The ADC Converters on the USRP and USRP2 are capable of sampling a 32 and 100 mhz spectrum respectively. An USRP with 2 daughterboards can sample up and downlink of GSM900 and the USRP2 can sample GSM1800.
The usb can transport an 8Mhz wide spectrum, which is 4mhz for the downlink and 4mhz for the uplink. In theory you can capture 20 ARFCNs uplink + downlink with 1 USRP if it is possible to detect which of the ARFCNs are transmitting at a given point in time and downconvert only those, leaving out the unused ARFCNs and compressing the spectrum. Given the fact that the GSM900 band is shared between a small number of networks and that the BTS has to leave holes in the spectrum to not interfere with other BTSs a single USRP is at least in theory capable of covering one operator network in the GSM900 band, possibly leaving out the most crowded areas that have more than 160 physical channels transmitting at the same time. So how does this work out in reality? I have only seen an USRP from far away until now. On Sat, Dec 12, 2009 at 08:22:20AM +0330, p q wrote: > > > > > > GSM 900 > > Mobile to BTS (uplink): 890-915 Mhz > > BTS to Mobile(downlink):935-960 Mhz > > Bandwidth : 2* 25 Mhz > > > > GSM 1800 > > Mobile to BTS (uplink): 1710-1785 Mhz > > BTS to Mobile(downlink) 1805-1880 Mhz > > Bandwidth : 2* 75 Mhz > > > > > > > > > > > ---------- Forwarded message ---------- > > From: Karsten Nohl <[email protected]> > > Date: Wed, Dec 9, 2009 at 12:45 PM > > Subject: Re: [A51] USRP2 > > To: p q <[email protected]> > > > > > > why would that be? > > > > On Dec 9, 2009, at 10:03 AM, p q wrote: > > > > even USRP2 is not good for capturing GSM1800 traffic so we are stuck with > >> GSM900 only . is this correct ? > >> _______________________________________________ > >> A51 mailing list > >> [email protected] > >> http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51 > >> > > > > > > > _______________________________________________ > A51 mailing list > [email protected] > http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51 _______________________________________________ A51 mailing list [email protected] http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51
