[LAD] Determining Phase

[Gordon JC Pearce]

On Sun, 26 Jun 2011 14:54:48 -0400
gene heskett <gheskett at wdtv.com> wrote:

> I do not see how a repeatable, and therefore measurable quadrature 
> component can be developed in a complex, multi-frequency waveform since the 
> quadrature component is just as frequency dependent as any other method of 
> measurement.

Really?  Because I'm generating some quadrature samples right now - they're how software-defined radios work.  In this case you generate two local oscillators 90 degrees apart and use them to switch a pair of synchronous detectors.  The resulting downmixed RF is now at audio frequencies (just like a direct-conversion receiver) and can be passed to a soundcard, then processed on the PC to extract a particular signal.

See https://github.com/gordonjcp/lysdr if you want to play.

Gordon MM0YEQ