How Gps And Trackplotting Work - Humminbird AS GR50 Installation Manual

How GPS and Trackplotting Work

Your Humminbird® uses GPS to determine your position and display it on a grid.
GPS uses a constellation of satellites that continually send radio signals to the
earth. The GPS receiver on your boat receives signals from satellites that are
visible to it. Based on time differences between each received signal, the GPS
receiver determines its distance to each satellite. With distances known, the
GPS receiver mathematically triangulates its own position. With 5 updates per
second, the GPS receiver then calculates its velocity and bearing.
GPS was originally intended for military use; however, civilians may also take
advantage of its highly accurate position capabilities, typically within +/– 2.5
to 10 meters, depending on your conditions and your Humminbird® model.
This means that 95% of the time, the GPS receiver will read a location within
+/– 2.5 to 10 meters of your actual position.
Your GPS receiver also uses information from WAAS (the Wide Area
Augmentation System), EGNOS (the European Geostationary Navigation
Overlay Service), and MSAS (the MTSAT Satellite Augmentation System)
satellites if they are available in your area.
7 Overview