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Pico 2000 fast streaming/block mode questions

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Pico 2000 fast streaming/block mode questions

Postby picopico » Thu Apr 22, 2010 5:17 am

Hi, I need to be able to use a picoscope 2205 to collect data of about 100,000 samples or more, with an interval of around 10-100ns between samples.

My question is: is it really possible to use fast streaming to sample at a period less than 1us using the picoscope 2205 model? I tried testing smaller sampling periods in the hundreds of ns range using the C console program, but program seems to hang when it gets to the run_streaming_ns or the get_streaming_last_values functions, once I try operating them in the ns range.

If fast streaming in the ns range is not possible, would it be better to use multiple consecutive block transfers instead? How long would the delay typically take between block transfers?

Many thanks!
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Re: Pico 2000 fast streaming/block mode questions

Postby Robin » Thu Apr 22, 2010 11:35 am

Hi

For these kind of sampling rates, you need to use block mode.

See the programmer's guide for more information on block mode...

http://www.picotech.com/document/pdf/ps2000pg.en-3.pdf

Robin
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Re: Pico 2000 fast streaming/block mode questions

Postby picopico » Fri Apr 23, 2010 9:58 am

Hi Robin, thanks for the quick reply! I still got a few questions though...

I can use block mode to collect a few thousand samples every 10 ns, right? But since I need to continuously collect samples up to 100,000+ data points, I would then have to call run_block and get_values a few times. However, would there be a significant delay between the samples? The programmer's guide says that the driver performs operations before collecting each block of data, which may take up to 50ms.

Also, since the signal that I need to obtain has a repetitive nature, would it be better if I were to use ETS mode instead of ordinary block mode at a lower sampling rate to achieve my goal of obtaining a large amount of samples, at a high effective sampling rate?

Thanks again in advance!
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Re: Pico 2000 fast streaming/block mode questions

Postby Robin » Fri Apr 23, 2010 12:11 pm

Hi

As the manual suggests, there is a gap between blocks of data that is the time taken for data to be transferred from the scope's memory to the PC. If you want to collect a large number of samples at a high sampling rate, then you need a scope with more memory. With the 2205, you either need to lower your sample rate to 1 MS/s or the number of continuous samples you wish to collect to 16,000.

I'm not sure ETS will help you unless you need an effective sampling rate greater than the sampling rate of the scope. You are still limited by the size of the scope's memory.

Robin
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Re: Pico 2000 fast streaming/block mode questions

Postby picopico » Sat Apr 24, 2010 11:12 pm

Ok, thanks for the clarifications, Robin!
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