Bob- > In your sixteen QAM and other figures I see two effects. > > Notice just the slightest hint that arcs through the top four > constellation points in the 16 QAM is not straight. This curvature is > caused by nonlinearity. > > Your result almost surely can NOT be clock jitter. If you had a lot of > clock jitter, the pictures would look much worse. Notice the > dispersion gets larger as your proceed away from the origin. This is > almost surely phase noise in some oscillator.
"Phase noise" of an oscillator to me means jitter. Can you clarify? Do you mean a sinusoid oscillator that has some issue with shape; i.e. non-linearity? Thanks. -Jeff > Per Zetterberg wrote: > > Dear all, > > > > I am experimenting with OFDM between two USRPs. Unfortunately, I am not yet > > able to master the gnuradio framework so I have made my own implementation. > > The results are given in the link below. > > > > http://www.s3.kth.se/~perz/usrp/OFDM_results.pdf > > > > > > How does this compare with the gnuradio OFDM implementation ? > > > > What is the cause of the problems. Clock jitter ?, non-linearities ? > > > > > > BR/ > > Per Zetterberg _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
