On Wed, May 19, 2010 at 1:48 AM, Josh Blum <j...@joshknows.com> wrote: > You could be running into the issue of frequency offset between the LO's of > the two usrp devices. Try increasing the rate so the symbols are wider > spectrally to make up for the offset. I believe that its the -r option. > > Hope that helps, > -Josh > > On 05/18/2010 06:54 PM, Fisheep wrote: >> >> Hi, >> >> I have currently set up a transmission between USRP1 and USRP2 with >> FLEX900. >> And got the following results. >> >> In gnuradio/gnuradio-example/python/digital/ >> Successful transmission (ok = True) when >> Tx (USRP1) : ./benchmark_tx2.py -f 900M --tx-amplitude=0.4 -m dbpsk2 >> Rx (USRP2) : ./benchmark_rx2.py -f 900M -m dbpsk2 -e eth0 >> Fail (ok = False and lost lots of packets) when >> Tx (USRP2) : ./benchmark_tx2.py -f 900M --tx-amplitude=0.4 -m dbpsk2 -e >> eth0 >> Rx (USRP1) : ./benchmark_rx2.py -f 900M -m dbpsk2 >> >> In addition, if using the original modulation like dbpsk not dbpsk2, the >> transmission also not work as expected. >> >> also ref to the two discussions: >> http://www.ruby-forum.com/topic/203035 >> http://www.ruby-forum.com/topic/202105 >> >> I successfully transmit packet from USRP1 to USRP2 with the following >> parameter setting. >> Tx (USRP1) : benchmark_ofdm_new_tx.py -f 900M --tx-amplitude=0.4 -i 128 >> Rx (USRP2) : benchmakr_ofdm_new_rx.py -f 900M -d 100 >> But the same problem as above, USRP1 can't receive correct packet from >> USRP2. >> >> Does anyone has any suggection about this problem, please let me known, >> Thanks. >> >> Sincerely, >> Fisheep
The LO offset would be my first guess, too. The other issue is that when you specify the bandwidth of the signals, you set the interpolation and decimation rates. The same inter and decim on the USRP1 and USRP2 will produce different bandwidth signals, which won't be able to talk to each other. Tom _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
