Re: [Discuss-gnuradio] USRP Gain

[Brian Padalino]

On Fri, Sep 5, 2008 at 5:04 PM, Richard Jaeger <address@hidden> wrote:
> Well, if the gain is really in (0.5, 1), that makes my missing gain
> situation worse.  I would be hunting for more than 20,000 in that case.
> Also, it is inconsistent with my measurements that show that the gain
> increases by a total of 26 dB as the decimation rate
> is changed from 96 to 256.
>
> ---
>
> Where is the shifter you are referring to?   Is it in a non-recursive
> implementation of the CIC filter?

If you take a look here:

    
http://gnuradio.org/trac/browser/gnuradio/trunk/usrp/fpga/sdr_lib/cic_dec_shifter.v

All that's happening here is the decimation rate chooses a different
slice of the output of the CIC filter.  Once you go past a decimation
rate of 107, the bitgain becomes 28 and stays there no matter what.

Brian