Jennings Posted June 16, 2006 Report Share Posted June 16, 2006 Using the spectrogram function in Labview, I'm getting a weird cutoff in my graph. I'm plotting frequency v time, and on the frequency side, the graph goes up to a certain threshold, and then nothing above that threshold, even though I'm certain that I'm recording frequencies higher than that. Is there any known problem or limitations with the NI_gmath.lvlib:STFT Spectrogram.vi function? Any suggestions? Thanks! Jennings Quote Link to comment
bbean Posted June 17, 2006 Report Share Posted June 17, 2006 Using the spectrogram function in Labview, I'm getting a weird cutoff in my graph. I'm plotting frequency v time, and on the frequency side, the graph goes up to a certain threshold, and then nothing above that threshold, even though I'm certain that I'm recording frequencies higher than that.Is there any known problem or limitations with the NI_gmath.lvlib:STFT Spectrogram.vi function? Any suggestions? Thanks! Jennings Are you using a daq card and DAQmx to sample the data? The only time I have seen this is when I set the sample freq. too low by accident. I've seen NI's Express VIs automatically cutoff anything above the Nyquist freq (which makes sense) Quote Link to comment
Jennings Posted June 20, 2006 Author Report Share Posted June 20, 2006 Are you using a daq card and DAQmx to sample the data?The only time I have seen this is when I set the sample freq. too low by accident. I've seen NI's Express VIs automatically cutoff anything above the Nyquist freq (which makes sense) No, I don't have any daq hardware hooked up. I am taking a binary file and converting it to a wave file, which I want to analyze via the spectrogram function. Is there any caveats with this process? Quote Link to comment
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