Hello Mr. Müller, Thanks a lot for the reply! Everything is clear now.
Best regards, Amrit Zoad On Mon, Jun 18, 2018 at 1:21 PM Müller, Marcus (CEL) <muel...@kit.edu> wrote: > Hi Amrit, > > Well, usrp_spectrum_sense is a hopping observer, and GSM is a hopping > system: your probability of intercept is rather low. > > Your probability of intercept is in fact, really zero, if your phone > doesn't do GSM (2G), but uses 3G (UMTS) or 4G (LTE): these use other > frequencies altogether. So, make sure your phone really does do GSM. > > You also don't even have to look at the GSM900 uplink at all: > Telefonica (which Aldi resells) doesn't use that band at all. > > The spectrum sense application is really badly suited for this kind of > task, as it hops: Instead, simply look at the whole band at once. A > simple GNU Radio Companion flow graph connecting the USRP source (samp > rate = total uplink bandwidth) to a Qt GUI Frequency Sink would make > more sense. > > A word of secondary advice: If you're planning to experiment with 2G > networks of your own, or doing something about the basic properties of > microwave propagation and so on, observing spectrum of GSM is a > worthwhile thing to do. Just be warned that it will be increasingly > hard to find GSM signals "in the wild": T-Mobile will switch off GSM > end-of-2020, and thus, up to then, all phones that can do both LTE and > GSM will be instructed to use LTE whenever possible. Since there won't > be much Machine-to-Machine GSM-only (which I assume are the primary > users that won't be able to switch) user equipment in cities, you'll > see that increasingly many phones don't use GSM anymore at all – even > if the network still exists; the calculation is very simple: The amount > of spectrum necessary to let a single user do a GSM phone call is worth > MB/s for a lot of LTE users. Thus, everybody not using GSM is desirable > for network operators. > > Best regards, > Marcus > > On Mon, 2018-06-18 at 11:25 +0200, Amrit Zoad wrote: > > Greetings everyone, > > > > I hope everyone is having a good day. > > > > I have installed GNURadio 3.7 and I wanted to see the GSM signals of my > phone (when I call someone) with the application "USRP Spectrum Scanner > (FFT)". But, I was unable to see any fluctiations in the spectrum from 890 > MHz to 915 MHz & 1710 MHz to 1785 MHz. My location is in Germany and I own > a sim card of Aldi Talk (MEDIONmobile). > > > > Then I tried with my phone's Bluetooth 5.0 and I could see the frequency > hopping from 2.4 GHz to 2.44 GHz along with the light Wi-Fi signals in the > spectrum. > > > > I have the Etttus Research USRP B210 with Bandwidth of 56 MHz (of the > front-end filter) and thus I am setting the sampling rate to 40 MHz. The > antenna also works from 850 MHz to 6.5 GHz. so no problem with that as well. > > > > What could be reason for me not able to see my phone's GSM signals in > the spectrum scanner? > > Your help would be very valuable. > > > > Best regards, > > Amrit Zoad > > +49 177 8474550 <+49%20177%208474550> > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > Discuss-gnuradio@gnu.org > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- Best regards, Amrit Zoad +49 177 8474550
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