Replying a bit late here...
Jens Elsner wrote:
As Eric Matlis a while ago (see link to thread at the bottom), I would
like to calibrate my USRP/DBSRX combination for measurements. As noted,
the USRP is not a measurement device, but nevertheless I'd like to give
it a try. My application are GPS based measurements in the GSM downlink
band.
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?
Offset (to convert from dB to dBm): -177.7
Noise floor: -112.5 dBm, sensitivity -165 dBm/Hz (NF: 8.7 dB at 20 degrees)
Linear measurement range: -100 dBm to -50 dBm
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.
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.
Matt
_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
