h a l f b a k e r yI CAN HAZ CROISSANTZ?
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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)
[link]
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I think this one requires somewhat more explanation.
Is the idea to use super accurate pulse timing for
positioning? |
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Is timing the limiting parameter on present GPS? |
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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) |
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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. |
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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). |
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Or is part of a marine chronometer for determining
longitude? |
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