Re: [Discuss-gnuradio] RFX-400 RF sensitivity

[Marcus Leech]

Greg Troxel wrote:
>  
>
>   Is it possible that
>   the high speed digital signaling on the USRP motherboard is
>   significantly reducing the sensitivity of the daughter-board?
>
> Yes, it is possible.  You should examine the circuit diagram and
> determine what kind of noise floor you would expect, given the NF of
> the first RF amplifier and losses before it; your experiment is not
> enough evidence to conclude that there's any such interference.
>
>
>   
I use a DBS_RX with USRP for radio astronomy.  There are a couple of 
narrowband "birdies"
 created by the overall receiver system.  But I have about 40dB of 
low-noise gain in front of
 the DBS_RX, and I can just about detect somebody farting on the space 
station :-) :-)

For my application, I was worried about noise created by the underlying 
system, but with enough
 low-noise gain "out front", it doesn't seem to matter much.  What 
*does* matter in my application
 is gain stability, which is why I have the USRP+DBS_RX in a 
temperature-controlled environment.