Dear Ed Troy: Update: I was able to reproduce (..or maybe create a similar) problem on an another computer; the problem was mainly due to buffer underrun (may have to do with the data rate of the PlutoSDR source) . The two-clock problem may also exist (but is not tested). There should be a better fix, but as a quick & dirty fix, I just added a few delay blocks to the flowgraph and it worked on that computer as well.
The flowgraph is attached. (Again, it is not a proper fix. Maybe you want to look at better implementations, such as gqrx, or find more appropriate ways to adjust the buffer..) Regards, Kyeong Su Shin On Mon, Dec 18, 2017 at 1:41 AM, Kyeong Su Shin <kss...@uw.edu> wrote: > Dear Ed Troy: > > (Also, it is not a simple flowgraph, but I heard that there is a test > build of GQRX for PlutoSDR (gr-iio based). You should be able to use that > to demodulate WBFM signals, if that is all you want..) > > Regards, > Kyeong Su Shin > > On Mon, Dec 18, 2017 at 1:34 AM, Kyeong Su Shin <kss...@uw.edu> wrote: > >> Dear Ed Troy: >> >> Actually, I did re-test this with a PlutoSDR (I do have one unit at home, >> although I do not usually carry this with me) and your flowgraph worked on >> my PC + PlutoSDR once I reduced the sampling rate from 5MS/s to 2.5MS/s >> (and adjusted the decim ratio accordingly). Could you try different FM >> stations, different antennas, or different GNU Radio installations (maybe >> try running this on different computers)? >> >> One other thing that I would check is the sampling rate that the audio >> card supports. I know 96kS/s is usually an acceptable value (and did work >> on my PC), but maybe you should try 48kS/s instead. >> >> I am also concerned about the two-clock problem between the PC and the >> radio, but I still expect to get some audible sounds even in the worst case >> scenario... >> >> Regards, >> Kyeong Su Shin >> >> On Sun, Dec 17, 2017 at 9:08 AM, Ed Troy <et...@aeroconsult.com> wrote: >> >>> Hi Kyeong, >>> First, sorry about the double transmission of my message. I did not >>> attach [discuss-gnuradio] to the first one and when I did not see it, I >>> figured it got lost and so resent with the correct subject line. >>> >>> I have checked my board and it does seem to work down to 90 MHz. I need >>> to run more detailed tests with a signal generator to get exact sensitivity >>> numbers, but it should be good enough. >>> >>> I tried making the changes to sample rate and other things that you >>> suggested, but it still does not demodulate FM broadcast signals. I have to >>> admit that the RTL-SDR devices never did a very good job, either, but I >>> attributed that to relatively poor sensitivity, although I have some pretty >>> good ones, as far as they go. I also tried to lower the gain, but that did >>> not seem to work, either. >>> >>> If anyone has had success getting the Pluto to work with FM broadcast >>> signals, perhaps they could publish the grc file? >>> Regards, >>> Ed >>> >>> >>> >>> On 12/15/2017 8:33 PM, Kyeong Su Shin wrote: >>> >>> Dear Ed Troy: >>> >>> I don't have the PlutoSDR with me right now, so I cannot test it now, >>> but a few things to check: >>> >>> -Make sure that your Pluto can go down to 90MHz alright; it is only >>> rated to operate on 325MHz - 3.8GHz, and not guaranteed to behave well on >>> such frequencies (even when you did made the changes). >>> -Try lower sampling rate; like 2MS/s. PlutoSDR is known to drop samples >>> at relatively high sampling rates (and yes, I do mean that 5MS/s is too >>> high). >>> -Try lowering gain; FM signals can easily overload the frontend of such >>> devices. >>> >>> If I replace that PlutoSDR source block with an Osmocom source block, >>> change the carrier frequency to my local station, and attach a different >>> radio, it works. (Can't test on a PlutoSDR now, as I do not have one with >>> me now). >>> >>> Regards, >>> Kyeong Su Shin >>> >>> On Fri, Dec 15, 2017 at 4:12 PM, Ed Troy <et...@aeroconsult.com> wrote: >>> >>>> Hi, >>>> >>>> I have been trying to get my Pluto to work with WBFM, but I am not >>>> having any luck. I am attaching a grc file that I am pretty sure should >>>> work, but it does not. It just generates sporadic noise. I did the changes >>>> recommended to get the Pluto to work over a wider frequency range, and the >>>> results indicated that the changes worked. And, I have tried using the >>>> Pluto at higher frequencies to detect a WBFM signal, and it still does not >>>> work properly. So, I know it has to be something with my grc file. >>>> >>>> What am I doing wrong? >>>> >>>> Ed >>>> >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> >>> -- >>> RF, Microwave, Antenna, and Analog Design, >>> Development,Simulation, and Research Consultinghttp://aeroconsult.com >>> Aerospace Consulting LLC >>> P.O. Box 536 >>> Buckingham, Pa. 18912(215) 345-7184(215) 345-1309 FAX >>> >>> >> >
wbfm_receiver_ksshin.grc
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