CST GPS & GNSS Surveying Technologies 1

Question 1

What is the minimum number of satellites a GPS receiver must track simultaneously to compute a 3D position fix?

Accepted Answer

4 satellites

Answer

A minimum of 4 satellites are required: 3 to solve for the three spatial dimensions and a fourth to resolve the receiver clock error, enabling a full 3D position fix.

Question 2

What does the acronym GNSS stand for?

Accepted Answer

Global Navigation Satellite System

Answer

GNSS stands for Global Navigation Satellite System, the umbrella term for all satellite constellations used for navigation, including GPS (USA), GLONASS (Russia), Galileo (Europe), and BeiDou (China).

Question 3

Which reference ellipsoid does the GPS system use as its foundational datum?

Accepted Answer

WGS 84

Answer

GPS uses the World Geodetic System 1984 (WGS 84) as its reference ellipsoid, which defines the coordinate system for all GPS-derived positions.

Question 4

Which GPS survey method produces the highest accuracy for establishing control points?

Accepted Answer

Static differential GPS with post-processing

Answer

Static differential GPS, where two or more receivers simultaneously collect data for extended sessions, achieves sub-centimeter accuracy through rigorous post-processing that eliminates most systematic error sources.

Question 5

What does PDOP measure in GPS surveying?

Accepted Answer

Positional Dilution of Precision

Answer

PDOP (Position Dilution of Precision) quantifies the effect of satellite geometry on 3D positional accuracy; values below 4 indicate favorable geometry, while values above 6 significantly degrade accuracy.

CST - Certified Survey Technician Practice Test

CST - Certified Survey Technician Practice Test

CST GPS & GNSS Surveying Technologies 1