On Tue, 24 Apr 2012 07:52:09 -0700, Nick Foster wrote: > On Tue, Apr 24, 2012 at 5:13 AM, Alick Zhao <alick9...@gmail.com> wrote: > >> Hi list, >> >> I am experimenting with narrowband benchmark_tx/rx in real indoor air >> interface. The software is GNU Radio 3.5.3.2 and the hardware available >> is USRP with RFX2400 daughter boards. >> >> When I use gmsk modulation to transmit and receive, the performance is >> quite good - very few packets are lost or received wrongly. However, >> with dbpsk, I find the performance is quite degraded. I have not seen >> better results than the case with (ok, rx, total) is about (407, 470, >> 666), which means no more than 2/3 of the packets can be received. >> Besides, I got some OOO in the receiver side and this tell me overrun >> happens. This is also not the case with gmsk. The current bitrate is >> 125kHz and samples per symbol is set to 2, and I find this results in >> the lowest sample rate for USRP. So it is impossible to lower down the >> sample rate :( >> >> Is the performance degradation with psk normal? Does anyone experience >> the same issue? Can it be improved in some way? One labmate told me that >> he once worked with GNU Radio 3.2 and the same hardware but he didn't >> see such performance with psk. So is the new UHD interface/driver >> related? >> > > Alick, > > You will have to instrument your flowgraph in order to find out. Add file > sinks to different stages in the transmitter and receiver to verify that > the data looks as expected. You can use MATLAB or Octave to visualize the > data. There are scripts in gnuradio-core/src/utils which will aid you in > loading sample data into MATLAB. Verify that the frequency offset is within > bounds and being handled appropriately. Verify that clock recovery is > keeping a lock on the incoming data. > > --n
Thanks Nick for your guidance, but I am not sure how much offset in freq/timing is within bounds. Could you give some empirical value or something? I now add some code into benchmark_rx.py to make it output freq offset, timing offset just as digital_bert_rx.py does. Here is a snip of the output of one run with tx freq 2.4400065G, rx freq 2.44G, dbpsk mod/demod, two USRPs ~3m apart. (I attach the full log if it helps.) H: 0.17e(j6.39deg) Freq. Offset: 82 Hz Timing Offset: 26936.2 ppm H: 0.20e(j-15.52deg) Freq. Offset: 56 Hz Timing Offset: 32088.3 ppm H: 0.21e(j-73.59deg) Freq. Offset: 108 Hz Timing Offset: -12522.0 ppm H: 0.22e(j62.82deg) Freq. Offset: 117 Hz Timing Offset: -57538.1 ppm H: 0.22e(j62.82deg) Freq. Offset: -18 Hz Timing Offset: -24022.2 ppm H: 0.22e(j-41.16deg) Freq. Offset: -289 Hz Timing Offset: 28046.4 ppm H: 0.14e(j44.06deg) Freq. Offset: -278 Hz Timing Offset: 62429.5 ppm H: 0.14e(j44.06deg) Freq. Offset: -52 Hz Timing Offset: 6915.0 ppm H: 0.20e(j-15.17deg) Freq. Offset: -23 Hz Timing Offset: -11427.6 ppm You can see that the freq offsets are mostly less than some hundred Hz, and timing offsets are mostly at 10^5 ppm. Also the signs of offsets look random. Is this OK or not? The packet number of (ok, rx, total) is (230, 338, 666) in this run. PS: The H is the estimated channel (I hope it will be). It won't make sense if the freq/timing is not locked. alick
H: 5.00e(j0.00deg) Freq. Offset: 0 Hz Timing Offset: 0.0 ppm H: 0.17e(j6.39deg) Freq. Offset: 82 Hz Timing Offset: 26936.2 ppm H: 0.20e(j-15.52deg) Freq. Offset: 56 Hz Timing Offset: 32088.3 ppm H: 0.21e(j-73.59deg) Freq. Offset: 108 Hz Timing Offset: -12522.0 ppm H: 0.22e(j62.82deg) Freq. Offset: 117 Hz Timing Offset: -57538.1 ppm H: 0.22e(j62.82deg) Freq. Offset: -18 Hz Timing Offset: -24022.2 ppm H: 0.22e(j-41.16deg) Freq. Offset: -289 Hz Timing Offset: 28046.4 ppm H: 0.14e(j44.06deg) Freq. Offset: -278 Hz Timing Offset: 62429.5 ppm H: 0.14e(j44.06deg) Freq. Offset: -52 Hz Timing Offset: 6915.0 ppm H: 0.20e(j-15.17deg) Freq. Offset: -23 Hz Timing Offset: -11427.6 ppm H: 0.20e(j-15.17deg) Freq. Offset: 55 Hz Timing Offset: 25745.7 ppm H: 0.20e(j-15.17deg) Freq. Offset: 55 Hz Timing Offset: 25745.7 ppm H: 0.20e(j-15.17deg) Freq. Offset: 55 Hz Timing Offset: 25745.7 ppm H: 0.20e(j-15.17deg) Freq. Offset: -53 Hz Timing Offset: -34341.6 ppm H: 0.17e(j60.63deg) Freq. Offset: 4 Hz Timing Offset: 15150.0 ppm H: 0.22e(j-40.98deg) Freq. Offset: -76 Hz Timing Offset: 19942.9 ppm H: 0.16e(j-58.36deg) Freq. Offset: 148 Hz Timing Offset: -22461.8 ppm H: 0.24e(j-72.84deg) Freq. Offset: -123 Hz Timing Offset: 629207.6 ppm H: 0.20e(j22.13deg) Freq. Offset: -278 Hz Timing Offset: 1137018.1 ppm H: 0.16e(j36.69deg) Freq. Offset: 68 Hz Timing Offset: 12676.7 ppm H: 0.22e(j-52.58deg) Freq. Offset: -41 Hz Timing Offset: 41515.9 ppm H: 0.16e(j-37.89deg) Freq. Offset: 54 Hz Timing Offset: -23489.6 ppm H: 0.22e(j50.68deg) Freq. Offset: 152 Hz Timing Offset: -10888.1 ppm H: 0.20e(j-15.53deg) Freq. Offset: -303 Hz Timing Offset: -33853.4 ppm H: 0.21e(j-51.42deg) Freq. Offset: -8 Hz Timing Offset: 20347.4 ppm H: 0.15e(j2.83deg) Freq. Offset: -89 Hz Timing Offset: -29398.9 ppm H: 0.18e(j32.48deg) Freq. Offset: 127 Hz Timing Offset: -25175.3 ppm H: 0.19e(j68.17deg) Freq. Offset: 150 Hz Timing Offset: 9722.2 ppm H: 0.17e(j-3.72deg) Freq. Offset: -39 Hz Timing Offset: -22859.7 ppm H: 0.16e(j-25.93deg) Freq. Offset: 45 Hz Timing Offset: 3825.1 ppm H: 0.17e(j70.81deg) Freq. Offset: 183 Hz Timing Offset: 18049.7 ppm H: 0.17e(j70.81deg) Freq. Offset: 119 Hz Timing Offset: -25533.8 ppm H: 0.21e(j-43.82deg) Freq. Offset: 116 Hz Timing Offset: -22652.5 ppm H: 0.21e(j-43.82deg) Freq. Offset: 64 Hz Timing Offset: 52012.5 ppm H: 0.21e(j-43.82deg) Freq. Offset: 11 Hz Timing Offset: 10960.9 ppm H: 0.21e(j-43.82deg) Freq. Offset: 11 Hz Timing Offset: 10960.9 ppm H: 0.13e(j-10.93deg) Freq. Offset: -257 Hz Timing Offset: 50109.7 ppm H: 0.23e(j31.29deg) Freq. Offset: -281 Hz Timing Offset: 242820.4 ppm H: 0.22e(j-56.39deg) Freq. Offset: 134 Hz Timing Offset: -10706.7 ppm H: 0.21e(j2.66deg) Freq. Offset: -80 Hz Timing Offset: 1186205.6 ppm H: 0.19e(j-27.09deg) Freq. Offset: -333 Hz Timing Offset: -10812.3 ppm H: 0.19e(j-27.09deg) Freq. Offset: 226 Hz Timing Offset: 8761.8 ppm H: 0.19e(j-27.09deg) Freq. Offset: 130 Hz Timing Offset: -35554.3 ppm H: 0.19e(j-27.09deg) Freq. Offset: 130 Hz Timing Offset: -35554.3 ppm H: 0.25e(j-27.76deg) Freq. Offset: -77 Hz Timing Offset: 484285.3 ppm H: 0.18e(j-41.36deg) Freq. Offset: 118 Hz Timing Offset: 1260950.4 ppm H: 0.19e(j-53.25deg) Freq. Offset: -580 Hz Timing Offset: 1476557.5 ppm H: 0.19e(j-53.25deg) Freq. Offset: -580 Hz Timing Offset: 1476557.5 ppm H: 0.19e(j-53.25deg) Freq. Offset: -580 Hz Timing Offset: 1476557.5 ppm H: 0.19e(j-53.25deg) Freq. Offset: -580 Hz Timing Offset: 1476557.5 ppm H: 0.19e(j-53.25deg) Freq. Offset: -580 Hz Timing Offset: 1476557.5 ppm H: 0.19e(j-53.25deg) Freq. Offset: 48 Hz Timing Offset: 1198590.6 ppm H: 0.06e(j-61.35deg) Freq. Offset: -129 Hz Timing Offset: 78212.8 ppm H: 0.23e(j-15.67deg) Freq. Offset: -195 Hz Timing Offset: 13075.0 ppm H: 0.21e(j39.62deg) Freq. Offset: -211 Hz Timing Offset: 35391.3 ppm H: 0.23e(j-53.32deg) Freq. Offset: -16 Hz Timing Offset: -15506.1 ppm H: 0.23e(j19.85deg) Freq. Offset: -79 Hz Timing Offset: 5644.3 ppm H: 0.23e(j-75.68deg) Freq. Offset: 246 Hz Timing Offset: 102468.2 ppm H: 0.21e(j-36.48deg) Freq. Offset: -143 Hz Timing Offset: 19947.2 ppm H: 0.23e(j15.56deg) Freq. Offset: -105 Hz Timing Offset: -19816.2 ppm H: 0.20e(j40.33deg) Freq. Offset: 114 Hz Timing Offset: -45366.4 ppm H: 0.22e(j-0.98deg) Freq. Offset: 124 Hz Timing Offset: 11477.3 ppm H: 0.07e(j-53.69deg) Freq. Offset: 87 Hz Timing Offset: 25982.7 ppm H: 0.23e(j48.52deg) Freq. Offset: -108 Hz Timing Offset: -21126.6 ppm H: 0.20e(j-46.17deg) Freq. Offset: 34 Hz Timing Offset: 48765.1 ppm H: 0.20e(j-45.49deg) Freq. Offset: -200 Hz Timing Offset: -19929.6 ppm H: 0.20e(j-45.49deg) Freq. Offset: 223 Hz Timing Offset: -17855.9 ppm H: 0.22e(j36.50deg) Freq. Offset: -3 Hz Timing Offset: 11067.9 ppm H: 0.15e(j56.54deg) Freq. Offset: -15 Hz Timing Offset: 55332.1 ppm H: 0.15e(j56.54deg) Freq. Offset: -99 Hz Timing Offset: 11031.1 ppm H: 0.22e(j-34.42deg) Freq. Offset: -141 Hz Timing Offset: -18745.9 ppm H: 0.21e(j-27.65deg) Freq. Offset: -150 Hz Timing Offset: -31276.0 ppm H: 0.25e(j18.81deg) Freq. Offset: -182 Hz Timing Offset: -20511.7 ppm H: 0.21e(j65.20deg) Freq. Offset: -52 Hz Timing Offset: -1532.1 ppm H: 0.17e(j67.18deg) Freq. Offset: 216 Hz Timing Offset: 701350.3 ppm H: 0.04e(j-61.12deg) Freq. Offset: -8 Hz Timing Offset: 1063452.6 ppm H: 0.15e(j-49.22deg) Freq. Offset: 131 Hz Timing Offset: 31760.0 ppm H: 0.17e(j9.56deg) Freq. Offset: -332 Hz Timing Offset: -35488.1 ppm H: 0.19e(j-16.75deg) Freq. Offset: -298 Hz Timing Offset: 21904.9 ppm H: 0.18e(j34.09deg) Freq. Offset: -536 Hz Timing Offset: 9304.0 ppm H: 0.18e(j34.09deg) Freq. Offset: -1 Hz Timing Offset: 38027.9 ppm H: 0.18e(j34.09deg) Freq. Offset: -47 Hz Timing Offset: -32457.7 ppm H: 0.19e(j39.81deg) Freq. Offset: 177 Hz Timing Offset: 11485.4 ppm H: 0.20e(j12.35deg) Freq. Offset: -87 Hz Timing Offset: 923909.5 ppm H: 0.20e(j-49.26deg) Freq. Offset: -132 Hz Timing Offset: 1379974.1 ppm H: 0.20e(j-49.26deg) Freq. Offset: -192 Hz Timing Offset: 13427.0 ppm H: 0.20e(j-49.26deg) Freq. Offset: -40 Hz Timing Offset: 11120.0 ppm H: 0.21e(j-70.65deg) Freq. Offset: 7 Hz Timing Offset: -16541.9 ppm H: 0.24e(j-17.39deg) Freq. Offset: -9 Hz Timing Offset: -26569.2 ppm H: 0.21e(j-46.03deg) Freq. Offset: -271 Hz Timing Offset: -8623.8 ppm H: 0.21e(j-3.00deg) Freq. Offset: 29 Hz Timing Offset: 365.6 ppm H: 0.21e(j71.87deg) Freq. Offset: 7 Hz Timing Offset: -17362.8 ppm H: 0.19e(j-17.58deg) Freq. Offset: -284 Hz Timing Offset: -1721.7 ppm H: 0.14e(j71.10deg) Freq. Offset: -180 Hz Timing Offset: 38639.5 ppm H: 0.23e(j-7.26deg) Freq. Offset: 230 Hz Timing Offset: 236689.0 ppm H: 0.23e(j-7.26deg) Freq. Offset: -17 Hz Timing Offset: -3839.5 ppm H: 0.16e(j-46.25deg) Freq. Offset: -261 Hz Timing Offset: -43686.8 ppm H: 0.16e(j-46.25deg) Freq. Offset: -261 Hz Timing Offset: -43686.8 ppm H: 0.19e(j-73.93deg) Freq. Offset: -595 Hz Timing Offset: 46389.4 ppm H: 0.21e(j-44.19deg) Freq. Offset: -26 Hz Timing Offset: -11491.6 ppm H: 0.22e(j4.26deg) Freq. Offset: -118 Hz Timing Offset: 22056.9 ppm H: 0.22e(j-64.60deg) Freq. Offset: -92 Hz Timing Offset: -6711.0 ppm H: 0.22e(j-64.60deg) Freq. Offset: -102 Hz Timing Offset: -2989.0 ppm H: 0.22e(j-64.60deg) Freq. Offset: -236 Hz Timing Offset: 33092.2 ppm H: 0.16e(j-22.23deg) Freq. Offset: -65 Hz Timing Offset: 37522.1 ppm H: 0.22e(j12.61deg) Freq. Offset: -182 Hz Timing Offset: -18559.1 ppm H: 0.24e(j-48.10deg) Freq. Offset: -62 Hz Timing Offset: 28855.4 ppm H: 0.24e(j-48.10deg) Freq. Offset: -315 Hz Timing Offset: 13965.0 ppm H: 0.24e(j-48.10deg) Freq. Offset: -386 Hz Timing Offset: -33329.9 ppm H: 0.24e(j-48.10deg) Freq. Offset: -143 Hz Timing Offset: -30086.7 ppm H: 0.24e(j-48.10deg) Freq. Offset: 53 Hz Timing Offset: -26000.7 ppm H: 0.24e(j38.22deg) Freq. Offset: -144 Hz Timing Offset: 2619.7 ppm H: 0.20e(j10.61deg) Freq. Offset: -718 Hz Timing Offset: 25939.7 ppm H: 0.17e(j-72.88deg) Freq. Offset: -451 Hz Timing Offset: -7320.2 ppm H: 0.17e(j-26.40deg) Freq. Offset: -481 Hz Timing Offset: -31214.7 ppm H: 0.20e(j-29.62deg) Freq. Offset: -428 Hz Timing Offset: -21284.1 ppm H: 0.23e(j-19.79deg) Freq. Offset: -539 Hz Timing Offset: 11943.4 ppm H: 0.21e(j-54.40deg) Freq. Offset: -108 Hz Timing Offset: -30892.7 ppm H: 0.21e(j-54.40deg) Freq. Offset: 630 Hz Timing Offset: 22772.0 ppm H: 0.21e(j-54.40deg) Freq. Offset: 3336 Hz Timing Offset: 44976.2 ppm H: 0.21e(j-54.40deg) Freq. Offset: 3025 Hz Timing Offset: -80895.4 ppm H: 0.21e(j-54.40deg) Freq. Offset: 4563 Hz Timing Offset: 2358.1 ppm H: 0.21e(j-54.40deg) Freq. Offset: -695 Hz Timing Offset: -422993.4 ppm H: 0.21e(j-54.40deg) Freq. Offset: 243 Hz Timing Offset: -463919.4 ppm H: 0.21e(j-54.40deg) Freq. Offset: -4461 Hz Timing Offset: -257269.8 ppm H: 0.21e(j-54.40deg) Freq. Offset: -275 Hz Timing Offset: -200737.0 ppm
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