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GSR2600
Appendix B
Glossary
Latitude -
An angle generated by the intersection of the semi-
major axis of the datum reference ellipsoid and the ellipsoid
normal (line running perpendicular to the ellipsoid surface) at
the point of interest. Latitude is one of the positional elements
when defining the geodetic coordinates of a point.
Longitude -
The length of the arc or portion of the Earth’s
equator between the meridian of a given place and the prime
meridian expressed in degrees west or east of the prime
meridian to a maximum of 180 degrees.
Low-latency Solution -
A position solution which is based on a
prediction. A model (based on previous reference station
observations) is used to estimate what the observations will be
at a given time epoch. These estimated reference station
observations are combined with actual measurements taken at
the remote station to provide a position solution.
Mask Angle -
See Elevation mask angle.
MSL -
Mean Sea Level
Multipath -
The reception of a satellite signal both along a direct
path and along one or more reflected paths. The reflected signals
are caused by reflecting surfaces near the GPS antenna. The
resulting signal results in an incorrect pseudorange
measurement. Multipath Errors are GPS positioning errors
caused by the interaction of the GPS satellite signal and its
reflections.
NMEA -
National Marine Electronics Association, an
organization that created industry standard ASCII log types that
are used by all receivers.
Observable -
In GPS surveying, the observable is another name
for the raw data being collected (observed) by the GPS receiver.
Obstruction -
Physical feature that blocks the satellite direct line
of site from the point of observation. GPS signals are very weak.
They can be blocked from reaching the GPS antenna by objects
between the antenna and the satellites. Classic examples of
obstructions are trees and buildings.
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