Re: [Discuss-gnuradio] sampling artefact because of two step mixing?

[Don Ward]

I have observed a similar phenomenon with the LFRX daughterboard.  It seems 
there is often (or always?) a peak at DC in the baseband (USRP output) 
spectrum, regardless of the tuned frequency of the USRP.  I suspect it is 
due to rounding down in the CIC decimation filter.  Adding a value of 
e*complex(1.0,1.0) where 0.5 <= e <= 0.8 to the USRP output will cancel it.

-- Don W.

----- Original Message ----- 
From: "Luis Simoes" <address@hidden>
[snipped]
> As I feed the USRP with a single sine tone with a frequency of 2.444 GHz 
> and
> an amplitude of -50dbm I saw on my plot a nice peak at 2.444 GHZ but also 
> a
> second peak at 2.452 GHZ but attenuated by 15 db's when daughter board is
> tuned to 2.452 Ghz.