Humminbird 1158c Combo Installation And Operation Manual page 228

Glossary
Acquisition Time
The length of time that a GPS receiver typically takes to determine a position from at
least three satellites. Humminbird® GPS receivers provide very fast acquisition times (under one minute),
permitting users to get out on the water faster.
Altitude
The height measurement above sea level. Altitude is a measurement that can be provided by GPS.
Bearing (BRG)
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
A navigation device that shows Present Position on a Map, along with Tracks, Waypoints, and
Routes. All Chartplotters are also considered Trackplotters.
Cold Start
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)
(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
Cross Track Error (XTE)
far the boat is off course and also triggers the Off Course Alarm. See
Differential GPS (DGPS)
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
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
Estimated Position Error (EPE)
may experience due to a variety of GPS factors which include satellite position in the sky, signal strength,
and others factors.
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.
GPS (Global Positioning System)
information virtually anywhere on the earth through satellite technology and personal receivers on the
How GPS Works
ground. See
Heading
The direction the boat is pointing and is measured in degrees (i.e. 321°, where 000° is North, 090°
East, 180° is South, 270° is West). Due to wind and waves, the boat is often traveling in a slightly different
direction than it is heading, and therefore Heading is often confused with Course Over Ground. See
Over Ground
.
Map Datum
Refers to a particular survey of the earth's surface that was referenced when creating a chart
(i.e. WGS84). It is important to select the correct Map Datum setting in your fishfinder when comparing GPS
position to a paper chart to avoid slight position inaccuracies. Almost all electronic charts use the WGS84
Map Datum and therefore, they do not require setting changes.
Glossary - GPS & Navigation
The current direction the boat is traveling measured in degrees from North
The straight-line distance of the boat from the intended Track. XTE measures how
A system used to improve the position accuracy of the Department of Defense
A calculation that indicates the potential position inaccuracy the user
GPS provides accurate position (latitude, longitude, altitude)
.
Heading
.
Track
Time to Go
216
GPS & Navigation
.
Speed Over Ground.
and
Course