The above figure is from “AA-30/AA-54 Analyzers, How it works?”
http://www.rigexpert.com/index?s=aa54&f=inside
The bridge circuit is the same as the one shown in my previous post:
Directional Bridge (November 5, 2013).
Instead of down-converting the signals to be A/D connverted, I am simply using an oscilloscope to directly observe the amplitude and the phase of the signals.
The red (CH1) and yellow (CH2) traces correspond to the signals obtained from the bridge, and the green trace to CH1 – CH2.