[time-nuts] Basic question regarding comparing two frequencies

Stanley Reynolds stanley_reynolds at yahoo.com
Sun Jul 25 12:33:49 EDT 2010

My attempt to understand your diagram, not sure about how the quadrature hybrid 
is connected.


----- Original Message ----
From: J. Forster <jfor at quik.com>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Sun, July 25, 2010 10:29:23 AM
Subject: Re: [time-nuts] Basic question regarding comparing two frequencies

There is a cute way to use a scope.

It requires a power splittere, a quadrature hybrid, and two mixers (all
appropriate for the frequencies you are comparing), and an X-Y scope.
Mini-Circuits sells appropriate parts. The stuff is hooked up like this:

              X Axis
      S      |      H
      P ---- MIX ---- Y
REF 1--L              B -- REF2
      I ---- MIX ---- R
      T      |      I
              Y Axis  D

The 'scope display will be roughly a circle if the frequencies are a bit
different and the spot will go around CW or CCW depending on which Ref is

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