ST2276
Scientech Technologies Pvt. Ltd.
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Digital :
Generally, information is expressed, stored and transmitted by either analog or digital
means. In a digital form, this information is seen in a binary state as a one or a zero, a
plus or a minus. The computer uses digital technology for most actions.
Dilution of Precision – DOP :
A description of the purely geometrical contribution to the uncertainty in a position
fix. Standard terms for the GPS application are : GDOP : Geometric (3 position
coordinates plus clock offset in the solution) PDOP: Position (3 coordinates) HDOP :
Horizontal (2 horizontal coordinates) VDOP: Vertical (height only) TDOP : Time
(clock offset only) RDOR Relative (normalized to 60 seconds)
Distance root mean square (drms) :
The root-mean-square value of the distances from the true location point of the
position fixes in a collection of measurements. As typically used in GPS positioning,
2 drms is the radius of a circle that contains at least 95 percent of all possible fixes
that can be obtained with a system at any one place.
Dithering :
The introduction of digital noise. This is the process the DoD used to add inaccuracy
to GPS signals to induce Selective Availability.
DOP :
See dilution of precision
Doppler-aiding :
A signal processing strategy that uses a measured doppler shift to help the receiver
smoothly track the GPS signal. Allows more precise velocity and position
measurement.
Doppler shift :
The apparent change in the frequency of a signal caused by the relative motion of the
transmitter and receiver.
Earth-centered earth-fixed – ECEF :
Cartesian coordinate system where the X direction is the intersection of the prime
meridian (Greenwich) with the equator. The vectors rotate with the earth. Z is the
direction of the spin axis.
ECEF :
see earth-centered earth-fixed
Elevation :
Height above mean sea level. Vertical distance above the geoid.
HiK-Consulting
