I just received my USRP today (thanks Ettus!) and am in a similar
position, wanting to smoke test by FM demod.
I probably have more or less the same antenna as you. I cut in half a
1M SMA pigtail I had lying around and soldered 2M of wire out of an
Ethernet cable to the centre conductor. It receives strong FM
stations just fine. I know this antenna is at least some use because
when I unplug it I can’t hear FM stations anymore. Mine is duct-taped
to the ceiling.
First, just to be sure: are you sure your volume is turned up?
I used alsamixer and turned master and PCM right up, then turned up
volume in the app. If the station is just quiet (no
hiss/crackle/noise) then this might be your problem. Or perhaps your
speakers are wimpy and you need headphones.
Second, what can you see in usrp_fft.py (or the wfm app) for the
station you’re trying to recieve? With the basicrx I see a fairly
obvious peak about 25db above noise when tuned to a strong local FM
station. I would also recommend you try the TVRX daughterboard if you
I am obviously new to g-r, and would love to hear what external RF
hardware (antennas? preamps? external radios with IF outputs?)
others are using, regardless of application. I have been lurking in
the list for a while and searched the archives a bit, but there does
not seem to be much discussion of the subject.
Secondly, is connecting wire as antenna safe?
Are there any safety precautions to be taken e.g. using anti static straps?
I think you can get away with it, with a few caveats. Don’t short
anything, get struck by lightning, stick it in a microwave oven, trip
over it, etc. I have been swapping the antenna around with the USRP
powered on. Having now thought about it, I probably shouldn’t be so