Re: [Discuss-gnuradio] USRP2+WBX - How to use precisely an 8 MHz band?

[Marcus D. Leech]

On 11/11/2010 10:46 AM, Vladutzzz wrote:
> Dear all,
> I am trying to receive with my USRP2 + WBX daughterboard a signal band of
> precisely 8 MHz in order to measure it's power.
> The problem is that since USRP2 has a 100 MSample/s sampling and I can't
> just devide it by 12.5 to get the desidered 8 MHz band, I need 
> to use an FPGA decimation of 100 together with an interpolation of 8 in
> order to get the desidered results 
> (I am not using decim 25 and interpol 2, because it is said in the
> specification of USRP2 that both parameters have to be at least 4, and
> multiples of 4, in order to get the full band).
>
> Is this the only way of going about this operation?
>
> Doesn't this eliminate too much usefull information?
>
> Please let me know if you would this in a different way!
> Thank you for your time!
>
> Vlad.
>   
I'm confused.  Interpolation is generally used on Tx, rather than Rx.

What I would do, is specify a decimation of 10, giving you 10MHz of
bandwidth into the
 host, and then filter the result down to 8MHz, and measure that with a
complex-to-mag-squared,
  followed by a single-pole IIR filter.

-- 
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org