These days, we take satellite navigation such as GPS so much for granted. I am told that the best resolution using satellites for civilian use is now down to 30cms but for military uses the resolution is better still. It seems quite incredible that GPS is nowadays routinely embedded in smart phones and we just assume we can find our position with great accuracy. Such accuracy came about as a result of a military project way back in the Cold War.
See http://en.wikipedia.org/wiki/Global_Positioning_System .
Well the averaging of a modern cheap GPS will give the resolution you quoted but using carrier phase methods civil survey grade goes to mm over a short time. Often people use a fixed choke ring antenna and a survey receiver to average a single position to very high resolution then use a version of differential GPS to survey close by positions.
ReplyDeleteThe base rate of 1023KHz gives roughly 300m intervals, so interpolating 1% gives 3m intervals, a nS resolution produces 30cm intervals however the carrier wavelenth is 190mm roughly so resolving 1% of the phase gives 2mm.
Alan
G8LCO
Alan, almost incredible resolution.
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