AirNoServicesAustralia:
Also if an aircraft transmits on 121.5 and the sattelite picks that up, then the SAR process starts, and we have to ask aircraft to monitor 121.5 and advise if a beacon is heard.
My understanding is that short transmissions will not be picked up as an ELT. The Satellite requires a constant transmission so that it can use the doppler effect to work out when it has pass overhead / abeam the beacon.
Transmissions from memory simply come up as very short "noise" type bursts.