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How to continuously sample at high sampling rate

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How to continuously sample at high sampling rate

Postby Amy » Wed Aug 31, 2011 2:20 pm

Hi,

We have the PicoScope 4224. We are trying to capture data at a sampling rate of 10 MSps from one channel for about 2 minutes, without aggregation, without any gaps in the data.

We first tried your sample code in PS4000con.c, making changes to the streaming mode to change the sampling rate and to remove aggregation, but we have not been able to capture any data. I realize that we are pushing the limits of what this oscilloscope can do.

My questions are:
1. What are you recommendations for the specs for the host PC?
2. Can streaming mode capture at this rate WITHOUT losing any data? I realize there is overhead with copying the data from the buffer, but I thought maybe sizing the buffer appropriately (smaller) would reduce the amount of time, but then again, I don't know what the overhead is for calling ps4000GetStreamingLatestValues().
3. Is there a recommended buffer size for this sampling rate in streaming mode?
4. What is your recommendation for which mode to use? Another option would be to use block mode, using two buffers, and create one thread to write to one buffer while another reads from the other buffer. Is this a good way to go?

I'm just trying to get a feel for which direction to go in before I get in too deep into a method that won't work.

Thanks!

Amy
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Re: How to continuously sample at high sampling rate

Postby Martyn » Wed Aug 31, 2011 3:00 pm

The following pdf gives some details on fast streaming and may help

http://www.picotech.com/support/kb/kbfiles/PicoScopeUSBStreaming.pdf
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Re: How to continuously sample at high sampling rate

Postby Amy » Wed Aug 31, 2011 3:12 pm

Hi, Martyn,

I have read the document. However, the document is vague with regards to performance. I have been able to capture data using the ps4000con.c application with the original parameters. It was when I changed the parameters (no aggregation, more samples, higher sampling rate), that we don't get any data. Would the code, as written, support a 10 MSps rate? I have my doubts since it also prints to a file, which is really slow. Have you been able to use this code at higher sampling rates?

Thanks,

Amy
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