Fundamentals of Surveying (FS) Practice Exam

Where are multipath errors most likely to occur?

1. open field of crops

2. dense forest

3. urban area with numerous tall buildings

4. right of way of an interstate

The correct answer is: urban area with numerous tall buildings

Multipath errors occur when a satellite signal reflects off surfaces like buildings, trees, or other obstacles before it reaches the receiver. This can cause inaccuracies in the calculated position because the reflected signal takes a longer path to reach the receiver than the direct signal. In urban areas with numerous tall buildings, the potential for signals to reflect off these structures is significantly heightened. The complex environment creates multiple signal paths, leading to increased risk of multipath interference. This is especially problematic in densely built-up areas, where the surrounding structures can obstruct the line of sight to satellites, causing signals to bounce and arrive at slightly different times. In contrast, while dense forests can also create multipath effects due to tree reflections, the high buildings in urban settings present more pronounced and numerous opportunities for reflection. Open fields of crops and right-of-way areas of interstates typically have fewer obstructions, resulting in clearer direct line-of-sight to the satellites and thus a lower likelihood of multipath errors.