Re: [Discuss-gnuradio] USRP RX Decimation Rate

[Matt Ettus]

Brian Padalino wrote:
> On 4/21/07, Eng. Firas <address@hidden> wrote:
> > Hi All,
> >
> > I'm  a new USRP user. Kindly, I will be very appreciated if someone 
> > could
> > tell me what is the decimation range of the USRP RX path? I'm really
> > confused. Is it linear range from [1,2,3,4,.....] ?or it is power of 2
> > [2,4,8,16,...]?
>
> It's linear and within 4 to 128 inclusive, according to
> cic_dec_shifter.v located here:
>
>    
> http://gnuradio.org/trac/browser/gnuradio/trunk/usrp/fpga/sdr_lib/cic_dec_shifter.v 

The CIC decimator does 4 through 128, but this is followed by a halfband 
decimator which multiplies this by a factor of 2.  Thus, it only does 
multiples of 2.  4, 6, 8, 10, 12, 14, 16, 18. 20, etc.   Up to 256 total.

Matt