[Discuss-gnuradio] USRP - No quadrature samples

[Nick Withers]

G'day everyone,

I'm a bit worried... I no longer seem to be able to get anything but
zeroes on the quadrature channel out of gr-radar-mono (and my derived
wind profiler code).

(Warning: This is pretty much all FPGA-side code)
____

Short version: I seem to be getting only zeroes for quadrature samples.
Could this be a software problem? Have I mucked up my hardware?

I'm using a USRP rev. 4 with a BasicRX. GNUradio 3.2, Ubuntu 9.04.
____

I get quadrature "samples" as expected if I run with debugging ("-D"
flag to usrp_radar_mono), which chucks through FPGA-generated data. If I
modify my wind profiler code to throw quadrature samples to both the
real and imaginary output channels, I get nothin' but zeroes on both
real and imaginary.

I'm examining data by using read_complex_binary
(gnuradio-core/src/utils/read_complex_binary.m) and plotting with
"plot(real(samples))" / "plot(imag(samples))" in GNU Octave.

It's taken me a while to notice this problem and a couple of things have
happened lately that may be related:
  - I've physically moved my USRP / PC / signal generator; and
  - I've updated over a hundred packages on the Ubuntu 9.04 PC to bring
it up to date.

Could this be a software issue? From looking at synaptic it did look
like I had registered GNUradio / USRP packages (libgnuradio, libusrp,
etc.), which I imagine I had installed yonks ago before I'd built
GNUradio from SVN. I've tried removing all those and rebuilding GNUradio
3.2 from scratch, but the problem persists. I can rebuild the box, but
if it's just gonna reinstall the same required libraries and so forth
that I may be having a problem with it may not give me very helpful. I
can rebuild the box with another OS but I'm trying to stay as boring and
mainstream as possible.

...Or maybe I've stuffed my USRP hardware? I'm working almost
exclusively in the FPGA...

If someone with an up-to-date Ubuntu 9.04 machine with GNUradio 3.2
could try to reproduce this I'd owe them a beer!

Any pointers appreciated, cheers all!
-- 
Nick Withers
email: address@hidden
Web: http://www.nickwithers.com
Mobile: +61 414 397 446

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