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.
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