Matt, thanks for your reply.
> >Using a noise generator, I came up with the following figures: > > > >USRP settings: DBSRX, gain 52, decimation factor 32 > >Calibration bandwidth: 190 kHz around center frequency, 3dBm cable loss > >accounted for > > > > That's a lot of cable loss. Are you sure its that much? The figure I posted was wrong, it was actually 1.3 dB. > >I noticed that (with gain 52) the USRP goes into saturation above -50 > >dBm and does not quite show linear behaviour below -100 dBm. > > > Not sure what you mean above. With gain of 52, the system gain is > pretty high. For a strong signal like -50dBm you would want to have a > lower gain. I was trying to measure signals starting at roughly -100 dBm (400kHz). That's why I chose a high gain. The "saturation effect" I'm seeing around -50 dBm might well be due to numerical limitations of the algorithm (integral over PSD estimate) used to calculate the power in the band. I have to check on that again. Should I be able to measure linearly over more that 50 dB dynamic range with the USRP/DBSRX combination? > >Furthermore, -165 dBm/Hz is a better sensitivity than my spectrum analyzer > >offers, which I find rather odd. Do these figures make sense? > > Spectrum analyzers rarely have good noise figures. -165dBm/Hz > translates to a roughly 9dB noise figure, which is a little high for the > DBSRX, but not unreasonable. It is better than my spectrum analyzer. Thank you very much for that insight. I was rather suprised, given the 20dB$ price difference. Jens _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
