How Gps Works - Humminbird 698ci HD SI Combo Operation Manual

How GPS Works

Your 600 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 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 Navigations 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 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 Chart View and SD Memory Card Slot: Add Maps to Your Fishfinder for
more 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
5 updates per second, the GPS receiver then
calculates its velocity and bearing.
7 How GPS Works