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Only 1 division saved instead of full window

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Only 1 division saved instead of full window

Postby stevenvh » Sat Mar 21, 2015 3:45 pm

I'm using a PicoScope 3000 MSO.

I'm trying to log data over a period of 100 seconds, so I set the time scale to 10s/div. I want 100k samples per second, so I set the sample rate at 10MS. Trigger set to single. Seems to work all right, and when I'm saving the data as text I get the expected warning that my file will be huge (380 MB). I'm OK with that.
But when I see the textfile it's only 25 MB big, and only contains 1 megasample, so that's for the first division only, not the full screen. What am I doing wrong?
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Re: Only 1 division saved instead of full window

Postby Hitesh » Mon Mar 23, 2015 2:14 pm

Hi stevenvh,

There is a limit of just over 1 million samples (1048576 to be precise) when exporting to .csv or .txt file format.

You would have to export the data to .mat format and use a program capable of reading the .mat v4 format in order to extract the data out.

Are you looking to process the data using a third party application?

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Re: Only 1 division saved instead of full window

Postby stevenvh » Mon Mar 23, 2015 4:46 pm

Thanks Hitesh. I want to read as much data as possible in one window, avoiding the gaps in the data going from one window to the next.
I plan to process the data in a Delphi program I'll write myself. I don't know how to read .mat data, but maybe I can find something. What's the reason why I can save the data as .mat, but not .txt? Does it have to do with filesize? In that case it might help when the timestamps only show significant data. For instance:

9.15600043 1
9.15700043 1
9.15800043 0
9.15900044 0
9.16000044 0

is sample 1 sample per ms, so

9.156 1
9.157 1
9.158 0
9.159 0
9.160 0

should suffice, and would make the data more readable. I don't need the nanoseconds! (Which should be zero, anyway. Where does this deviation come from?)
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Re: Only 1 division saved instead of full window

Postby stevenvh » Mon Mar 23, 2015 5:20 pm

I found that Mathematica should also be able to read .mat files, but when I try to Import[] I get an error "insufficient data found for MAT format". Mathematica claims it can read version 4 and 5 mat files. What gives? Is the data saved as .mat nonstandard?
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Re: Only 1 division saved instead of full window

Postby Hitesh » Wed Mar 25, 2015 1:56 pm

Hi stevenvh,

The format of the time values is possibly down to floating point accuracy but I have referred this for investigation.

The data is exported to Level 4 MAT-File Format. You can find information via the following document that The MathWorks provide:

http://www.mathworks.co.uk/help/pdf_doc/matlab/matfile_format.pdf

How many samples are there per channel in the data file?

Please note that Pico Technology is not responsible for the content of third party sites.

Regards,
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Re: Only 1 division saved instead of full window

Postby stevenvh » Wed Mar 25, 2015 5:14 pm

Hi Hitesh,
I posted a question on mathematica.stackexchange.com about the .MAP format. Turns out there's a bug in Mathematica, with the bug fixed the file reads fine.
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Re: Only 1 division saved instead of full window

Postby Martyn » Thu Mar 26, 2015 1:56 pm

Thanks for letting us know
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