On Mon, Sep 29, 2008 at 4:40 PM, Johnathan Corgan <[EMAIL PROTECTED]> wrote: > On Mon, Sep 29, 2008 at 11:52 AM, sri ram <[EMAIL PROTECTED]> wrote: > >> 3. However, for a tx. stream of 1's and 0's mixed, I still see the received >> amplitude (real part) showing the beat frequency continuously and not going >> to 0 for the 0 bits. > > When you send alternating 1's and 0's, you are creating a baseband > square wave of constant power. The DC offset is half your baseband > transmit amplitude, and that energy at DC is upconverted to your > carrier frequency. On receive, since you have a frequency offset, you > will see a continuous beat frequency resulting from this constant > carrier. Superimposed on this will be the harmonics of your square > wave up to the Nyquist limit of your baseband sampling rate, or up to > the cutoff frequency of the RRC filter if it is in use.
Don't some of the daughterboards also have some AGC built in? I can see if the interpolation rate is not high enough, the signal power will not go down enough (especially after the RRC filtering) to really look like much of a difference if any due to the AGC circuitry and other transients that may occur on signals quickly coming on then off. Please correct me if I am wrong, but I think using a very large interpolation rate might help clarify the situation. Brian _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
