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variation in Data Set Length between saved files

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variation in Data Set Length between saved files

Postby Bob Mehew » Tue Jan 23, 2018 11:13 am

I have just found that if I set Picosoft to a single trigger and run for just one page to collect a notional 1 Mega set of samples, when I save the data in the .mat format I get 1,000,000 samples but when I save the data in the .csv format I get 1,000,004 samples. Whilst I see Picosoft disclaims a precision on the number of samples, I had expected to see the same number when saved in different formats from the same .psdata file. Is this a known bug? Fortunately I can step around it now I know about it.
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Re: variation in Data Set Length between saved files

Postby Hitesh » Thu Jan 25, 2018 10:05 am

Hi Bob,

The effect you are seeing is likely to be expected behaviour, with the additional number of samples used to help with alignment on the screen (e.g. when triggers are in use).

Which version of the PicoScope 6 software are you using? If you are able to send a PicoScope 6 data file to support@picotech.com, we can run a check on the export.

Regards,
Hitesh

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Re: variation in Data Set Length between saved files

Postby Bob Mehew » Thu Jan 25, 2018 12:14 pm

I am using software version: 6.12.9.2917 . I note one also sees some padding of the file if one records less than a full wave form and then tries to save it as a full wave form using the Save as / all wave forms command. I will send a file to you but it occurs what ever the data source. (I found out about this when I was trying to sort out taking the data in a Python program and needed to check values between a .mat and .csv version of the data. It appears one gets a small and trivial difference due to I presume binary v decimal formatting of data.)
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Re: variation in Data Set Length between saved files

Postby Hitesh » Thu Jan 25, 2018 4:31 pm

Hi Bob,

I have responded via your support ticket and am posting back on here to provide clarification for other Users.

Extra samples are usually captured for alignment of the waveform in the window and also for processing (e.g. resolution enhancement and filtering).

With the .mat files, we have an ExtraSamples parameter which indicates the number of extra samples.

I have reported a bug in relation to this.

Regards,
Hitesh

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