JPH0446216Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an improvement of a waveform storage circuit in a waveform storage device such as a digital storage oscilloscope.

[Prior art and its problems]

In conventional waveform storage devices, the input signal is always A/
A predetermined amount of the D-converted and digitized input signal is unconditionally written into the memory after a trigger is applied. During this time, a trigger occurred, but I ignored it. This method is fine if the observation target is operating normally. However, when an abnormality occurs in the input signal, it is necessary to observe and analyze the waveform at this time, but the trigger often fails, and therefore observation is extremely difficult with conventional waveform storage devices.

〔the purpose〕

This invention is characterized by ignoring the input signal level when it is normal, and storing and displaying it only when an abnormality occurs.The purpose of this invention is to easily capture abnormal phenomena and facilitate observation and analysis. It's about getting used to it.

〔Example〕

In this invention, in order to observe the waveform when an abnormality occurs, the input signal from the previous trigger point is converted into an AD signal.
It was created with the focus on the point that all you have to do is memorize it. In other words, when the interval between triggers is Δt, if a trigger occurs within Δt, the memory is rewritten from the beginning, and only when the trigger does not occur, it is displayed.

An embodiment of the present invention will be described below with reference to the drawings. Examples are 1: input signal, 2: attenuator, 3:
AD conversion circuit, 4: trigger signal generation circuit, 5: counter, 6: signal indicating the end of AD conversion, 7: address signal corresponding to the count value, 8: signal indicating that the number of data for one screen has been counted, 9,1
1: memory, 10: data transfer circuit, 12: display control circuit, 13: cathode ray tube, 14: 11 is a signal indicating that all data transfer has been completed.

Next, this operation will be explained. After input signal 1 is brought into an appropriate range by attenuator 2,
The signal is input to the AD conversion circuit 3 and the trigger signal generation circuit 4. The AD conversion circuit 3 performs AD conversion at predetermined intervals and writes the results into the memory 9. The address is determined by address signal 7. Trigger signal generation circuit 4 determines the input level and outputs a signal indicating that a trigger has been applied to counter 5. The counter 5 counts the signal 6 indicating the end of AD conversion and outputs the address signal 7, but when a trigger is applied, it is reset and starts counting again from the initial value.
In this way, data from the time when the last trigger is applied is always written into the memory 9. Therefore,
In the state where the trigger is applied before AD conversion for one screen is completed, that is, in the normal state, memory 9 is 1.
The screen's worth of data is always rewritten before it is stored. Then, when the trigger is no longer applied, the AD conversion for one screen is completed, and the counter receives the signal 8.
Output. When signal 8 of memory 9 turns ON,
From then on, no writing will be performed until it is turned OFF. The data transfer circuit 10 transfers the contents of the memory 9 when the signal 8 is turned on to the memory 11, and outputs the end signal 14 when this is completed. The counter 5 receives the end signal 14.
When it turns ON, counter 5 is reset and signal 8 is turned on.
Turn it OFF and start counting and writing AD conversion results again. The display control circuit 12 reads out the contents of the memory 11 and displays them on the cathode ray tube 13. In this way, only the waveforms after the last trigger are displayed on the cathode ray tube 13.

That is, if the input signal 1 is normal, data after the trigger is stored in the memory 9, but the contents of the memory 9 are rewritten with data input by the next trigger. If the input signal 1 is normal, this operation is repeated, so no waveform is displayed on the cathode ray tube 13. If there is an abnormality in the input signal 1 (an abnormality that causes the trigger to no longer be applied), the data after the last trigger will be stored in the memory 9, but since no trigger will be applied during this time, the memory 9 will be in a full state. become. When the memory 9 becomes full, the input data is transferred to the display control circuit 1 as described above.
It is displayed on the cathode ray tube 13 via the second etc.

In conventional waveform storage devices, the AD conversion interval is usually selected so that multiple peaks are displayed within one screen, and in this case, the trigger is applied multiple times.

In this embodiment as well, by doing the same, the waveform when an abnormality occurs can be reliably stored and displayed.

〔effect〕

As described above, according to the present invention, it is possible to reliably detect and display the occurrence of an abnormality accompanied by a decrease in the signal level.
Therefore, it is effective in analyzing such abnormal phenomena, especially when they occur only rarely. It is also effective in detecting and analyzing abnormalities in systems that require unmanned operation.

[Brief explanation of drawings]

The figure is a block diagram of an embodiment of the present invention, and its main parts are 2...attenuator, 3...AD conversion circuit, 4...trigger signal generation circuit, 5...counter, 9, 11...memory, 12... . . . Display control circuit, 13 . . . Braun tube.

Claims (1)

[Scope of utility model registration request] The input signal is input at the timing of the trigger signal from the trigger generation circuit, and the attenuator converts the input signal within an appropriate range.
Counts the number of AD conversions, writes the AD converted results to the address in memory according to the number of conversions, and when a predetermined amount is reached, stops writing, transfers the data to the display memory using the transfer circuit, and displays this content. Each time a trigger is applied to the waveform storage device that is displayed on the cathode ray tube in the control circuit, the trigger generation circuit resets the counter, so the waveform is stored and displayed only if no trigger is applied until the counter value reaches a predetermined value. A waveform storage device characterized by: