NavCom SF-2040 Rev.F - Manual (Page 83)

SF-2040 User Guide – Rev. F
dual-frequency a type of GPS receiver that uses
both L1 and L2 signals from GPS satellites. A dual-
frequency receiver can compute more precise
position fixes over longer distances and under more
adverse conditions because it compensates for
ionospheric delays. The SF-2040 is a dual frequency
receiver.
dynamic mode when a GPS receiver operates in
dynamic mode, it assumes that it is in motion and
certain algorithms for GPS position fixing are enabled
in order to calculate a tighter position fix.
EGNOS (European Geostationary Navigation
Overlay Service) a European satellite system used
to augment the two military satellite navigation
systems now operating, the US GPS and Russian
GLONASS systems.
elevation distance above or below Local Vertical
Datum.
elevation mask the lowest elevation, in degrees, at
which a receiver can track a satellite. Measured from
the horizon to zenith, 0º to 90º.
ellipsoid a mathematical figure approximating the
earth’s surface, generated by rotating an ellipse on its
minor axis. GPS positions are computed relative to
the WGS-84 ellipsoid. An ellipsoid has a smooth
surface, which does not match the earth’s geoidal
surface closely, so GPS altitude measurements can
contain a large vertical error component.
Conventionally surveyed positions usually reference a
geoid, which has an undulating surface and
approximates the earth’s surface more closely to
minimize altitude errors.
epoch literally a period of time. This period of time is
defined by the length of the said period.
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