"military GPS is far more accurate than civilian GPS" - is this still true? I don't know how my iPhone GPS triangulates me, but it usually has me located to within 3-5' at all times when I'm walking home.
That has nothing to do with why the iphone is so fast.
Civilian transmission rates on L1 are 10x slower than the military L2 frequency. It takes a full 6 seconds to get a single frame downloaded and that is also hoping your almanac is up to date. (Thankfully AGPS can provide the almanac data by other menas.)
The military version it takes .6 seconds to do the same it takes us civilians to do in 6 seconds. The SA drift is gone now but still the slower speed makes fixing a perfect position slightly more difficult and less accurate.
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"military GPS is far more accurate than civilian GPS" - is this still true? I don't know how my iPhone GPS triangulates me, but it usually has me located to within 3-5' at all times when I'm walking home.
yep. the reason why your iPhone is fast has to do more with AGPS and that it can use wifi access points as references points as well.
I believe that difference went away in 2000: http://en.wikipedia.org/wiki/Selective_Availability#Selectiv...
That has nothing to do with why the iphone is so fast.
Civilian transmission rates on L1 are 10x slower than the military L2 frequency. It takes a full 6 seconds to get a single frame downloaded and that is also hoping your almanac is up to date. (Thankfully AGPS can provide the almanac data by other menas.)
The military version it takes .6 seconds to do the same it takes us civilians to do in 6 seconds. The SA drift is gone now but still the slower speed makes fixing a perfect position slightly more difficult and less accurate.
Military hardware can access encrypted signals that provide greater precision:
http://en.wikipedia.org/wiki/Global_Positioning_System#Satel...