On Mon, 2009-06-29 at 19:43 +1000, Nick Withers wrote: > 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).
I've attached an image of a plot of the in-phase samples received from my wind profiler code... It may well be horribly misleading, given that it's highly pre-alpha stuff, but it might also give someone a clue. Certainly looks bizarre to me! Looks like a mix of the real and quadrature samples I want / am expecting to see (~10 kHz wave; we're sampling over 0.2 ms), along with their sum(?) and some zeroes thrown in for good measure. But yeah, this may not actually be as a result of the same problem, but more my in-development work. > (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: n...@nickwithers.com Web: http://www.nickwithers.com Mobile: +61 414 397 446
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