Tracking flight MH370: ACARS and transponder - ABC News (Australian Broadcasting Corporation)
The head of aviation at the University of News South Wales, Professor Jason Middleton, helps explain just how these systems work and why there is no exact location for the plane.
A rough location can be extrapolated by measuring the time it takes for the ping to be picked up by two satellites.
"[Investigators] are actually using not the signal itself, but the time of reception at different receivers," Professor Middleton said.
"So if you sent out a ping of some sort and it arrives at two receivers and you're exactly halfway between, you can expect that ping will be received – milliseconds later – at the exact same time at both, because it's got the same distance to travel.
"On the other hand, if you're two-thirds closer to one than the other, then that one will receive the signal more quickly than the other."
Professor Middleton says you can use that satellite data to identify a rough line on the surface from where the signal most likely originated.
Any guesses where the second satellite is? The further apart the greater the doppler effect.
If two satellites are used it would be almost impossible to spoof a signal from a fixed point, an idea I raised earlier. You would need to send two pings a split second apart in a way where only one ping was received by each satellite.
For those that want to keep the dream alive that the aircraft has landed;
A drone could have shadowed the flight then turned off and mimicked the ping, but not many drones have speed and endurance to cover the route.
Pingers located on water and land that were activated in sequence.
911 conspirators still claim that ACARS was received after aircraft had crashed.
There was a fast moving ship at the southern search area in the middle of nowhere, a few days ago before the search area was announced..
On the net, so easy to cast doubt on the plausible eh?
Mickjoebill