high sampling rate

Forum for discussing PicoScope version 6 (non-automotive version)
baffoun
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Joined: Wed Mar 27, 2013 5:39 pm

high sampling rate

Post by baffoun »

Hi,
i have use PicoScope6404B to make measurements with a sampling rate of 312,5MS/s during 0,5s. so that i get about 156MSamples. When i load the converted data in .mat file, i get the Warning: "Unable to read some of the variables due to unknown MAT-file error.". I have try the release 6.6.50 and the latest 6.6.57.

in .csv i get just the first 1MSamples o f my data.

What i did wrong ?

thanks, Bassem

Hitesh

Re: high sampling rate

Post by Hitesh »

Hello Bassem,

We are aware of an issue relating to saving large files to a .mat format.

If you have any items such as filtering turned on, please turn them off and try saving the file again. You can also try the latest version of the PicoScope Beta software from

http://labs.picotech.com/

Are you loading the files into MATLAB or another application?

With csv files there is a limit of 1.048 million samples per channel owing to a limitation in MS Excel.

I hope this helps.

baffoun
Newbie
Posts: 0
Joined: Wed Mar 27, 2013 5:39 pm

Re: high sampling rate

Post by baffoun »

Hello Hitesh,

also with the latest version i get an error message when loading the converted file in MATLAB.
Please help !

the PicoScope software allows spectrum bins up to 1048576, so that only 2MSamples of my data (about 156MSamples) will be used and the rest will be ignored. Therefore i want to calculate the FFT in Matlab. Furthermore in the spectrum view the frequency axis is unfortunately not logarithmic.

Bassem

Hitesh

Re: high sampling rate

Post by Hitesh »

Hello Bassem,

If the original .psdata file is less than 5MB, please e-mail it to support@picotech.com

Otherwise, please upload it to a filestore site or let me know and I can provide you with somewhere to upload it on our filestore site.

Thanks,

baffoun
Newbie
Posts: 0
Joined: Wed Mar 27, 2013 5:39 pm

Re: high sampling rate

Post by baffoun »

Hello Hitesh,

because of the high sampling rate the .psdata file is 158MB big. Please tell me, how can i upload it in your filestore site.

thanks for your support.

Bassem

baffoun
Newbie
Posts: 0
Joined: Wed Mar 27, 2013 5:39 pm

Re: high sampling rate

Post by baffoun »

Hello Hitesh,

i have already uploaded a test-file with a half of the sampling rate (=156,3MS/s), so that the file is below 100MB

i get this error from Matlab (7.11.0, R2010b):

??? Error using ==> load
Unknown text on line number 1 of ASCII file
test.mat
"".

Error in ==> importdata at 195
out = load('-ascii',FileName);

Error in ==> uiimport>runImportdata at 432
[datastruct, OTextDelimiter, OHeaderLines] = ...


Thank you for your help, Bassem

Hitesh

Re: high sampling rate

Post by Hitesh »

Hi Bassem,

I've picked up the file and the bug does not appear to have been fixed yet.

I will pass on a request for one of our Development Engineers to take a look.

Are you looking to post-process this data in MATLAB? It is possible to write MATLAB scripts that use the dlls in the Software Development Kit in order to capture data. Guidance is provided in the following area on the forum:

http://www.picotech.com/support/forum71.html

Best wishes,

baffoun
Newbie
Posts: 0
Joined: Wed Mar 27, 2013 5:39 pm

Re: high sampling rate

Post by baffoun »

perhaps it is a tip, how your Development Engineers can fix the conversion error of a measured data to .mat file !!!!

i have another question:
as i duplicate my data (156MSamples) to a reference waveform, the .psreference file was just 3MB big and the .mat file contains only 4,2MSamples. The frequency spectrums of the original and the duplicated data in Picoscope are also different (i see peaks in the duplicated data every 370kHz) --> i think the duplicate data are undersampled, isn't it ??
-->
Hello Hitesh,

i have try the export function of a reference waveform in Matlab and it works. Matlab can read the data without any error --> perhaps it is a tip, how your Development Engineers can fix the conversion error of a measured data to .mat file !!!!

i have another question:
as i duplicate my data (156MSamples) to a reference waveform, the .psreference file was just 3MB big and the .mat file contains only 4,2MSamples. The frequency spectrums of the original and the duplicated data in Picoscope are also different (i see peaks in the duplicated data every 370kHz) --> i think the duplicate data are undersampled, isn't it ??