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From 04:00 PM CDT – 08:00 PM CDT (09:00 PM UTC – 01:00 AM UTC) Tuesday, April 16, ni.com will undergo system upgrades that may result in temporary service interruption.
We appreciate your patience as we improve our online experience.
04-25-2007 04:55 PM
04-25-2007 05:03 PM
04-25-2007 06:43 PM
04-26-2007 10:12 AM
Hello,
Thank you for the suggestions. Writing unscaled I32 more than cut my file size in half. Much appreciated.
What is the advantage of saving Waveforms instead of unscaled at such a size cost? They must only be useful for short data collections at low rates?
Best,
Frenk
04-26-2007 02:52 PM
04-26-2007 03:51 PM
Hello,
Hmmm... I've run into an unexpected problem. I'd like to scale the unscaled data from DAQmx for some calculations during the data collection, but it isn't scaling the way I would have expected.
My range is +/-10V and the largest unscaled numbers for data filling that range are very roughly about +/-125000. I would have expected them to approach 2^31 (one bit for sign)!! How can one scale this data?
Also, my saved TDMS file doesn't seem to have the information that "Cont Acq&Graph Voltage - Graph Unscaled Data from File (TDMS).vi" needs to scale it.
Regarding I16, my data is unusual in that it contains a signal of interest that is about 80 dB below the stimuli that are also in the measurement. For that reason I need the full I32 to avoid excessive quantization error in the signal of interest.
Thanks again!
Frenk
04-26-2007 04:00 PM
04-26-2007 04:41 PM
04-26-2007 05:42 PM
Hello,
I just tried again and I'm not quite there...
My input signal was about +/-1.5V and the unscaled values were about +/-95000.
The input range was +/-5 V.
I would have expected the scaling to go like this:
95000 / (2^17-1) * 5 V = 3.6 V for my signal amplitude (instead of the correct 1.5 V)
Any thoughts? Thanks for all the help,
Frenk
04-26-2007 06:01 PM