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High precision wearable GPS

Useful in urban canyons as well as real ones
  [vote for,

Most smartphones and many fitness trackers have built-in GPS. But their accuracy could be better.

I'd like a kit containing two wearable GPS receivers - with bluetooth links to each other and a smartphone (iOS or Android) running an app to correct GPS data on the go. Data from two units even a small distance apart can be used to correct for multi-path and other errors. Accelerometers in each unit (likewise common in current fitness trackers and smartphones) can be used for track smoothing.

kdf, May 12 2020

Combining multiple GPS receivers to enhance relative distance measurements https://www.semanti...ded09d91febc296dc90
[kdf, May 12 2020]

Combining inexpensive GPS to improve accuracy https://docs.lib.pu...=open_access_theses
[kdf, May 12 2020]

1966 Woodford/Nakamura Report https://www.xyht.co...-study_Redacted.pdf
Declassified version, the good stuff is missing [kdf, May 13 2020]

GPS Declassified https://www.gpsdecl...t-gps-declassified/
[kdf, May 13 2020]


       // Data from two units even a small distance apart can be used to correct for multi-path and other errors. //   

       No, it can't - not to any useful extent. You need DGPS, or a receiver in a static position with a multibird fix over a prolonged period.   

       This approach has been extensively evaluated as a means of terminal guidance and rejected. It gets proposed from time to time and the fundamental math kills it again and again.   

       Every now and again a vendor comes along purporting to offer a software solution but they all rely on having a minimum solid 4-bird fix with a mid-level distribution. Low obscuration (the "urban canyon" effect) always defeats it. High obscuration is not so bad but still tends to make it impractical.
8th of 7, May 12 2020

       “useful extent” depends entirely on intended use. Likely not useful for landing a plane. Not needed for driving to the park. Potentially useful for retracing your exact steps through the woods, back to the spot where you hid the bag of ... er, the geocache or something like that.   

       Oh, and VERY appealing to moneyed geeks ... who already know EXACTLY where they were ... but want to look at the track later and want to see it mapped ON the trail they used, not zag-zigging dozens of feet off to either side.
kdf, May 12 2020

       // depends entirely on intended use. //   

       "Putting a missile through Brezhniev's bathroom window" was the original specification for GPS.
8th of 7, May 13 2020

       Missile guidance isn't the “intended use” of this HB idea either, but I know you like that kind of stuff. Linked some light reading for you.
kdf, May 13 2020


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