On Mon, 2011-01-10 at 15:55 -0500, Thomas H Kim wrote: > All, > > I am testing 2x USRP1 with RFX2400 daughter cards with benchmark_rx > and benchmark_tx scripts and have questions. > When I set the MCS to dbpsk, error rate I got was close to zero. > When I set it to dqpsk, d8psk, error rate is 100%. > When I set it to gmsk, certain daughter cards had close to 0 error > rate, but certain swung from 0% to 100%. > > I asked about it to Ettus research, they told me that it's likely to > be due to frequency offset between the two boxes I have. > If it is true, > 1) how can I compensate the offset?
Make a simple little FFT sink in GRC and use it on one of the USRPs to determine the received signal offset from the other USRP while it is transmitting. Or receive a signal from a signal generator of known frequency and note the offset for both USRPs. Or transmit a signal from each USRP and receive it using a different receiver and note the difference between the frequencies of the received signals. Or vary the frequency of either benchmark_rx or benchmark_tx via trial and error until you get proper transmission/reception. You will probably find less than 20kHz of offset at 2.4GHz. --n > 2) Has someone used dqpsk, d8psk in 2.4MHz ISM band before? If so, > what extra step is necessary? > Thanks, > > Thomas > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
