Thank you very much for the explanation, Charles. That explains what I see on the Spectrum Analyser and why I was getting some weird signals in Matlab...
Thank you, Angilberto. --- Charles Swiger <[EMAIL PROTECTED]> wrote: > On Tue, 2006-07-18 at 08:57 -0700, Angilberto Muniz > Sb wrote: > > Folks, > > I'm confused with -i option in siggen.py... > > > > If I want to generate a pure 1MHz sine wave > centered > > at 10MHz carrier is it correct to use: > > > > siggen.py --const --sine -f 1e6 -c 10e6 > > > > or should I use: > > > > siggen.py --const --sine -f 1e6 -c 10e6 -i 32 > > > > or neither one ??? > > > > Would somebody elaborate on that? > > > > [ posting to list in case I make any mistakes, pls > correct ] > > Quick answer: Either one, and don't use --const, > just --sine. > > That must be an older version of usrp_siggen.py as > the > latest does not have a -c option. You would use just > --sine, > as --const is for a constant (DC) signal. > > In that version you could specify waveform frequency > before > upconverting to the output frequency, the > upconverter (DUC) > frequency and the interpolation. It looks like > this: > > (waveform) ----> (duc) -----> (output freq) > ^ ^ > usb_rate 128e6 > > Interpolation is the ratio of DAC rate (128e6) to > the usb_rate, > default is 64 and you ask for 32 above. So for an > interpolation > of 32 the usb_rate would be 4MHz (128e6 / 32) so > your waveform > could be anything from -2 to +2Mhz and the output > would be the > DUC freq plus the waveform frequency. > > If you use siggen.py --sine -f 1e6 -c 10e6 -i 32 > > you would get an output at 11Mhz. IF you use default > interp = 64 > you might want to use a smaller waveform freq as > 1MHz would be > right at the edge of the usb_rate and it loses > amplitude some. > Something like siggen.py --sine -f 50e3 -c > 10.95e6 > > In the newer versions -f is the DUC frequency and -w > is the > waveform frequency. > > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
