Sigh... (USA)

Also, the glider
above would almost certainly have it's transponder antenna on the
bottom, while the glider below would have it's PCAS antenna "on top"
(glare shield mounted) and have no trouble receiving it.

Eric, only if they both have both transponder and PCAS. Re the
stronger signal, you may well be right – I don’t know.

But PCAS of course does not distinguish between proximity but going to
miss, and proximity and going to hit. My unit also only knows in
1/10ths of a mile the approximate distance. Still, better than
nothing, of course.

Chris N

On 6/9/2012 7:33 PM, Chris Nicholas wrote:
Eric, only if they both have both transponder and PCAS. Re the
stronger signal, you may well be right – I don’t know.

One could have the PCAS, the other could have the transponder, and the
PCAS glider would be alerted to the other glider. Better, of course, if
they both had PCAS and transponder.

Transponders do have very powerful transmitters, and it is one reason
they cost as much as they do. Look at the specifications at any website
selling them - the power ranges from about 130 to 250 watts (our
communication radios are typically 5 to 7 watts). That power is needed
to reach the ground radars that might be 30 to 150 miles away.

Flarm, including PowerFlarm, is designed for air to air ranges of a few
miles, and doesn't need very much power to do so.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)