Re: [Discuss-gnuradio] Live fm detection gr-inspector

[CEL]

So, let's really look at what you receive there. What's your antenna? 

When you connect a QT GUI time sink, what's (roundabout) your maximum
amplitude coming out of the USRP Source?

Best regards,
Marcus
On Fri, 2019-06-14 at 23:25 -0500, Daniel Andres Palacios wrote:
> Hello Kyeong, 
> About gain level, it was a desperate measure, in my eagerness to get
> signals. If someone has used managed to detect FM signals and can
> give me the parameters used, 
> I would appreciate it.
> 
> Thanks
> 
> 
> 
> 
> On Thu, Jun 13, 2019 at 10:45 PM Kyeong Su Shin <address@hidden
> > wrote:
> > Hello Daniel,
> > 
> > A few things to note:
> > 
> > -Gain level of USRP B200 does not go up to 120 dB. Sure, GNU Radio
> > or UHD won't complain about this, but it maxes out at around 70 dB
> > (I do not remember the exact number).
> > 
> > -My eyes are untrained (I did study sigint before, but it's been a
> > few years since then), so I cannot tell which peaks are spurious
> > and which peaks are true WBFM signals by simply looking a
> > periodogram. However, it seems like the signal detector block is
> > not detecting some serious (~-40 to -20 dBFS) peaks in the
> > spectrum. If those peaks are FM signals, then the detector block is
> > either misconfigured or is not suitable for the task. If those
> > peaks are not FM signals (are spurious signals or unwanted
> > interferences) and if you are not seeing actual FM signals on your
> > periodogram, then you will need to move your receiver to elsewhere
> > or get a better antenna (and may have to decrease the gain of the
> > receiver).
> > 
> > -gr-inspector's signal detector uses energy detection to detect
> > signals, which works on most types of signals but is also
> > suboptimal (in terms of the detection accuracy). You may want to
> > come up with your own detector block that exploits the
> > characteristics of the FM signal if you want to maximize the
> > detection accuracy (in terms of P_d and P_fa). 
> > 
> > Regards,
> > Kyeong Su Shin
> > 
> > 보낸 사람: Daniel Andres Palacios <address@hidden> 대신 Discuss-
> > gnuradio <discuss-gnuradio-bounces+ksshin=address@hidden>
> > 보낸 날짜: 2019년 6월 14일 금요일 오전 6:14:07
> > 받는 사람: Sebastian Müller
> > 참조: address@hidden
> > 제목: Re: [Discuss-gnuradio] Live fm detection gr-inspector
> >  
> > OK, my bad. 
> > 
> > Here is my actual configuration. But again, signals appear and
> > disappear. 
> > Even when I try to cath a fm station, if the GUI Inspector is not
> > set to manual, a get the same behavior 
> > 
> > Thank you.
> > 
> > 
> > 
> > On Thu, Jun 13, 2019 at 2:11 PM Sebastian Müller <address@hidden>
> > wrote:
> > > I just noticed something else:
> > > The USRP sample rate is set to 500kHz, not 20MHz. So you are only
> > > looking at 2.5 % of the target spectrum! It is also possible,
> > > that
> > > there are just no signals in that particular section.
> > > 
> > > Best,
> > > 
> > > Sebastian Müller
> > > address@hidden
> > > PGP ID DC2AA3EE
> > > 
> > > Am 13. Juni 2019 um 20:20:24, Sebastian Müller (address@hidden)
> > > schrieb:
> > > > Hi Daniel,
> > > >
> > > > from what you tell us, I conclude this is not an issue with gr-
> > > inspector but rather with
> > > > generally receiving signals.
> > > > If you use the QT GUI Sink for instance instead, you will see
> > > the same (empty) spectrum.
> > > > I would recommend to try and get better reception, until you
> > > can distinguish signals
> > > > visually in the spectrum manually. Are you using the correct
> > > antenna for this frequency
> > > > range? Is this antenna positioned in a beneficial location for
> > > reception? Have you played
> > > > around with the Rx gain of the USRP?
> > > >
> > > > Best,
> > > >
> > > > Sebastian Müller
> > > > address@hidden
> > > > PGP ID DC2AA3EE
> > > >
> > > > Am 13. Juni 2019 um 19:10:59, Daniel Andres Palacios (
> > > address@hidden) schrieb:
> > > > > Thanks for your reply
> > > > >
> > > > > I trying to detect and classify all fm transmitted stations
> > > in my country,
> > > > > with the gr-inspector OOT.
> > > > > In my country (Colombia) it goes from 87,9 to 107.9 MHZ.
> > > > > I only have an USRP B200 and think that if I set the center
> > > frequency at 98
> > > > > MHZ and put a bandwidth of 20MHZ its posible to get my goal.
> > > But actually
> > > > > im not getting signals detected
> > > > > [image: Captura de pantalla de 2019-06-13 11-17-05.png]
> > > > >
> > > > > On Tue, Jun 11, 2019 at 12:53 PM Müller, Marcus (CEL)
> > > > > wrote:
> > > > >
> > > > > > Hi Daniel,
> > > > > >
> > > > > > please remember to be specific when asking a question:
> > > "best way" is a
> > > > > > bit ambiguous, and "I'm not getting a good result"
> > > definitely is
> > > > > > insufficient for us to help you make things work better.
> > > What doesn't
> > > > > > work sufficiently well? What happens instead?
> > > > > >
> > > > > > Best regards,
> > > > > > Marcus
> > > > > >
> > > > > > On Tue, 2019-06-11 at 12:36 -0500, Daniel Andres Palacios
> > > wrote:
> > > > > > > Hi to everyone.
> > > > > > >
> > > > > > > What is the best way to receive all fm modifications. I'm
> > > usigin an B200
> > > > > > USRP.
> > > > > > > I think that putting the center frequency at 98M and a
> > > bandwidth of 20M
> > > > > > is a good way,but I'm not getting a good result.
> > > > > > >
> > > > > > > The idea is to detect all fm center frequencies using gr-
> > > inspector
> > > > > > > _______________________________________________
> > > > > > > Discuss-gnuradio mailing list
> > > > > > > address@hidden
> > > > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > > > > >
> > > > >
> > > > >
> > > > > --
> > > > > *Daniel Andrés Palacios Carabalí*
> > > > > *Student of Telemathics engineering*
> > > > > *Icesi University- Cali, Colombia*
> > > > > *===========================*
> > > > > *Estudiante de Ingeniería Telemática*
> > > > > *Universidad Icesi. - Cali, Colombia*
> > > > > _______________________________________________
> > > > > Discuss-gnuradio mailing list
> > > > > address@hidden
> > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > > > >
> > > >
> > > 
> > > _______________________________________________
> > > Discuss-gnuradio mailing list
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> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > 
> > 
> > -- 
> > Daniel Andrés Palacios Carabalí
> > Student of Telemathics engineering
> > Icesi University- Cali, Colombia
> > ===========================
> > Estudiante de Ingeniería Telemática
> > Universidad Icesi. - Cali, Colombia
> 
> 
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