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V
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Variance
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The square of the standard deviation
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VDOP
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VDOP = Vertical Dilution of Precision (height only)
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Vector
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Images defined by sets of straight lines that are defined by the locations of the end-points. Vector graphics require much less
storage space than raster or bitmapped graphics
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Velocity Made Good (VMG)
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The speed you are closing in on a destination along a desired course
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Very High Frequency (VHF)
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Radio frequencies in the band from 30 to 300 MHz
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VMG
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Velocity Made Good. Marine term giving velocity to waypoint taking into effect the course you are steering
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VOG
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Velocity Over Ground. Same as Ground Speed
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W
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WAAS
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Wide Area Augmentation System. A system of satellites and ground stations that provide GPS signal corrections, giving a even
better position accuracy
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WADGPS
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A form of DGPS in which the user's GPS receiver receives corrections determined from a network of reference stations distributed
over a wide geographical area. The corrections are typically supplied in real time by way of a geostationary communications satellite or through a network of ground-based transmitters
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Warm Start
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The ability of a GPS receiver to begin navigating using almanac information stored in its memory from previous use
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Waypoint
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A destination. The coordinates of locations along the desired path as measured in geographic coordinates of longitude and latitude
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WGS 84
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World Geodetic Survey 1984. Geodetic datum for the GPS orbits and consequently positions and baselines computed using them
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WGS84
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World Geodetic Survey 1984. A common map datum reference
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Wide Area DGPS (WADGPS)
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Wide Area DGPS. A form of DGPS in which the user's GPS receiver receives corrections determined from a network of reference
stations distributed over a wide geographical area. The corrections are typically supplied in real time by way of a geostationary communications satellite or through a network of ground-based transmitters
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Widelane
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A linear combination of the L1 and L2 observation (L1 L2) used to partially remove ionospheric errors
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Wide-Lane Observable
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The GPS observable obtained by differencing the carrier-phase observations simultaneously measured, in cycles, on the L1 and L2
frequencies. The effective wavelength is 86.2 centimeters
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World Geodetic Survey 1984 (WGS 84)
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A common map datum reference. Geodetic datum for the GPS orbits and consequently positions and baselines computed using them
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World Radio Conference (WRC)
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An international conference where standards and interference issues are discussed
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WRC
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World Radio Conference, an international conference where standards and interference issues are discussed
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X
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XTE
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Crosstrack Error. The distance you are off a desired course in either direction
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Y
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Y-Code
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The encrypted P-code
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Z
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Z-Count
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The fundamental GPS time unit. It is a 29-bit binary number, of which the 10 most significant bits give the binary representation
of the GPS week number, and the 19 least significant bits give the time-of-week (TOW) count in units of 1.5 seconds
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2D Mode
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2 Dimensional Mode. A two-dimensional GPS position fix that includes only horizontal coordinates, no elevation. It requires a
minimum of three visible satellites
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3D Mode
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3 Dimensional Mode. A three-dimensional GPS position fix that includes horizontal coordinates plus elevation. It requires a
minimum of four visible satellites
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