On Tue, 2010-01-05 at 11:29 +0100, Sylvain Munaut wrote: > so if you place a call in that cell yourself, you can get theses > easily before hand. The only remaining unknowns are the timeslot and > the index. > > Also this will work only if at every point of time there is a > single > active phone > > No, you can eliminate channels that had energy before hand. So you > need a single 'new' phone at a time. But granted it's a little far > fetched and would not be the best method for the usrp because the LO > would take too much time to settle anyway. The USRP can capture 64 MHz of spectrum without changing the LO. The USRP2 can capture 100 Mhz of spectrum without changing the LO. You can change the frequency by changing the DDC in the FPGA, this can be done instantaniously.
The RFX1800 boards are limited to 25 Mhz with the standard baseband filters, but these can be changed. In the standard setup, the RFX boards have two lowpass filters on baseband (one for I, one for Q). If I remember well they are elliptical filters with a cutoff at 12.5 Mhz. So the standard filters give you 2*12.5=25Mhz bandwidth (without changing the LO). If you change these filters, you can go up-to niquist freq. (2*32 MHz for USRP-1 2*50 Mhz for USRP-2) Martin _______________________________________________ A51 mailing list [email protected] http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51
