Mesoman and others -
The 406 ELTs currently transmit on one of several different frequencies: 406.025, .028, .037 and .040, depending on when they were built. There are additional freqs reserved for future expansion of the system. A reason for this is a lot of science involving packet theory and collisions between the data bursts from the beacons.
The Doppler frequency is determined by the satellite and position is calculated on the ground at LEOLUTs (LEOSAR local user terminals). This Cospas-Sarsat document goes into much of the gory details:
http://www.cospas-sarsat.org/images/...2_OCT_2012.pdf LUT locations are shown here:
LEOSAR Satellite Coverage
The GEOSAR system consist of geostationary satellites that detect the beacons and GEOLUTs. No Doppler location is determined from them, they provide alerting and data burst relay including position for beacons with a global navigation system.
In development right now is the MEOSAR system, using receivers on GPS, Glonass and Galileo nav satellites. Among the features and advantages of this system is
return-link (two-way) capability between the rescue coordination centers and the beacons. Intial operational capability is scheduled for 2018. References for all of these systems can be found on the Cospas-Sarsat website:
International Cospas-Sarsat Programme
As for beacons transmitting from inside a plane being detected by the satellites, maybe, maybe not. From deep underwater, no. From a crash on land, maybe, maybe not. Lots of factors involved. The most recent published study on the effectiveness of beacons in crashes was published last year by the Australian Transport Safety Bureau.
http://www.atsb.gov.au/media/4126629...-128_final.pdf
For more on ELTs, including a reference for the g-force activation criteria, deployable beacons and more, see this thread spun off from here:
http://www.pprune.org/tech-log/53575...ml#post8376340
Final bit of info, the last week of January of this year was a meeting of the ICAO Asia/Pacific Regional Search and Rescue Task Force in Singapore. 15 of the 44 countries in the region sent representatives, as did ICAO, IMO, IATA and Cospas-Sarsat. Among the countries not in attendance were Malaysia, Vietnam and China. Counted in those which were are Australia, India, Thailand and the US.
Agenda items included (4) Asia/Pacific and inter-regional SAR planning, coordination and cooperation and (5) Asia/Pacific Regional SAR Plan. The minutes note: It was recognized that many States have difficulties in enacting SAR agreements with their neighbouring States.