Tuning issues with DBS RX at 900MHz


#1

Hey all

I’ve got a USRP with a DBS RX that I’m trying to tune to an NTSC signal
centered at 909MHz, 6MHz wide (confirmed on a spectrum analyzer). In
order
to get a usable signal out of the usrp for this, I have to turn down to
905MHz, which is outside of where the source is broadcasting (analyzer
shows
this is dead air). Looking at similar signals in this range, I always
have
to tune down 4MHz. I’ve messed with setting lo_offset to different
values
with no changes in my results, tho I havnt found where to pull the
current
lo_offset value from yet (a call to subdev.lo_offset() always yields
0.0).
With the same daughter board, I get different results across the bands.
A
1.2GHz signal I can pick up at 1.2GHz, just as it should be. An NTSC
signal
that should be at 2.4895GHz I need to tune to 2.492 GHz to get a usable
signal. I realize the DBS RX isn’t speced that high, but the signal I’m
getting out of the Flex Rx (Flex 2400 Rx Mimo B) is filled with a bunch
of
high freq noise rendering the signal almost entirely unusable (havnt
gotten
to looking at why that is yet). Any ideas? I believe I’m still running
gnuradio from the revision before gsl was introduced as a dependency.
Perhaps this has been fixed if it actually is a bug. I’m building up the
latest code now and will test to see if everything is magically sane.

Thanks