On Thu, Feb 12, 2009 at 02:17:05PM -0800, Johnathan Corgan wrote: > On Thu, Feb 12, 2009 at 1:20 PM, Bruhtesfa Ebrahim <[email protected]> > wrote: > > > What makes it strange is the dependence on gain.when the linear gain in > > the spectrum panel(usrp_fft.py)is set to 0,the signal at the center(the > > DC)is 5dB higher than the noise level.When I increase the gain, the > > difference between the DC and noise level keeps decreasing and finally > > the DC level is equal to the noise level. > > Specifically, for a linear gain >=20, the signal around DC is not > > visible(it is equal to the noise level). > > Actually, what you're now describing is more like not receiving any > signal at all--the small line at DC is residual DC offset from the > ADC, and the noise is simply that, noise that gets amplified according > to the gain setting. At a certain point the noise power exceeds the > small DC offset. > > Johnathan
Agreed about no (or low) signal, though I think the small line at DC is a truncation artifact in the FPGA. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
