Hey,

Maybe one day we can quantum entangled two clocks and have a super accurate GPS system.

(by clocks I mean maybe atomic ones, or even quantum entangle two particles that are attached to quantum computers)
-- vtolled, Aug 25 2014

I think this one requires somewhat more explanation. Is the idea to use super accurate pulse timing for positioning?
-- MechE, Aug 25 2014


Is timing the limiting parameter on present GPS?
-- MaxwellBuchanan, Aug 25 2014


Apparently one of them, but not the major one, and it can be corrected down to the centimeter level by using multiple different frequencies. An alternate approach is (if I'm reading it correctly) to use a fixed base station to broadcast correction factors. This also helps correct for signal propagation delays (speed of light in atmosphere being unequal to the speed of light in a vacuum)

The more significant issue is shadowing and reflection. If all the satellites your reciever locks onto are on one side (as if, say, you are standing in the shadow of a mountain), the accuracy gets much worse. Likewise, in that same position, a reflected signal from a satellite off the mountain can make the data worse.

I mean we've already got clocks accurate enough to require automatic correction for relativistic effects at orbital velocities (0.014 seconds/year months at ISS altitude, 4e-10s/s).
-- MechE, Aug 25 2014


Or is part of a marine chronometer for determining longitude?
-- the porpoise, Aug 25 2014



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