Question

Which statement is not correct for GPS?

• A. It does not work in tunnels.
• B. It does not work underwater.
• C. It gives coordinates in local datum.
• D. It gives ellipsoidal heights.

Hint:

GPS uses WGS84 — a global datum, not a local one.

Answer 1

The Correct Option is C

GPS functions by receiving signals from satellites; these signals cannot penetrate solid structures or water. Consequently, GPS is unreliable in tunnels and underwater, validating statements (A) and (B). GPS determines positions within a global reference frame, typically the WGS84 datum, which is a worldwide geodetic datum, not a local one. Local datums necessitate transforming global coordinates. Furthermore, GPS provides ellipsoidal heights relative to the reference ellipsoid. Therefore, statement (C) is incorrect, as GPS does not default to providing coordinates in a local datum.