 2 according to the setting conditions. The memory control circuit 5 sends a control signal to the memory 4 to stop storing data when a trigger is applied, or to stop storing data after a predetermined number of data have been stored from the time when a trigger is applied. Output to.

FIG. 3 is a waveform diagram showing a specific example of such an operation.

In Fig. 3, (a) sets the lower limit value of the trigger to ■1 and the upper limit value to v2, and the analog signal is set to the upper limit value V2.
An example is shown in which storage of data in the memory 4 is stopped after a certain period of time Ta has elapsed since the time Ta exceeds the time limit. Here, assuming that the data storage capacity of the memory 4 is large enough for the data stored during time l''a, the waveform data before and after the trigger is output can be completely stored in the memory 4. Therefore, it is possible to reliably obtain analog signal waveform data that satisfies the conditions.

Next, in (b), the lower limit value of the trigger is set to V, the upper limit value is set to ■4, and after the analog signal exceeds the lower limit value ■3, the upper limit value V4 is set in a time Td shorter than the fixed time Tb. If it exceeds ++!, it is determined that it is a bus, and the data stored at the time the trigger is output is valid, and the upper limit is reached at Tc, which is longer than the fixed time Tb. An example is shown in which if it exceeds I V d, it is determined to be a failure and the data stored at the time the trigger is output is invalidated. This results in
Only path data can be collected efficiently.

With this configuration, a trigger can be applied according to changes in digital signal data, so that various calculation processes and analyzes can be easily performed by a computer.

In the above embodiment, an example of measuring a rising edge has been described, but it is equally effective for measuring a falling edge.

Furthermore, the present invention is not limited to measuring the rising edge or falling edge, but may output a trigger by detecting a combination of bit strings of digital signal data or a change in the combination of bit strings.

[Effects of the Invention] As explained above, according to the present invention, it is possible to realize a waveform measuring device that can easily measure changes in the level of an analog signal, that is, data changes in a digital signal, and the practical effects are significant. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a specific example of a trigger circuit used in the present invention,
FIG. 3 is a waveform diagram for explaining the operation of FIG. 1. DESCRIPTION OF SYMBOLS 1... Input terminal, 2... A/D converter, 3... Trigger circuit, 4... Memory, 5... Memory control circuit,
6-8 Figure 1 (a)]

Claims (1)

[Scope of Claims] A waveform measuring device configured to convert an analog signal into a digital signal using an A/D converter and store it in a memory, comprising: a trigger circuit that detects a change in the digital signal and applies a trigger; 1. A waveform measurement device comprising: a memory control circuit that controls memory storage operation in accordance with a trigger.