On 04/18/2010 05:16 PM, David Barton wrote: > Hi, > > In GRC I hooked up a signal source with a 100kHz sampling rate > directly to a FFT sink. I accidentally listed the FFT sampling > frequency as 200kHz. I noticed that it did not complain and all it did > was shift the actual signal source frequency by a factor of 2. So my > guess would be that the FFT block is not actually using the sampling > rate parameter in the FFT calculations except to just scale the > frequency axis. Is that accurate? > > Thanks, > Dave > To a first approximation, yes.
The other thing I think the FFT graphical sink uses the sample rate for is to calculate the required "keep-one-in-N" for maintaining the desired screen update rate. But the FFT itself onlys knows about a vector of samples, what they mean, in a temporal sense is rather outside the scope of the FFT calculation. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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