Re: [Discuss-gnuradio] running OFDM on USRP2

[Tom Rondeau]

On Wed, Jan 27, 2010 at 11:21 AM, bin zan <address@hidden> wrote:
> Hello,
>        I was trying to run following OFDM command on USRP2, however, I got a
> bunch of "SSSSStime out" at the receiver side.
>
> ./benchmark_ofdm_tx.py -f 2.4G -i 512 --fft-length=64 --occupied-tones=32
> --cp-length=4
> ./benchmark_ofdm_rx.py -f 2.4G -d 256 --fft-length=64 --occupied-tones=32
> --cp-length=4
>
> I wonder if there is any one successfully running OFDM on USRP2, what are
> the command parameters you are using and if there is any modification in the
> code, can you let me know.
>
> Thanks,
> Bin


The 'S' appear because you're missing packets. Using the interpolation
and decimation rates you specified shouldn't be taxi/ng your CPU,
which is a common cause of these problems. Are you running the USRP2
through a switch or is it directly connected?

The "time out" occurs when the receiver sees the preamble symbol of
the OFDM stream but nothing else. So what is probably happening is
that you get some of the symbols through, including the preamble
symbol, but you're dropping other packets (causing the Ses), which
will trigger the "time out" message.

Tom