Humminbird 737 - Manual (Page 132)

123
Altitude: Altitude measures height above sea level. Altitude is a measurement that can be
provided by GPS.
Bearing (BRG): Bearing is the direction to a destination waypoint measured in degrees from
North (i.e. 321°, where 000° is North, 090° East, 180° is South, 270° is West).
Chartplotter: Chartplotter describes a navigation device that shows Present Position on a Map,
along with Tracks, Waypoints, and Routes. All Chartplotters are also considered Trackplotters. All
Humminbird® GPS Combo units are Chartplotters. See Trackplotter.
Cold Start: Cold Start refers to the procedure that a GPS receiver must perform when it does not
have historical information regarding its current location. This procedure typically lasts for
several minutes, and may be experienced upon first power up of the receiver, or if the receiver
has been moved a great distance.
Course Over Ground (COG): Course Over Ground is the current direction the boat is traveling
measured in degrees from North (i.e. 321°, where 000° is North, 090° East, 180° is South, 270° is
West). When the Course Over Ground is equal to Bearing, the boat is said to be “On Course” and
will arrive at the destination in the most efficient manner. COG is often confused with Heading.
See Heading.
Cross Track Error (XTE): Cross Track Error is the straight-line distance of the boat from the
intended Track. XTE measures how far the boat is off course, and also triggers the Off Course
Alarm. See Track.
Differential GPS (DGPS): Differential GPS is a system to improve the position accuracy of the
Department of Defense GPS through the use of secondary “correction signals” broadcast from
ground stations around the coastal United States and on some inland waterways. These
correction signals are provided by the USCG and received by an auxiliary Differential Beacon
Receiver (DBR) that connects to the GPS receiver. The advent of WAAS has largely negated the
need for the added expense of a DBR in the United States.
Distance To Go: Distance To Go is the straight-line distance between Present Position and the
Destination Waypoint. DTG and SOG (Speed Over Ground) are used to calculate Time To Go. See
Time to Go and Speed Over Ground.
Estimated Position Error (EPE): Estimated Position Error is a calculation that indicates the
potential position inaccuracy the user may experience due to a variety of GPS factors which
include satellite position in the sky, signal strength and others factors.
Fix Type: Fix Type indicates whether the GPS receiver is providing 2D fix or 3D fix. A 2D fix
requires only three satellites and provides only latitude and longitude. A 3D fix requires four or
more satellites, and provides latitude, longitude and altitude.