Michael Dickens wrote: > On Jan 19, 2009, at 5:46 AM, Bruhtesfa Ebrahim wrote: >> Details: >> - The sampling rate of the original recieved signal from USRP was >> 64MHz/128=500KHz, so I used decimation factor of 500 in the xlating >> filter such that the output baseband signal will have a sampling >> rate of 500KHz/500=1KHz. >> - since the frequency offset of the signal in 1st figure is >> -7.68KHz, i used the opposite freq_offset=7680 in the xlating filter. >> - i used cut off frequency =500Hz and width of transition band=200Hz. > > Everything looks OK "on paper", but I think your filtering will be > tight given the sample rate of the output of the xlating filter. It > very well might be that the offset needs to be the actual value (not > the negative of it) ... I really don't remember any longer. > > My advice is to play with the xlating filter using more bandwidth: > reduce the decimation to, say, 50 (BW = 100k), and change the filter > to be wider and more relaxed (say, BW=25k, transition=15k, in order to > encompass both the original signal as well as the shifted copy of it > if the offset is not exactly correct). I think if you play with the > variables a bit using more bandwidth, you'll figure out what's going on. > > Good luck! - MLD
Thank you so much for all your help Michael!!! I will try it out. Bruhtesfa -- Posted via http://www.ruby-forum.com/. _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
