--- In [email protected], "Leon" <[EMAIL PROTECTED]> wrote: > >> Hello Fred, Alberto and all, >> > > I'm investing an interesting time in the SdR theory. One particular message of this group makes me problem. >> >> The problematic sentence is the following: >> "1° Mix the time domain Q & I signal with a NCO to make a near to zero signal"(this before the FFT) >> It seems that the "NCO" must mean something as "numerical oscillator". I don't suppose that it is an analytic oscillator >> (cos wot / sin wot) but a simple oscillator (cos wot). This simple oscillator applies to I and Q.
> > An NCO (numerically-controlled oscillator) is the same as a DDS. > > 'I' means 'in-phase' and 'Q' means 'quadrature'. > > Leon > Yes, correct, the NCO in Winrad is a numerically controlled oscillator that mimics the working of a DDS, and that generates two components, sin(wt) and cos(wt), which are then used for the full complex mixer that brings to zero IF the signal. 73 Alberto I2PHD
