Hi there,
I'm running into clock feedthrough interference at the 5th harmonic of the USRP
oscillator (1088MHz) leaking into the DBSRX board. I found Matt's advice to
Eric Cottrell to change DBSRX C261 and C262 to 4700pF to filter the clock more
aggressively, and while this helped a little, I still have clock noise that
peaks at 40dB above the noise floor (decim. 8, gain 36). Additionally, the
noise is strong enough that I'm picking up intermod at 1084MHz and 1092MHz when
the gain is pushed above 26. Obviously this is reducing my receiver
sensitivity. Two questions:
* Where is the 4MHz modulation coming from that creates intermod at 1084 and
1092?
* How can I reduce clock feedthrough at 1088? Saying "use a different clock
speed" is a perfectly viable answer, though I was hoping for a way to do it
with the stock 64MHz oscillator as it really simplifies things. "Use an LNA" is
another alternative, but since the LNA on the DBSRX is perfectly good it'd
simplify things, again, to use a single amp.
Nick
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