All right guys, I got it, it works now. The central frequency should have been 1911.795 MHz instead of 1189.5MHz. The final configuration results as follows: [image: imagen.png]
[image: imagen.png] Thank you very much to everybody! Best regards, David El mar, 28 feb 2023 a las 18:17, Marcus Müller (<[email protected]>) escribió: > Hi David, > > please stay in the habit of keeping the mailing list in CC! > > Can you please write this email to the mailing list? > > Thanks, > Marcus > > On 28.02.23 17:55, David Dima wrote: > > Hi Marcus, > > According to Galileo's signal plan > > (https://gssc.esa.int/navipedia/index.php/Galileo_Signal_Plan > > <https://gssc.esa.int/navipedia/index.php/Galileo_Signal_Plan>), E5b > bandwidth is 25MHz, > > but to save memory and resources, I sample at 20MHz because I > demonstrated by testing that > > is enough to process the signal without losing information. > > > > Regarding the Xlating filters: if I tune the USRP in the middle of the > signals (1164MHz + > > (1215-1164)/2)MHz = 1189.5MHz) , then I have to shift the spectrum +- > 15.345 (According to > > Daniel: "The band plan you posted is slightly wrong. The distance > between the > > AltBOC sidebands and the centre frequency is 15 * 1.023 MHz.") to be > able to record at > > 25MHz each band (E5a and E5b). I am trying to do the following: > > imagen.png > > Kind regards, > > David > > > > El mar, 28 feb 2023 a las 17:25, Marcus Müller (<[email protected] > > <mailto:[email protected]>>) escribió: > > > > Hi David, > > > > On 28.02.23 17:17, David Dima wrote: > >> Dear Marcus, all > >> Thank you for your response. You are right, I will try to better > explain the problem: > >> > >> Well, when I record the signals separately (for example E5b) as > shown in the below > >> picture, and after that I try to process the file containing the IQ > samples by means > >> of GNSS-SDR free-tool, I can parse the messages to generate > ephemeris, almanac or > >> Rinex files. Even if E5b bandwidth is 25MHz, it works sampling at > 20 MHz. > >> imagen.png > > > > > > You're losing 1/5 of the relevant spectrum. That doesn't mean it > *can't* work, it's > > just unnecessarily bad – honestly, **why** are you using a sampling > rate that's not > > fit to represent the *full* signal? Can you please state *reasons*? > > > > > >> > >> The issue comes when I try to record both signals at the same time. > Taking into > >> account the suggestions Jim, Daniel and you have given me in the > forum, I have made > >> a couple of changes in the program resulting in: > >> imagen.png > >> Now, at least I think I am closer to getting what I need but I am > not sure if there > >> are more mistakes in the flowgraph. So, I have tried to record the > signals according > >> to the above flowgraph but after that I still cannot read any > signal from the > >> satellites whereas if I record them separately I can. > > > > This makes no sense at all. Where do your "Center Frequencies" in > the Freq.-Xlating > > filters come from? > > > > Best regards, > > Marcus > > >
