Re: [Discuss-gnuradio] some results about D8PSK (problems)

[Bill Stevenson]

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From: Bill Stevenson <address@hidden>
To: Bill Stevenson <address@hidden>
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 

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From: Bill Stevenson <address@hidden>
To: address@hidden
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