Modern Surveying Technologies MCQ with answer and solution

Concept

In GPS relative (differential) surveying, a short baseline is one where errors at both receivers are nearly the same, generally less than about 50 km.

Formula

NONE

Step-by-step solution

1. In relative GPS surveying, two receivers observe the same satellites at the same time. 2. The line joining the two receivers is called the baseline. 3. When the baseline is short, atmospheric errors (ionosphere, troposphere) and orbit errors are almost the same at both ends, so they cancel by differencing. 4. GPS texts commonly call baselines up to about 50 km short baselines. Longer baselines (above 100 km) are called long baselines. 5. So the answer is: less than 50 km.

Explanation

In the short baseline method, the two GPS receivers are close enough that most errors are common to both and cancel out. GPS texts generally treat baselines less than about 50 km as short. This gives high accuracy with simple processing.

Shortcut

Short baseline < 50 km, long baseline > 100 km.