On Wed, 2011-05-25 at 08:51 -0700, Lebowski80 wrote: > Hello everyone > > I’m using an USRP with a XCVR2450 daughter board working at 2.4 - 2.5 GHz. I > want to find a threshold between thermal noise and signals energy using the > script usrp_spectrum_sense.py and sensing from 2.400 GHz to 2.500 GHz. To do > that, I replaced the WiFi antenna with a resistor of 50 Ω to measure the > noise. I obtained a very strange peak at the beginning of the bandwidth > (around 2.405 GHz) and this result was totally unexpected because I supposed > to sense only thermal noise without any particular peak. So, I repeated the > experiment from 2.420 GHz to 2.500 GHz and I achieved the same peak always > at the beginning of the bandwidth (in this case around 2.425 GHz). > Therefore, I'm quite sure this is a problem linked to USRP or to the script > usrp_spectrum_sense.py, isn’t it? Can someone give me a hint about that > please?
The USRP is not a measurement receiver, and some small spurs are to be expected. You can plan for this, or work around it by changing the LO offset at a given center frequency using the advanced tuning parameters: http://www.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__request__t.html --n > > Regards > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio