If we're being nitpicky it was probably neither – multilateration requires taking multiple measurements, drawing circles/lines of equal signal strength (or timing advance) and then intersecting these.
If you just want to home in on a transmitter, there's a much simpler algorithm: Try walking into various directions and keep heading into the one that makes the signal strength nunber go up :) Not sure if there's a name for that.
I was looking at that too, but doesn't that usually imply using a directional antenna, rather than just measuring the received signal strength at different locations?
Nope - as everyone who has looked for a buried avalanche beacon knows. As a matter of fact, depending on the number of burials and the searchers, your optimal search technique may be different.
