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PICOSCOPE 3206A transient noise

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PICOSCOPE 3206A transient noise

Postby Epa » Sat Sep 14, 2013 10:14 am

Hello,

I'm new to Pico Scope and i'm using picoscope 3206A for transient measuremets, with the help of Tektronix P6015A high voltage probe. I'm just trying to familiarize with the devices and measuring switching transients. Every time i get a transient (or even pure 230v supply wave directly provided into the scope, reducing to 1000x) i get a noised signal like here
transient.png
The screen print i got.


Please tell me how i can obtain smooth (without noises, i mean just a single line sine wave) sign al using the probes and scopes i have. I tried a lot. DO i have to make my own external filter for this simple task ?

Thanks in advance.
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Re: PICOSCOPE 3206A transient noise

Postby Martyn » Mon Sep 16, 2013 9:22 am

Which version of the Picoscope software are you using ?

You can apply a low pass filter, or use Resolution Enhancement, from the Channel Options menu to smooth the waveform.
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Re: PICOSCOPE 3206A transient noise

Postby Epa » Tue Sep 17, 2013 5:25 am

Thanks for the reply. I'm using the version "picoscope 6".
What you mean by,

Martyn wrote: You can apply a low pass filter, .


is it hardware filter to make or software side thing to do using the same version ? Can you please provide me guides to make it ? any documents :o :shock:
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Re: PICOSCOPE 3206A transient noise

Postby Martyn » Tue Sep 17, 2013 6:14 am

It is in the software you have. Click on the Channel Letter with the Arrow on it "Channel Options" and you should see it listed
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Re: PICOSCOPE 3206A transient noise

Postby Epa » Fri Sep 20, 2013 6:58 am

Thanks a lot. Sorry for my sometimes late responses cz I'm a part time researcher.

I tried it working. but seems the software stucks at above 3kHz.
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Re: PICOSCOPE 3206A transient noise

Postby Epa » Sat Sep 21, 2013 7:05 am

Ok now i got cleared the signal from noices and have smooth sinal. Transients are even better. But the two more problems arisned.

1. The software does not allow me to increase the sampling rate greater than 2MS (Marked as 1) As soon as i increase it and come back to run mode it automatically set 2MS.

2. The properties plane completely irrelevant for my settings ? (Marked as 2)

Image

Please instruct me why this happen ....
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Re: PICOSCOPE 3206A transient noise

Postby Martyn » Mon Sep 23, 2013 7:02 am

The properties pane will always show exactly how the scope has been set. The software will make an appropriate choice based upon the requested number of samples and the specified collection time across the screen.

As soon as you apply a lowpass filter, or resolution enhancement, the number of samples is limited to 2MS to avoid slowing down the software, and to help maintain a good waveform update rate. It is possible to collect the data at the full rate and then when collection has stopped, and the data stored to disc, apply the filter to the collected data.
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Re: PICOSCOPE 3206A transient noise

Postby Epa » Sat Nov 02, 2013 7:08 am

Thanks for early responses. I have some more to clarify.

1.
Image

The above is a transient waveform i have obtained using my high voltage probe and Picosciope 3206A. Only at lower sampling rates (above picture is at less as 5MS and 340v trigger) i can have 'burst's even as can be seen. But as i increase the sampling rate only one transient is shown by capture. Like below (which is taken at 200MS and 400v trigger value ),
Image

All i can understand is, as increment of sample rate the software only captures the trigger exceeding transient and records it only, without wasting memory to save larger bursts that do not exceed transient. Isn't it ? is there any tactical way to save those bursts also keeping the high sampling rate ?

2. When i use the alarm feature and save the waveforms to my computer harddisk, setting an alarm and saving buffer options, what is the trigger delay it uses ? As per to PicoScope 3000 series data sheet,
triger re-arm time < 2 μS on fastest timebase
what is the meaning of that ? Or the system re-capture next pulse (once exceeds the trigger value set) after what ever the time taken for saving early capture ?

3. This prolem once i asked,
The properties plane completely irrelevant for my settings ? (Marked as 2)
and the answer given not clear to me,

The properties pane will always show exactly how the scope has been set. The software will make an appropriate choice based upon the requested number of samples and the specified collection time across the screen.

So which i should trust ? The value i set or value in the properties pane ?

Sorry for lengthy questions, but please help me to figure out ! Thanks.
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Re: PICOSCOPE 3206A transient noise

Postby Martyn » Thu Nov 07, 2013 12:11 pm

1. In the first trace the trigger diamond is within the trace range, so you will get multiple trigger events. In the second trace the trigger diamond is outside the normal waveform so you will only get occasional triggers when there is a speke.

2. Triogger re arm time means the time taken before the scope is ready to look for an new trigger event. The statement
triger re-arm time < 2 μS on fastest timebase

refers to the rapid block mode of operation where multiple traces are collected to the memory of the scope without downloading them to the PC.
The re arm time for block mode where you capture a trigger event, download the data to the PC, and then rearm and restart the scope, will be less than 60ms depndent upon the PC and what it is doing as well.

3. Trust the values in the property pane, these are what the scope is using. The values you set at the top are what you would like. However due to how the scope works and how much data is needed to display on a screen some settings are not possible.

For future reference if you use File->SaveAs and save the current waveform we can then see all the information, including the data, and can run it up in Picoscope 6 here and see exactly what you do. The pictures you are posting do not show enough detail to truly comment.
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