I believe the new Garmin Rino GPS's have a built in 5km range radio
transmitter/receiver which is capable of showing the locationand snail
trail of other similar units in the area. Sounds like quite a useful
feature. Not quite what you are asking for but a step towards it.

Cheers

Andy


"Karl Osen" wrote in message ...
Hello,
Is anyone aware of anti-collision systems (projects or products) for gliders
based on GPS and short range radio? Such systems broadcast position at
random times, allowing equipped vehicles (e.g. gliders) to be informed when
they have a dangerous trajectory relative to other equipped gliders).
Rgds
Karl Osen