why did old (like 90s/2000s) GPS take up to 15 minutes to get a lock, in giant bulky units, but my running watch gets it in 15 seconds?

Question

why did old (like 90s/2000s) GPS take up to 15 minutes to get a lock, in giant bulky units, but my running watch gets it in 15 seconds?

In: 3751

Answer 1

Part is that they cheat. Turn your phone off and fly to another country and turn it on and it will take a noticeably long time. But phones being always on means it can store and update your location and remember where you were. So it gets to start with the hypothesis you are still around where you were last time it checked.