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more time axis on Picolog spreadsheets

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more time axis on Picolog spreadsheets

Postby lurieea » Tue Nov 09, 2004 2:18 am

After collecting data with my ADC-11 at 10 ms sampling rate in real time continuous mode, I see in the spreadsheet that the time column says Time (ms) 9, 25, 25, 40, 40, 56, 71, 71, 87, etc. It should read 10, 20, 30, 40, 50, etc. I also see a similar problem when I sample at 1 or 100 ms. It works fine when I sample at 1 sec.

Am I really sampling at 10 ms, or am I sampling at some random inerval approximating 10 ms?

I am using PicoLog 5.10.3. I am not using the beta version because of a difficulty encountered in fast block mode (see my post of Oct 6).

Help!
lurieea
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Postby Sarah » Tue Nov 09, 2004 12:19 pm

Hi

Thank you for your post, I am sorry to hear that you have been having this problem.

The reason that you are seeing what you are seeing is that the ADC-11 is controlled by the windows clock. When you sample at quick time intervals windows cannot clock fast enough for it so it makes up for the missed samples be duplicating some others.

The best way to get round this is to use our Pico USB to Parallel port adaptor as this will then provide the clocking for the unit rather than windows, and your results will be smoother. Please note that only our adaptor works with our products.

Hope this helps

Best Regards
Sarah
 

Postby lurieea » Tue Nov 09, 2004 4:41 pm

You write that "it makes up for the missed samples be duplicating some others." But the voltage readings themselves are not duplicated, i.e. it does not appear that the same voltage is written to files twice. Plotting volts vs. sample number (not time) is smooth.

Also when it displays on the Pico graph, the time axis distribution appears smooth, not doubled in any places. Does the graphing routine assume equally spaced time increments?
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Postby Sarah » Wed Nov 10, 2004 11:07 am

Hi

Thank you for the extra information.

I think the easiest way for me to investigate this further would be to see one of your files that shows this problem. If you could send a file to support@picotech.com which shows the problems that you describe then we can look into it further. Please remember to put a brief explaination as to the problem in the body of your email so that we know what the file is in reference to.

Best Regards
Sarah
 


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