On Mon, May 11, 2015 at 05:24:36PM +0000, Spacefalcon the Outlaw wrote: > I remember DS saying that he has some RF test equipment that could be > used for calibration - DS, perhaps you could give us your thoughts on > whether or not the setup you have could be used to perform calibration > procedures as described above for GSM devices of our own make?
Hi SF, You are absolutely correct, I do have an USRP B100 that I use in tandem with OpenBTS; it works very well, and I can send SMS, place phone calls, and even make IP connections over GPRS. The built-in clock is rather precise, I measured about 300 Hz deviation at 940 MHz using kalibrate, this is almost good enough in theory for GSM which requires 0.5 ppm and 300 / 940e6 = 0.319e-6 = 0.319 ppm, so largely within spec and in theory could be used to calibrate the VCXO. Calibrating rx power level could be a little harder since I lack an absolute power reference, from say an Agilent (Keysight) or some other signal generator; and the USRP does not provide an absolute power ref. However I could use existing calibration values from a working phone as a reference for rx, and possibly tx as well. --DS _______________________________________________ Community mailing list [email protected] https://www.freecalypso.org/mailman/listinfo/community
