problem plotting binary file

[lav]

hi, im recording data on a pda using cf-6004 and the attached analogue input vi - the data attached has 700 samples acquired at 10,000Hz, the objected being monitored is vibrating just below 5kHz - this bit seems to work fine

problem - when i come to read the data, fft it and plot it it seems to treat each sample as 1 second and so gives a wrong fft freq value, how do i get around this?

thanks!

andy

[Dennis_Knutson]

When you save the data, you are not saving any timing information. You just have the raw data. In your acquisition, you are just assuming a default sample rate which is maybe not such a good idea either. If you want to stick with assumptions, then when you read the data from the file, create a waveform data type and specify a dt of 1/sample rate before wiring it to the Spectral Measurements function.

For better code, you might want to look at the shipping examples where logged binary data has a header created that includes the sample rate.