Re: [Discuss-gnuradio] min. decimation value

[Eric Blossom]

On Sun, Dec 03, 2006 at 04:03:08PM -0600, Shravan Rayanchu wrote:
> Hello everyone,
> 
> My understanding is that the decimation value for the fpga has to be
> between [4, 256]. In usrp_spectrum_sense.py, when I set the decimation
> values to 16 or 8 (spanning 4Mhz and 8Mhz chunk at once), then
> m.data[0] ...m.data[255] print out fine. However, when I set the
> decimation to 4 (i.e. we will be observing a chunk of 16 Mhz), then
> all the  values data[0] ..data[255] are ZERO.
> 
> I am trying to understand why is this the case .. is it that the USB
> is not fast enough for decimation value of 4? I get some "u0"s printed
> out even when I run for decimation values of 16 and 8 ... is this a
> cause of concern?

decim = 4 is only valid if you're using 8-bit I&Q across the USB.
Otherwise it won't fit.  Use decim = 8.

Eric