What is the term for the setting that stops GNSS receivers from using satellites near the horizon?

• A. Screen
• B. Filter
• C. Guard
• D. Mask

Answer: (D)

The setting is called an elevation mask, sometimes just mask. It defines a minimum elevation angle a satellite must have to be used by the receiver. Satellites below that angle are ignored. This focuses the solution on signals that come from higher in the sky, where the path through the atmosphere is shorter and multipath is less likely, leading to more reliable and accurate positioning. That’s why the mask is the best term here.

Other options aren’t the standard GNSS terminology for this concept. A screen or filter might sound related, but they aren’t the commonly used name for excluding low-elevation satellites. A guard isn’t the term used in this context either. The practice of discarding satellites below a certain horizon threshold is specifically known as setting an elevation mask.