On Sep 7, 2008, at 6:58 AM, Michael Ossmann wrote:

On Sun, Sep 07, 2008 at 02:02:35AM +0200, ChoJin wrote:

I tried a very simple test:
- two loops of wire, one for the LFTX (A slot, antenna TXA) and one for
 the LFRX (slot B, antenna RXB)
- generating the sinus wave using usrp_siggen.py -f 0 --sine -w 13.56e6
- trying to detect this sinus back using usrp_fft/usrp_oscope

I put my two loops of wires as close as possible from each other but I
just can't detect my sinus wave back at all.

I think the -w option is outside of your transmit bandwidth.  Try:

# usrp_siggen.py -f 13.5e6 --sine -w 60e3

Also, are you sure that you are receiving on the correct slot and
antenna port?

Thanks, it actually worked,
I had to use -f 13.50 --sine -w 60e3 to get my signal at 13.56Mhz though.

I can now see my signal, but I don't get any sideband channels.
So either my loop of wires is not correct (I actually did it "randomly",
do you have an exact formula for the number of loops vs. diameter?)
or I'll have to really implement the pulses instead of a simple sine signal.

By the way, I'm a little bit confused about the meaning of the antenna slots
on the LF*X boards. Why do we have two slots for the antenna?
I'm currently using the antenna slot A for the LFTX plugged in the slot A and the antenna slot B for the LFRX plugged in the slot B, but I'm not sure
that's what I was supposed to do.

--
Best Regards,
ChoJin


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