I agree with this analysis unless Isaac tells us he has a carrier and baud synchronizer in his system. If he is looking at raw output from the USRP, indeed the two oscillators (as they would in any real system) shift frequency over time and drift in and out of any phase relationship.
Bob ARRL SDR Working Group Chair Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. "Trample the slow .... Hurdle the dead" -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matt Ettus Sent: Tuesday, July 29, 2008 2:40 AM To: isaacgerg Cc: Discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] Flipping problem isaacgerg wrote: > I am sending a known sequence of samples from one USRP to another using the > Basix RX/TX d'boards setting the frequency to 24e6. > > When I rx the sequence, the correlation of it keeps flipping, but not in a > way that suggests residual carrier. It seems as if I am experiencing an > instantaneous flip. > > My gain on both the RX and TX is set to 500. The signal amplitude I rx is > ~1200. When I run the GRC model, the Rx says I have no residual carrier, > invert is set to false, the dxc frequency is set to -24e6 and the baseband > to zero. On the TX side, I have these same values with the exception of the > dxc freq, it is not set to 24e6. Why the flip?? What do all these things > mean??? > > Is 24e6 a bad freq to use with the basic TX/Rx? > > Thanks in advance! > I believe what you are seeing here is that the two USRPs are on two different frequencies. This is not a fault of the USRP. No two oscillators will be on exactly the same frequency, and so in any practical receiver you must synchronize. Matt _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
