I am sure GR can do that, but I can't ;-) Also, I don't have a good waterfall at all of the pocsag broadcast, which is probably part of why I can't make it out with my ears either. Yes, I think I have too much noise. I hope it can be overcome with the right settings and filters.
I'll try to capture a screenshot of what I see. It's nothing like the screenshots in Wikipedia. On Jun 1, 2015 5:47 PM, "Marcus Müller" <marcus.muel...@ettus.com> wrote: > Hi! > I personally think the soundbite from wikipedia is broken, since it's > 11kHz sampling rate violates Nyquist ;) > Well, I must admit that my preferred way of analyzing this wouldn't be the > audible reproduction; if you can see it clearly on the waterfall, and > "optically" have enough dB between the carriers and noise, then you'll be > fine decoding it. > > Now, I trust you're actually seeing excessive noise -- this might point to > problems with your receiver (unsuitable antenna, too much noise in the > amplifier, too little gain, intermodulation). The first step in limiting > noise is always adding appropriate filtering. Can you add a FIR that > selects your POCSAG channel out of your sampling bandwidth? > > Best regards, > Marcus > > On 06/01/2015 11:28 PM, Stephan van Beerschoten wrote: > > You're right in that I need more than GR. The audio of a pocsag broadcast > is very distinct. It's also clearly visible on a waterfall. > The problem is that I have too much static in there. Way too much noise. I > can't get the gqrx module (where I tune and see the waterfall) set right so > the reception is fine. > I think the Wikipedia article had a soundbite of a pocsag encoding. If you > listen to it you'll notice it's very distinct.i just have 90% noise and I > can hear the broadcast in the very background. > On Jun 1, 2015 5:25 PM, "Marcus Müller" <marcus.muel...@ettus.com> wrote: > >> Hi again, >> >> Ok, I'm not familiar with the standard POCSAG, but if you got a signal >> that you still need to decode with something else, how do you know you >> don't get clear reception? What is your measure for "good reception"? >> >> As far as I read the English wikipedia, POCSAC uses a 4.5kHz binary FSK, >> so can you see the two alternating frequency e.g. in a waterfall plot of >> your RX signal? >> Ideally, you'd directly be able to see the 512, 1200 or 2400 baud. >> >> To explain a bit more: >> GNU Radio is not a decoder for any specific standard; think of it as the >> LEGO of SDR. You can build amazing things with it, in fact, there's a lot >> of examples that come with GNU Radio, and useful and complex standard >> implementations (FM receiver, DTV transmission!), but if you need to have >> something that's not there, you might need to a) use someone else's >> Out-Of-Tree module or b) implement that functionality yourself. So I must >> admit that I don't have the slightest idea which settings you're referring >> to :) Maybe you're interested in a quick&dirty introduction to GNU Radio >> [1]. >> >> In the case of POCSAG, I remember gr-pocsag being a thing (search for >> pocsag on cgran.org); I can't remember the original author, and I >> presume it's pretty much dead -- but I'd love to be proven wrong. >> Also, pyboms has pocsag-mrt package, but that seems to rely on GNU Radio >> 3.6.2, if the Readme is correct, so that's pretty dead, too. >> >> >> Best regards, >> Marcus >> >> [1] https://github.com/iZsh/pocsag-mrt >> On 06/01/2015 10:18 PM, Stephan van Beerschoten wrote: >> >> It is. I plan on running the output through a utility that can decode it. >> However, before that can happen I need to find out how I can get a clear >> reception of the broadcast. >> On Jun 1, 2015 4:15 PM, "Marcus Müller" <marcus.muel...@ettus.com> wrote: >> >>> I'm a bit confused, I though POCSAG was a text pager system? >>> >>> On 06/01/2015 10:04 PM, Stephan van Beerschoten wrote: >>> > Hi Guys, >>> > >>> > I compiled gnuradio for my ODROID ARM platform, and I can listen to >>> > regular wideband radio just fine. I am using a Generic RTL2832U with >>> > Rafael Micro R820T tuner. >>> > >>> > The radio quality is fine, and even when using the rtl_fm tool >>> > directly (off topic for this list), it works. >>> > >>> > However, when I switch channels to 155.520 to capture POCSAG >>> > broadcasts I cannot get a clear reception. I can't find any decent >>> > documentation on GR to tell me what each setting is, and I am not a >>> > HAM radio operator so some of the basics evade me. >>> > >>> > I can't get decent POCSAG reception with the rtl_fm tool either, so >>> > this is probably a setting thing somewhere. >>> > >>> > Why can't I get clear reception? Any pointers? >>> > >>> > Stephan >>> > >>> > _______________________________________________ >>> > Discuss-gnuradio mailing list >>> > Discuss-gnuradio@gnu.org >>> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >> >> >
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
