On 04/15/2013 03:39 PM, Vincenzo Pellegrini wrote: > Hi everybody, > > I have been experiencing some difficulties in obtaining > the same "signal clarity" performance that I used to have with > > uhd_003.004.000-f500b92 > > when I tried to transmit the same samples of the same signal > (also same usrp B100, same XCVR2450 front-end, same frequency =5.8GHz, same > receiving device, same tx/rx antenna positions) > with both: > > uhd_003.005.001 > and > uhd_003.005.002 > > at the following links you can find images of a DVB-T modulation analyzer > exposed to both transmissions. > > www.pellegrini-radio.it/uhd_003.004.000-f500b92.jpg > www.pellegrini-radio.it/uhd_003.005.002.jpg > > If you look at the MER value, a much poorer constellation quality is > evident when operating with the newer UHD and its matched images. > (no performance difference was noticed in this respect between > uhd_003.005.001 and uhd_003.005.002). > > Has this been experienced before? > As somethin changed in between that I should be aware of? >
If 3.4.0 worked, I would definitely give 3.4.5 a try to see if any of the patches or fixes could have inadvertently caused the issue. That will at least narrow down which versions are causing the difference. There was a fix to DSP scaling to prevent clipping. Its possible that the power level is simply lower? What signal amplitude are you using, and does doubling it solve the issue? http://code.ettus.com/redmine/ettus/projects/uhd/wiki/ChangeLog#003004005 -josh > my best regards to everybody > > vince > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
