OK, we'll need a recording of the signal with the stripes, not just a GQRX screenshot, I'm afraid. Could you simply record the complex baseband for maybe 5 to 10 pulsations duration? Preferably also asecond recording from a slightly different TXfrequency, but at the same RX frequency.
Best regards, Marcus On Sat, 2019-12-21 at 23:35 +0300, Геннадий Казачёк wrote: > Hello, thanks for your attention. > > > I always thought these pulsations were due to some kind of bug > with > > Gqrx. If you change the FFT size, the rate of pulsation changes. > No, it doesn't. I've tested, FFT size doesn't affect rate of > pulsation. > > > Also, you don't see this on a real spectrum analyzer, even an > inexpensive one. > I don't have one, but as I said before, decoding is failing when this > pulsations are on the air. So, I believe, that gqrx is fine here. > > > the stripes go away when you turn of the USRPs? > Yes, when I stop graph, this pulsations are gone > > > Also, the stripes aren't there, either, when you use the Lime on > the > > same 1.011 GHz frequency, exactly? > Yes, it is correct, I just disable USRP block, enable Lime block and > swap devices. > > > My suspicion is that this is mostly USB3 emissions > I've tried to connect through USB2, result is the same > > > Also, are you using an external power supply for your USRPs > No, they are connected to my host pc by USB only. > > On Sat, 21 Dec 2019 at 21:15, Ron Economos via USRP-users < > usrp-users@lists.ettus.com> wrote: > > I always thought these pulsations were due to some kind of bug > > with > > Gqrx. If you change the FFT size, the rate of pulsation changes. > > Also, > > you don't see this on a real spectrum analyzer, even an inexpensive > > one. > > > > Ron > > > > On 12/21/19 09:25, Marcus Müller via USRP-users wrote: > > > Just to rule out interferers: > > > > > > * the stripes go away when you turn of the USRPs? > > > * Also, the stripes aren't there, either, when you use the Lime > > on the > > > same 1.011 GHz frequency, exactly? > > > > > > My suspicion is that this is mostly USB3 emissions (those could > > be, but > > > not necessarily are, happening through the USRP itself, or > > through > > > cables, or through your host computer. > > > > > > If your sampling rates allow it (they do, I think you're using > > 500 kHz > > > only¹), try to use a USB2-only cable or port and see whether > > these > > > disappear. > > > > > > Also, are you using an external power supply for your USRPs? If > > this is > > > actually an interferer, it might as well be some periodic > > behaviour of > > > the power supply. > > > > > > Best regards, > > > Marcus > > > > > > > > > ¹That's a sampling rate that should work on B200 and B20xmini, > > but it's > > > uncomfortably low – try with 1 MHz and host-side resampling, > > maybe? > > > > > > On Wed, 2019-12-18 at 21:28 +0300, Геннадий Казачёк via USRP- > > users > > > wrote: > > >> Hello, Sam! > > >> No, I use two devices as transmitter and receiver and third > > board I > > >> use just to observe sonogram. > > >> Pulsations exist on both b205 and b210 devices if I use them as > > a > > >> transmitter and not exist if I use as transmitter another > > vendor's > > >> device - LimeSDR. > > >> > > >> All 3 USRP devices are industrial with metal case, and LimeSDR > > is > > >> not. > > >> > > >> On Wed, 18 Dec 2019 at 21:26, Геннадий Казачёк < > > >> gena.kazac...@gmail.com> wrote: > > >>> All 3 USRP devices are industrial with metal case, and LimeSDR > > is > > >>> not. > > >>> > > >>> On Wed, 18 Dec 2019 at 21:25, Геннадий Казачёк < > > >>> gena.kazac...@gmail.com> wrote: > > >>>> Hello, Sam! > > >>>> No, I use two devices as transmitter and receiver and third > > board > > >>>> I use just to observe sonogram. > > >>>> Pulsations exist on both b205 and b210 devices if I use them > > as a > > >>>> transmitter and not exist if I use as transmitter another > > >>>> vendor's device - LimeSDR. > > >>>> > > >>>> On Wed, 18 Dec 2019 at 18:49, Sam Reiter <sam.rei...@ettus.com > > > > > >>>> wrote: > > >>>>> Just to be clear, you see these pulsations when transmitting > > >>>>> with a b205mini, but not with the b210? > > >>>>> > > >>>>> Is the b205mini a bare board or an industrial model with a > > case > > >>>>> and aluminum heat sync? > > >>>>> > > >>>>> Sam Reiter > > >>>>> Ettus Research > > >>>>> > > >>>>> > > >>>>> On Wed, Dec 11, 2019 at 11:48 PM Геннадий Казачёк via USRP- > > >>>>> users <usrp-users@lists.ettus.com> wrote: > > >>>>>> Hello! > > >>>>>> I'm trying to build QPSK based system on GNURadio. > > >>>>>> I'm using two USRP B205-mini boards as transmitter and > > >>>>>> receiver, also I got B210 board that I run gqrx on to watch > > >>>>>> what is really going on. > > >>>>>> I noticed a strange behaviour on my tests, so I began to > > >>>>>> investigate it and ended to a very simple graph, that is in > > >>>>>> attachment. On a frequencies that are multiple of 10Mhz, > > like > > >>>>>> 1020Mhz all works like expected and sonogram looks good. If > > I > > >>>>>> tune to any other frequency, even 1Hz more or less, the > > >>>>>> sonogram is full of pulsations and frequency of that > > >>>>>> pulsation is depends of exact tune frequency. I attached > > some > > >>>>>> screenshots of that pulsations. > > >>>>>> On receiving part that pulsations cause many errors while > > >>>>>> decoding. > > >>>>>> I got another board, LimeSDR-Mini, and no such behaviour > > >>>>>> observed while running graph on it. > > >>>>>> I wonder what is going on, and how can I fix this problem. > > >>>>>> Thank you. > > >>>>>> _______________________________________________ > > >>>>>> USRP-users mailing list > > >>>>>> USRP-users@lists.ettus.com > > >>>>>> > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > >>>> > > >>>> -- > > >>>> Геннадий Казачёк > > >>> > > >>> -- > > >>> Геннадий Казачёк > > >> > > >> _______________________________________________ > > >> USRP-users mailing list > > >> USRP-users@lists.ettus.com > > >> > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > > > _______________________________________________ > > > USRP-users mailing list > > > USRP-users@lists.ettus.com > > > > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > _______________________________________________ > > USRP-users mailing list > > USRP-users@lists.ettus.com > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
