Re: [Discuss-gnuradio] Basic TX RX antennas

[Blair Strang]

Hi,

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
have one.

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
cavalier.

Regards,

    Blair.


On Sun, Nov 23, 2008 at 12:37 AM, ali siddiqi <address@hidden> wrote:
> Hi,
>
> I have got Basic RX and Basic TX daughterboards. But i have no antennas for
> them as they are not provided with these daughterboards by the ettus corp.
> No reference at ettus.com's sales page either.
> While running usrp_wfm_rcv.py, i hear a very faint voice of the fm channel
> when using a 1 foot piece of copper wire.
> How can I get clear signals? Are there any antennas for these
> daughterboards?
>
>
> Secondly, is connecting wire as antenna safe?
> Are there any safety precautions to be taken e.g. using anti static straps?
>
> Thanks
>
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