On Fri, Apr 13, 2012 at 4:47 AM, ηδΌε <wangzichen...@gmail.com> wrote:
> Hi everyone, > I want to realize a BPSK modulation by using GRC to transmit some bytes of > information. Simulation result under a pure software environment performs > good. However, when I move to hardware step with two USRPs connected with > cable and 6dB attenuator(a simplex scenario), less than half of the > transmitted bytes can be received. I think may be a synchronization problem > occurs. Then I decide to do a loopback setting (flow graph is attached and > please check it) with one USRP N210. This time, again, I cannot receive all > the the transmitted strings. Detailed information are shown below: > Ubuntu 10.04, GNU Radio software version 3.5.2.1, 2 samples/symbol, sample > rate 195.312K, both Gray coding and Differential encoding are turned on, > excess bandwidth 0.35, realtime scheduling, transmitted strings 468Bytes, > UHD gain 0dB, payload length 1(nothing received when payload length equals > 0) and central frequency at 1GHz. > Rx bytes: 82; 78; 79; 68; 51; (All 5 times shows very bad results, so I > adjust some parameters) > I turn off the Gray coding, keep the Differential encoding on; increase > samples/symbol to 5(5 samples/symbol gives the best receiving result); > Rx bytes: 418; 421; 417; 405; 415; Still I cannot receive all transmitted > bytes.I think synchronization is provided by packet encoder already. What > could be the possible reasons? I also try the 'run to completion' option > but nothing received. Why random results appear? I am sure the cable and > Ethernet cable have no problem. > Thanks a lot! > Kind Regards! > Wei > Try a payload length longer than 1. In addition, please use an attenuator of at least 20dB -- using only 6dB between the TX and RX will still provide enough energy to damage your daughterboard if you turn the gains up. --n _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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