Re: [Discuss-gnuradio] Running tunnel.py/benchmark_tx.py (OFDM) with XCVR2450?

[Martin Braun]

On Mon, Jan 30, 2012 at 04:11:05PM +0100, Florian Schlembach wrote:
> We have now extended our tests to the tests with two USRP2s with
> daughterboards: Neither the benchmark_tx.py example nor the tunnel.py is
> receiving any packets. We checked the spectrum and tuned the gains as well.
> (OFDM)
> 
> Now, we played with the benchmark files and tunnel.py located in the 
> narrowband
> folder and therefore changed the modulation scheme from BPSK to GMSK and
> ultimately receiving all the packets!! That's strange.
> 
> Does anybody knows what code be the problem that we can't establish any
> connection using higher order modulation schemes? Could it possibly be our
> slightly outdated UHD version?
> 
> We are totally clueless, so we appreciate any idea/help!

This won't really help, but I remember we had exactly the same troubles here.
This was before UHD was even released, so I doubt that's the reason.
Unfortunately, I can't remember how (or: if) we fixed it :( but I'll
keep you updated if my memory comes up with something.

But fiddling with gain values is often useful; even if you've already
done that I recommend trying again, by reducing tx-amplitude and the
actual gain values, shifting the terminals around (perhaps they're too
close?).

MB

-- 
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

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