Humminbird 4090501 How GPS Works, See, and, for more information, •View current position, •Save tracks, waypoints, and routes, •View current track (breadcrumb trail)

How GPS Works

Your 300 Series™ Fishfinder also supports GPS (Global Positioning System) and chartplotting. It uses GPS and sonar to determine your position, display it on a grid, and provide detailed underwater information.

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 once per second updates, 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 +/- 4.5 meters, depending on conditions. This means that 95% of the time, the GPS receiver will read a location within +/- 4.5 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.

The following GPS functionality is currently supported by the 300 Series™ Fishfinder when it is connected to the included GPS receiver:

•View current position•View current track (breadcrumb trail)•View precision speed and heading from your GPS receiver•Save tracks, waypoints, and routes•Travel a route and navigate from one waypoint to the next

See SD Card Slot, Chart View, and Introduction to Navigation for more information.

7 How GPS Works