Designing a low-cost mobile tracking system for communication with a medium earth orbit satellite

An essential part of satellite communication is the orientation of the antenna, which can be difficult to ascertain on mobile platforms such as ships. While equipment to measure orientation accurately at sea exists, current solutions are expensive. This paper describes work toward an antenna orientation system using low-cost Global Position System (GPS) receivers. We investigated two methods: one using the spatial difference between multiple GPS units at the vertices of a polygon, and the other using the differences over time measured using a single GPS unit. We tested the antenna orientation system with the Omnispace F2 satellite at the US Electrodynamics, Inc. (USEI) teleport in Brewster, WA. Although non-correlated systematic errors in the GPS receivers made the multiple-GPS system impractical, the time-differential method was able to maintain a satellite lock for the majority of a simple test course. The reliability of this solution may be further improved using a gain-based correction algorithm.