[Elecraft] KX3 and Quadarature down-sampling

[Alan Bloom]

On Tue, 2011-07-26 at 08:44 -0600, Gary D Krause wrote:
> I've been wondering what Quadarature down-sampling is?  This is the first that 
> I have heard of it.

It's like a two-channel direct-conversion receiver.  The two channels
are on the same frequency but use local oscillators that are 90 degrees
out of phase.  With suitable processing, the in-phase (I) and quadrature
(Q) mixer outputs give both the amplitude and phase of the signal.
Among other things, that makes it possible to suppress the unwanted
sideband of an SSB signal without a crystal filter.

Alan N1AL