On 05/03/2012 01:08 PM, Jason Tran wrote: > Hi All, > > Here are images of what I'm seeing in my setup. > > Pictures of Images/Spikes: > > center freq set to 2.4GHz. random image (oscillioscope) > http://img585.imageshack.us/img585/5871/img20120503124151.jpg > > > center freq set to 2.4GHz. images +/- 0.5MHz (uhd_fft.py) > http://img801.imageshack.us/img801/3015/imagesonuhdfft.png > >
I believe that you are seeing the LO of the XCVR2450. The default behaviour when tuning the transmitter on this board is to tune the LO with an offset such that it stays out of your passband. So I dont think is is harming the deframing and demoding of packets. You might try messing around with some other parameters, gain, symbol rate, modulation type. > Pictures of Clean Signal: > > center freq set to 0; Tx "defaults" to 4.8GHz but is actually 2.4GHz > (uhd_fft.py): > http://imageshack.us/photo/my-images/213/noimagesuhdfft.png/ > > > (oscilloscope version) > http://img801.imageshack.us/img801/4141/img20120503124257.jpg > > I think whatever screwy thing is happening to make the tune request clip to 2.4GHz is affecting the logic that decides the LO offset. I'm not sure at what level the coercion is happening. Pardon me, I am away from my USRP :-) If you run one of the examples that comes with UHD try tx_waveforms --freq=4.8e9 --rate=1e6 and see the warning it prints about the tune frequency. -josh _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
