For a Global_position_int ( #33 ) message, the received data is:
Header - FE 1C 5D 01 01 21
Time - 82 CF BF 00
Lat - 18 49 4C 14
Lon - DF BE 48 C0
Alt - 16 B1 15 00
Hgt - A0 00 00 00
00 00 00 00
00 00 CF 34
Altitude = 015B116 Hex is 1421590mm = 1421 m = 4664 feet. The altitude of Socorro is listed as 4603 m
The height above ground level is 10 mm. That number will drift and does go negative.
But I cannot make sense of the Integer Latitude. The common file indicates you divide by 01E7h but that = about 21 degrees. the correct answer is closer to 34 degrees.
Tom