They might be internal noise from the USRP, turn up the gain input to drown them out. That's what I do.
~Andrew On Sat, Mar 10, 2012 at 6:28 AM, Orkhan Badirkhanli <[email protected]> wrote: > Andrew > > Sorry for the late reply. I am using SBX daughterboard. > > The attachments I included earlier are inaccurate and seems like I was see > that output because I was terminating uhd_fft file using ctrl+c > > Right now I have my noise level at -110dB and I can see different carriers. > The only ambiguity I am facing is that as I change by center frequency by > 0.0001GHz I see some carriers gone and different ones emerged at various > frequencies. > > This is happening in every band. > > > On Thu, Mar 8, 2012 at 7:24 PM, Andrew Davis <[email protected]> > wrote: >> >> The thing in the center is caused by a lot of things, like IQ >> imbalances and the distribution of noise towards zero etc. We all get >> it when the gain is high. Do you have something you are trying to >> detect? Do you have an antenna connected to the right port? What >> front-end board are you using? Try 100MHz and look at some local radio >> stations. >> >> On Thu, Mar 8, 2012 at 8:47 AM, Orkhan Badirkhanli <[email protected]> >> wrote: >> > Hello >> > >> > I've just successully installed gnuradio and connected my new USRP n210. >> > I >> > run uhd_fft.py to test my hardware and it all works well, I activity in >> > the >> > spectrum. >> > >> > The thing is, whatever I set the center frequency, all I see is a >> > carrier at >> > that center frequence at -50dB and "noise" at other frequencies at >> > -70dB. I >> > have included 2 screenshots with center frequencies of 2.4G and 2.4001G, >> > the >> > situation is the same in both of them. >> > >> > I thing there is something really wrong with this. Besides, I remember a >> > few >> > time when I ran uhd_fft.py file, I saw noise at -110dB and several >> > carriers >> > at different frequencies. But that carrier at center frequency was there >> > too. >> > >> > I appreciate any help >> > >> > Thanks >> > >> > -- >> > Orkhan >> > >> > _______________________________________________ >> > Discuss-gnuradio mailing list >> > [email protected] >> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > > > > > -- > Orkhan _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
