On Fri, Aug 28, 2009 at 12:56 PM, Douglas Geiger<doug.gei...@bioradiation.net> wrote: > That sounds like it could be a frequency offset between TX and RX. You > say you aren't synchronized (which I interpret to mean you don't lock > the clocks of the TX and RX together somehow) - do you have a costas > or similar carrier offset recovery block/process on your receiver?
Correct, the USRPs are physically disconnected. Right now, the graphs are: sig_source_f -> float_to_complex -> head -> usrp.sink_c usrp.source_c -> file_sink (on the other PC) TX usrp sends the first 1000 cycles of a 2MHz sine wave (sig_source with 4MS/s), then the "training graph" is disconnected and another one with the QAM modulator kicks in. Both scripts tune to 2.5G. The strange thing is no matter what frequency I set the sig_source to (already tried 1.5k, 2k, 1M and 2MHz, sampling frequency 4MS/s), the fft on matlab always shows a single impulse at aproximately -3kHz. In the time domain, the signal is sinusoidal on both real and imaginary parts, when I expect it to be only real since the carrier has (should have) been removed. I believe I am missing some trivial concept here. -- Igor Almeida _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
