This is a phenomenon that unfortunately often occurs when working with a GNSS Receiver in an area where there are many objects that disrupt the view of satellites. Not enough satellites will result in an RTK Fix or a multipath error. In the case of a multipath error, the signal is delayed by the many reflections, for example from buildings, and therefore takes longer to reach the target. It can also happen that it arrives several times, which makes the visible signal unusable.
As discussed in the previous alinea, the environment you are working in can have a great influence on the accuracy you want to achieve.
Therefore, it is very important to ask the following questions:
- What level of accuracy do I want to achieve?
- What kind of environment do I work in?
Here are two simple examples:
A farmer wants to take land measurements on his land. Generally, the only interference he encounters is from a few random trees on his land. Does the farmer need a powerful GNSS antenna to get centimeter accuracy? 9 times out of 10, no. He can most likely do his job with a simple RTK GNSS receiver.
However, a surveyor more often finds himself in urban environments such as cities where he needs to map and locate pipes, cables, sewers etc. His GNSS antenna has to deal with much more multipath interference such as buildings, fences, trees and light poles. A more powerful GNSS receiver is recommended in these environments.