Sensor Reference Frames; Geodetic Frame - Lord MicroStrain 3DM-GX4-45 User Manual

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3DM-GX4 -45 Inertial Navigation System
Sensor Measurements
User Manual

4.4 Sensor Reference Frames

4.4.1 Geodetic Frame

The World Geodetic System is the standard for cartography and navigation. The latest
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revision, WGS84, is the reference coordinate system for GPS, and the 3DM- GX4-45
reports position using this coordinate frame. It also calculates the magnitude of the local
gravity vector using the WGS84 reference formulas.
The WGS coordinates are latitude (φ), longitude (λ), and height (h) above the reference
ellipsoid. Latitude ranges from -90 degrees at the South Pole to 90 degrees at the North
Pole. Longitude ranges from -180 to 180 degrees, with 0 degrees being the prime meridian.
The -180/180 degree switchover occurs in the middle of the Pacific Ocean and includes a
section of the International Date Line. The model takes into account the oblateness of the
Earth's surface.
A point (P) on or above the Earth in the WGS84 coordinate system is notated as: latitude
(φ), longitude (λ), and height above the reference ellipsoid (h).
Figure 19 -
World Geodetic System (WGS84) Reference Ellipsoid
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