On 10/27/2010 3:48 PM, Eric Greenwell wrote:
On 10/27/2010 7:20 AM, wrote:
in "awareness mode", of course a led will indicate where the closer
glider is, but still alarms will only be triggered when a deviation
makes the collision a real possibility.

aldo cernezzi
Since the GPS accuracy is probably much poorer than 10 feet, when a
glider comes within 10 feet, I figure the FLARM should consider that a
collision, no?
I don't know what Flarm does in that case, but my guess is the
*relative* accuracy is much better than the *absolute* accuracy. If
that's true, then each glider might have position errors of much more
than 10 feet, but they'll have nearly the same errors, giving a more
accurate separation distance.

Maybe someone more familiar with GPS in this situation can jump in here
and tell us?

Even if the relative GPS position computed by each glider has 0 error,
you still have the problem that at 50 Knots, each aircraft is moving ~
75 ft / second. With FLARM (or ADS-B) only transmitting positions every
second, you can't rely on these technologies to protect you from random
course changes that the systems can't possibly predict, if you are in
close proximity.

--
Mike Schumann