You email never made it into my mailbox, maybe it got caught as spam.
I am using a USRP with only a DBSRX daughterboard installed. The image
at the following link is a screen capture I took.
Does anyone know why the spike at 921.6 MHz is there?
The spike doesn’t look like it’s from a GSM base station. What country
are you in? Have you tried tuning the usrp_fft.py to the 921.6 MHz
I have observed many of these spikes in other parts of the spectrum
using usrp_fft.py. I looked for them using a real spectrum analyzer
connected to an antenna and did not observe them.
Maybe your USRP is picking up some interference, can you try it with a
different computer and with a different power supply?