4 ms·
There's only one satellite, so they only have (as far as we know) the delay time between sending out the ping and hearing a response to determine distance from
by LoganCale 13y ago
There's only one satellite, so they only have (as far as we know) the delay time between sending out the ping and hearing a response to determine distance from satellite to aircraft, with no ability to triangulate the position as something like GPS (which uses many satellites) would do. So they can figure out a large curve around the satellite's position, and the aircraft could have been at any point (within the limits of its fuel capacity) when it sent out that final ping.
- einhverfr 13y agoDistance alone should give you a full circle, but remember you also have processing time which is significant. If they have two possible arcs, this suggests that the same ping was heard by two satellites (and no more), and that these are the places where the difference in time that the satellites heard the pings would work for both satellites. You have basically three intersecting spheres (one is the earth and the other is based on the satellites' light cones). They all meet in two locations. If you had a third satellite, you should be able to determine which of the two locations was right.
- hatbert 13y agoYou're misunderstanding. There is a single circle, which people are calling two arc. That is because they know the airplane can't fly more than a certain distance from its last known position (this reduces the circle to an arc) and because they know where the airplane isn't from radar data (that breaks the one arc into two pieces, which happen to be roughly the same size).
- InclinedPlane 13y agoGPS relies on extremely precise timing as well, and extremely precise knowledge of the orbits of the satellites. If you have 10 millisecond timing on signals that narrows things down to a 3000km range of distances.