Correct me, but this is 400kS/s – that should really not max out anyone's system, unless the spread blocks are really terribly inefficient (I don't think they are); please check this, though!
If I'm not mistaken, gr-spread doesn't tune the hardware or anything – it just creates a continuous phase stream that changes frequency, in a cyclic manner. My guess is that the receiver is frequency-offset from the transmitter, and hence, the demodulator "guesses" the wrong frequencies. Would that be possible? Ajinkya, are you frequency-aligning the two USRPs in any way? Best regards, Marcus On 26.08.2016 21:22, Dave NotTelling wrote: > I have had issues with scheduling transmissions at ~ 10 ms per hop and > ending up with transmissions happening on the wrong frequencies. > Usually it's one channel off. If you slow the system down does > everything work properly? Also, are you pegging out any single core > in your system? I have seen lots of issues with scheduling bursts > when the CPU utilization is high or even a single core that's maxed out. > > On Fri, Aug 26, 2016 at 3:00 PM, Ajinkya D Kadam > <ajinkya.ka...@nyu.edu <mailto:ajinkya.ka...@nyu.edu>> wrote: > > Dave, > > Thanks for replying. > > we are hopping every 80ms. > ᐧ > > On Fri, Aug 26, 2016 at 12:32 PM, Dave NotTelling > <dmp250...@gmail.com <mailto:dmp250...@gmail.com>> wrote: > > Ajinkya, > > How fast are you hopping? I've had loads of issues with > hopping rapidly and not having the correct frequencies used. > > -Dave > > On Tue, Aug 23, 2016 at 7:16 PM, Ajinkya D Kadam > <ajinkya.ka...@nyu.edu <mailto:ajinkya.ka...@nyu.edu>> wrote: > > HI All, > > I am using gr-spread > <https://github.com/CIG-SDR/CIG/tree/master/gr-spread> > module to transmit a signal using FHSS. When I receive the > FHSS signal, the received signal has a completely > different hopping sequence as from the transmitted one. I > am using USRP N210 for transmission and reception. I am > not sure why this is happening. The transmitted sequence > is (frequencies in Khz) > > 187.5 > -12.5 > 162.5 > -62.5 > 62.5 > 137.5 > -112.5 > -37.5 > 112.5 > -162.5 > -137.5 > -87.5 > 12.5 > 37.5 > 87.5 > > and the received sequence is > > 37.5 > 62.5 > 112.5 > -187.5 > 12.5 > 187.5 > -37.5 > 87.5 > 162.5 > -87.5 > 0 > 137.5 > -137.5 > -112.5 > -62.5 > 37.5 > 62.5 > > I have created a movie out of the images which plots the > IQ, FFT and WaterFall plot for the transmitted signal and > the received signal using the "plot_psd_base.py" file in > gr-utils. Please have a look at both of them here > > <https://drive.google.com/file/d/0B-Ksc0hMVyDVLW11QW1BekJtS0E/view> andhere > > <https://drive.google.com/file/d/0B-Ksc0hMVyDVSmU4YzlBVXA5ZFE/view?usp=sharing>. > > > Please see the attached files for the flowgraphs, I am > using as the transmitter and receiver. > > I have stored the received and transmitted signal to a > file. Since these are large files I have uploaded them to > google drive here > > <https://drive.google.com/a/nyu.edu/file/d/0B-Ksc0hMVyDVRTdaVTV5ZmhCVkE/view>. > > > Could someone please help me understand the behavior I am > observing ? > > Is this some sort of synchronization issue ? What am I > missing ? > > Thanks in advance. > > ᐧ > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> > > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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