Seiwa SW701i SW701e - Manual (Page 98)

100 User Manual
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User Point
Object you place on the chart identified by its coordinates and displayed on
the screen with a reference symbol (see Mark, Waypoint).
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UTC = Universal Time Coordinated
Time scale based on the rotation of the earth that is used by most broadcast
time services.
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UTM = Universal Transverse Mercator
Metric Grid system used on most large and intermediate scale land topo-
graphic charts and maps.
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Variation
Angle between the magnetic and geographic meridians at any place, expressed
in degrees West or East to indicate the direction of magnetic North from true
North. It changes from point to point, and (at the same point) with time.
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VMG= Velocity Made Good
Destination closing Velocity. The VMG is calculated using the current speed of
the vessel (SOG) and the difference between the current vessel course and
the bearing to the destination.
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WAAS = Wide Area Augmentation System
The Federal Aviation Administration (FAA), in cooperation with other DOT or-
ganizations and DOD, is augmenting the GPS/SPS with a satellite-based aug-
mentation system, the WAAS. It will provide a signal-in-space to WAAS users to
support en route through precision approach navigation. After achieving initial
operational capability, the WAAS will then be incrementally improved over the
next years to expand the area of coverage, increase the availability of precision
approaches, increase signal redundancy and reduce operational restrictions.
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Waypoint
Any point to which one intends to navigate. A sequence of Waypoints makes
up a Route plan.
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WGS-84 = World Geodetic System 1984
Coordinates System or Datum developed by the Defence Mapping Agency
(DMA). It is the default geodetic Datum used by the chart plotter and the GPS.
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Zoom-In
Shows more detail in a smaller area.
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Zoom-Out
Operates similarly to zoom -in, but in the reverse, showing a wider but less
detailed view.
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XTE = Cross Track Error
Distance from the ship's present position to the closest point on a line
between the origin and destinations Waypoints of the navigation.