Hi, Well, they also have a optional GSM front end board that has an IF. However it has a very narrow IF filter since the goal was to about in-band interference from neighbour channels ... The filters can be set to 28 MHz wide and the LMS has analog I/Q debug outputs, so yes you could get the analog out. But it's I/Q not a single signals so you'll need two fast ADC to get it digitized. OTOH why wouldn't you just use the ADC in the LMS ? They're clocked at 26 Mhz (or could even be fed higher frequency) and so you should be able to get the whole 25 MHz of P-GSM band. Cheers, Sylvain

Albert, In this case yes, it's possible. You could get RXOUT values on the four test points at the north-west corner of the chip (TST5 - TST8). Note, that they are differential and separate I/Q. To acquire 25MHZ you could set LPF to 28MHz, as Sylvain pointed or completely disable it. I strongly recommend you to use an external bandpass filter in the latter case. On Mon, Jun 17, 2013 at 2:08 PM, Albert-Miquel Sánchez &lt;albertm(a)salleurl.edu > Thank you very much for your response. I didn’t mention it, but I only > want to extract the analog signal (the 25 MHz baseband bandwidth), in order > to analyze the spectral content (I would capture this signal with another > board developed by us). Therefore, I don’t need to process it with the > UmTRX. However I need the UmTRX in order to do this analysis while keeping > a phone communication.**** > > ** ** > > Best regards,**** > > ** ** > > Albert**** > > ** ** > > *De:* john.wilson(a)pathintel.com [mailto:john.wilson@pathintel.com] *En > nombre de *John Wilson > *Enviado el:* lunes, 17 de junio de 2013 11:41 > *Para:* Albert-Miquel Sánchez > *CC:* umtrx(a)lists.osmocom.org > *Asunto:* Re: UmTRX**** > > ** ** > > If you need to extract them all simultaneously then you'd need about 25 > MHz baseband bandwidth, which I think at the moment is a bit more than the > UmTRX can do on one channel, you might be able to do something clever and > look across both channels maybe. That's a whole lot of processing as well, > I'm guessing you'll be analyzing the signals offline? USRP2 or USRP N > series and do about 25 MHz sustained on one channel, you'll need some good > network hardware on your PC to prevent overruns.**** > > John**** > > ** ** > > On 17 June 2013 10:23, Albert-Miquel Sánchez &lt;albertm(a)salleurl.edu> **** > > Hello,**** > > I’m an engineer from Spain and I’m interested in a GSM receiver because I > would like to study the internal signals for a research project. In > particular, I’m interested in the analysis of the IF signal, but, as > Alexander told me, the LMS6002D uses zero-IF architecture, so there is no > real "IF" signal, there is only baseband signal. I guess I could also use > this signal for my purposes, but only if all 124 GSM channels can be found > at that point. I’m not sure if this is possible, since there is a low-pass > filter before. Does anybody know if I can extract that information, that > is, the analogic 124 channels after the RF mixer? If it is not possible > with this board, does anybody know if I can do it with another GSM > transceiver board?**** > > Thank you very much in advance.**** > > Best regards,**** > > Albert**** > > > > > -- > *Dr. John Wilson* > Product development engineer, Path Intelligence<http://www.pathintelligence.com/> > T +44 2392 388442 @pathintel > DETECT • ANALYSE • PREDICT • INFLUENCE > > > Path Intelligence Limited, registered number 5176274. Registered in > England, > registered office at 1000 Lakeside North Harbour, Western Road, > Portsmouth, UK, PO6 3EN **** > -- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru