(comments inlined) On Wed, Apr 05, 2006 at 02:02:23PM -0400, Robert McGwier wrote: > Yes. Here is what you are missing: > > Let us concentrate (as does your nice animated gif) on one channel in > the OFDM. Yes, what's depicted are all decoded symbols in one OFDM frame.
> Let us suppose you have a variable delay into the signal after its > onset. This will happen with probability one because your clock and the > transmitter clock will not be the same except in your computer simulation. Agreed. But this delay will only be fractional, as I can determine the exact start by correlation. The oscillators are pretty stable, so I can exactly time one symbol. The offset will thus be fractional and constant. I verified this by correlating every OFDM symbol with itself. This shows that the cyclic prefix does not move. > If you took the FFT beginning (say) 39 samples into the symbol at t, > and then 52 samples after the beginning time for symbol at t+1, > this will be an additional rotation due to the frequency offset of this > channel from zero. Notice this means that every channel will have a > different rotation which will be a multiple of the frequency offset from > correct and the difference in time after symbol onset you go into the > symbol to take the FFT. I agree. But, as stated above, my time offset is fractional and constant. Jens _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
