Convert Garmin or iPhone weird GPS Coordinates

Question

I am trying to find a way to convert over 500 locations I have saved in my Garmin iPhone GPS app (iPhone 4S using Garmin StreetPilot v2.7), but I can't find a way to convert these coordinates as they are stored in the mylocations.db file. Any recommendations?

name                  latitude    longitude
Starbucks             373512448   1449664512
Wal-Mart Superstore   373473280   1449663232
Subway xin tian di    372450873   1449198830

The Subway one should be N31.21847 E121.47044

The Walmart is N31.30417 E121.50937

AndreJ · Accepted Answer

If you divide those "strange" latitudes and longitudes by 11930465, you get the North and East degree values you expect:

But don't ask me why ;-)

mdag02 · Answer

@AndreJ's answer is right. I just add the reason for this "strange" number :
it seems Garmin stores its angular coordinates using a 32-bit integer, so that gives 2^32 possible values.
We want to be able to represent values up to 360° (or -180 to 180), so each degree represents 2^32 / 360 = 11930465.
So dividing your coordinate by 11930465 will give the decimal value.
By the way, this value encoding is also present in fit files (Flexible and Interoperable Data Transfer) also originating from Garmin.

Convert Garmin or iPhone weird GPS Coordinates

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