cja (11/05/82)
I was recently made aware of the following (at a drunken brawl, so the confidence intervals are rather small) and thought I'd pass it on. Apparently there exist (or will exist, in the near future) a number of satellites in geosynchronous orbits covering at least the U.S. continental landmass. One of the functions of these satellties is to allow ground stations to determine their own locations at any time by bouncing location identification requests off of the nearest satellite. One of the obvious users of such a system is the military, if they aren't using it already. I suspect they were the prime movers behind the whole thing, anyway. What I am interested in, though, is whether anyone out there knows enough about this system, or knows someone who does, to tell us how private individuals (read: taxpayers) might access those satellites. In other words, what the frequencies are, what the data formats are, services provided, what gets returned, etc. Or is this all classified?
pcmcgeer (11/10/82)
Two Canadian pilots were rescued recently from the wilderness of northern BC because their ELT beep was picked up by a geosynch locator satellite. Rick.
karn (11/11/82)
The rescue of the Canadian pilots took place on 10 Sept 1982, using a Soviet spacecraft, Cosmos 1383. Cosmos 1383 is a polar orbiting navigation satellite that carried SARSAT (Search and Rescue Satellite) transponders as secondary payloads. The Radio Amateur Satellite Corporation (AMSAT) first demonstrated the SARSAT technique in December 1975 using the polar orbiting amateur satellite Oscar-7. The method involves repeating the ELT (emergency locator transmitter) on the downed aircraft via the satellite transponder. By measuring the doppler shift on the repeated signal as the satellite moves, the ELT can be located given that the satellite's orbit and the tracking station's location are known. The SARSAT system isn't fully operational yet, but is in the final stages of engineering development. The US spacecraft element of the SARSAT system will be launched in February, 1983, as part of NOAA-E. Phil Karn