Darrel Toepfer wrote in
:

Are you using the included antenna or an external one?

I'm using the included antenna still. There is no doubt that a dual
(high-low) antenna would be a big help. However, I often see the threat
aircraft pass directly in front of my plane and nothing from the ATD
until it is well past. The ATD antenna had a clear view - so I suspect
the problem is more with shadowing of the transmitting antenna.
Unfortunately, there is nothing that can be done about this on the ATD-
equipped aircraft.

I like the fact that the new model allows you to check your own
equipments ouputted signals...

True. Even the ATD-200 had a light to alert you that you were
responding to a ping. And my GPS tells me what my xpndr encoder is
saying. That still leaves faults in the xpndr itself (transmitting
false information) but not a big problem.

I'm sure the plane itself will always act as a shield, depending on
where the target aircraft might be located...

True. I know aircraft with Skywatch installed, complete with the top
and bottom antennas. That's a $20K+ system, and still they see aircraft
"appear and disappear" in certain quadrants. Heck, even ATC (which
typically has a better geometry) will see aircraft drop the Mode-C when
the plane is turning, or when some other part of the plane intervenes.
That could be fixed with a more sophisticated xpndr system, but no one
is going to propose that much money to upgrade the entire fleet.

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------