________________________________ From: Bill Stevenson <[email protected]> To: Bill Stevenson <[email protected]> Sent: Wednesday, March 18, 2009 5:16:26 PM Subject: Re: [Discuss-gnuradio] some results about D8PSK (problems) Hello, I have searched the mailing list for the questions about D8PSK and also reviewed the README file for the benchmark_tx.py and benchmark_rx.py, it seemed that D8PSK could not work in a decent way like DQPSK or DBPSK on USRP now. Is that right? I have tried to find out the most appropriate values for --costas-loop and --gain-mu, but still found that 0.05 for the gain of loop filter and 0..001 for the gaim-mu could make the PDR reach 100% with two USRPs seperated with very short distance. Other values for these two arguments would ruin the communication seriously. So the D8PSK could not work well on USRP??? Thanks. Bill ________________________________ From: Bill Stevenson <[email protected]> To: [email protected] Sent: Tuesday, March 17, 2009 4:54:53 PM Subject: [Discuss-gnuradio] some experimentation results about D8PSK (problems) Hi I just did PDR testing between two USRPs with D8PSK modulation scheme.. The files I used are benchmark_rx.py and benchmark_tx.py. Two exceptional results confused me a lot: 1, the --tx-amplitude has to be adjusted to the default value (12000), with which the PDR could reach 100%, otherwise, if 10000 were used, the PDR would experience a huge slump (around 40%). This phenomenon never happened to DQPSK. 2, For indoor testing, the distance between two USRPs should be less than 1 meter. In 1.5 meters, the PDR would also plunge a lot. Is there any problem with the D8PSK in Gnuradio? Should I modify the parameters of the carrier tracking and timing syn circuits? The --costas-loop I used was 0.05 with gain-mu set to 0.001 which worked very well for DQPSK. Thanks! Bill
_______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
