In article ,
Tony Verhulst wrote:

The unit won't see other transponders, unless the other transponder is
interrogated by a TCAS-equipped aircraft.


Correct except for the last 4 words. ATC radar also intrerrogats
transponders.

Note that I was responding to a poster discussing what happens
when you are below radar coverage.

--
Bob Noel
(goodness, please trim replies!!!)