On Mon, 25 Aug 2003 18:16:47 +0000, "Uncle StoatWarbler"
wrote:

On Mon, 25 Aug 2003 19:38:13 +1200, Barry Lennox wrote:

It won't be long before the new generation combines a gps fix with the
distress squawk.

They already exist right now, and have done for about 6 years, but
they are expensive, and that won't come down too much.

Wanna bet? There are moves afoot to push the devices into all sorts of
transport equipment which don't currently have 'em (and arguably don't
need 'em in most parts of the world)

I would, but whatever happens does happen, This has not been discussed
at COSPAS/SARSAT meetings I have minutes for. I think you may be
confused with some other beacons.


The problem is
the 121.5/243 MHz ones cannot support embeddded data, and
COSPAS/SARSAT plans to stop monitoring these freqs in 2006 (I think,
maybe 2008) because of this limitation and the VERY high rate of false
alarms, over 90% in most countries, inc NZ.

That and the satellites are already way past their use-by date, plus there
are the usual interference issues. Txing on 121.5 is awkward (airband)
anyway.

Use-by date? They do get replaced ! "Interference issues"? Like
what, In every ITU region and WARC these frequencies are very
agressively protected. The UWB case is an excellent example.

"Txing on 121.5 is awkward" WTF?! Quite a few A/C carry either a D/F
or homing system that lets them localise the beacon source. In
addition, early every decent A/C Comm Rx has a "Guard" Rx on 121.5 to
detect a beacon. That is the whole point of it, and how the SAR and
aviation infrastructure has grown in the past 50+ years.

The 406 MHz ones certainly support embedded data, but you pay a lot
for them. The big cost driver is the very stable oscillator required,
plus the many thousands required for certification.

This will come down rapidly. The oscillators can be selftweaking off GPS
clocking information, providing ongoing accuracy feedback and
substantially reducing setup costs.

Hmmm, none of the 3 beacon manufacturers I have dealt with over the
past 4 years would agree. The certification costs can only go up.