u r welcomed! e.g. dst = gr.vector_sink_c () result = dst.data() dump that result into a file using dump(result, the handle of that file). Thanks! Bill ________________________________ From: yufeng wang <kthyuf...@gmail.com> To: Bill Stevenson <bill.stevenso...@yahoo.com> Sent: Friday, April 10, 2009 6:17:49 PM Subject: Re: [Discuss-gnuradio] QPSK phase noise Thanks, Bill. I think we may also use the plot codes under the file gr-utils, where plot_const.py and usrp_fft.py can be found. I have used the usrp_fft.py to display the output signal, and I'm trying to install scipy to enable the plot_const.py, etc. I also wanna load the data using Matlab, I wonder how can you output the data to a sink file? Thanks! On Fri, Apr 10, 2009 at 4:46 PM, Bill Stevenson <bill.stevenso...@yahoo.com> wrote: > Hi, > > We can output the data to a sink file, from which we load the data using > Matlab. Then we use scatterplot. > > Thanks! > > Bill > > ________________________________ > From: yufeng wang <kthyuf...@gmail.com> > To: Bill Stevenson <bill.stevenso...@yahoo.com> > Sent: Friday, April 10, 2009 12:22:15 PM > Subject: Re: [Discuss-gnuradio] QPSK phase noise > > Hi, Bill, > > Regarding to Paco's images, I wonder which programme did you use to > display the output of the images that he had got? like the > constellations? > > I'm using benchmark.py to transmit and receive BPSK signals. I can use > usrp_fft.py to display the output of the transmitter. Thanks in > advance! > > > > On Fri, Apr 10, 2009 at 12:03 PM, Bill Stevenson > <bill.stevenso...@yahoo.com> wrote: >> Hi, Paco >> >> Actually, I got the similar result as you did. I think there was something >> wrong in the mpsk_receiver block. I am checking it. Thanks! >> >> Bill >> >> ________________________________ >> From: Paco Garcia <sarev...@gmail.com> >> To: Discuss-gnuradio@gnu.org >> Sent: Wednesday, April 8, 2009 9:26:36 AM >> Subject: Re: [Discuss-gnuradio] QPSK phase noise >> >> >> Johnathan, you were right with the distortion issue at the TX, I am now >> using >> these parameters: >> >> ./benchma-m dqpsk -f 1.25G -m dqpsk --tx-amplitude=500 -r 1M -M 99999999 >> --excess-bw=0.35 >> ./benchmark_rx.py -r 1M -m dqpsk --log --costas-alpha=0.05 -S 4 --verbose >> -r >> 1M --gain-mu=0.01 --excess-bw=0.35 -f 1.25G --rx-gain=45 >> >> But still, for a 40dB SNR ( >> http://img149.imageshack.us/img149/4583/screenshot4h.png ) I think we >> should >> get a much better constellation than this one ( >> http://img149.imageshack.us/img149/7968/screenshot3t.png ) >> >> I am using the latest gnuradio trunk and the >> ../gnuradio-examples/digital/benchmark.... >> I have disabled all the data loggins but the rx_receiver.dat from the >> /usr/local/lib/python2.5/site-packages/gnuradio/blks2impl/dqpsk.py to >> reduce >> the computational requirements. >> >> I tried the 0.5M as eric suggested but the results are even worse ( >> http://img18.imageshack.us/img18/2306/screenshot5hhm.png ) >> >> The 2M rate constellation is the same as 1M. >> >> If I go with BPSK, I get this: >> http://img212.imageshack.us/img212/3010/screenshot10.png >> using >> ./benchmark_tx.py -m dbpsk -f 1.25G -m dbpsk --tx-amplitude=500 -r 200k -M >> 99999999 --excess-bw=0.35 >> ./benchmark_rx.py -m dbpsk --verbose -S 4 -r 200k --excess-bw=0.35 -f >> 1.25G >> --rx-gain=30 > debug >> >> The image below shows the costas loop error: >> ( http://img156.imageshack.us/img156/1521/screenshot11.png ) >> (zoom frequency > http://img514.imageshack.us/img514/2173/screenshot12.png >> ) >> blue: phase >> red: phase_error >> cian: Q >> purple: I >> green: freq >> >> So once the costas locks, there is still some error which is causing the >> blur constellation. But I think that for an almost 40dB SNR signal ( >> http://img212.imageshack.us/img212/551/screenshot13.png ) we should get >> much >> better results. >> >> The M&M block influences a lot, if I change the samples per symbol to 2 I >> get this: ( http://img201.imageshack.us/img201/9436/screenshot14.png ) >> >> I have also tried via air interface getting similar results. My question >> is >> whether this is normal for the mpsk gnuradio block receiver implementation >> or I am doing something wrong. >> >> What are your thoughts about this? >> >> Thank you for your time. >> >> >> >> >> >> >> >> >> >> >> -- >> View this message in context: >> http://www.nabble.com/QPSK-phase-noise-tp22934944p22950446.html >> Sent from the GnuRadio mailing list archive at Nabble.com. >> >> >> >> _______________________________________________ >> 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 >> >> > > > > -- > Best wishes, > > Yufeng > > -- Best wishes, Yufeng
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