Re: [Discuss-gnuradio] Problem with N200 and waterfall display in grc

[Marcus D. Leech]

On 16/08/2011 3:20 PM, Isaac Gerg wrote:
> I fixed it by ensuring that the sample rates were correct in the 
> blocks.  I was requesting a fs of 100 Hz but was getting something 
> around 190kHz. Once i got these numbers all synced up (to the 190kHz) 
> the blocks worked as expected.
>
> Isaac
The Fs on the FFT and Waterfall graphs is used to calculate the labels 
for the  X-axis, and also some internal decimation, but it doesn't force the
  incoming stream to be arriving at that sample rate.  It must match 
the actual sample rate, which on the N2XXX is a minimum of
  100e6/512 = 195312 Sps.

If you need to process samples at some rate other than one of the 
properly-decimated rates coming out of a UHD source block, you'll
  have to resample within the flow-graph.  I like to use the fractional 
interpolator myself.