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