User's Guide

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PDOP
Position Dilution of Precision. PDOP is a DOP value that
indicates the accuracy of three-dimensional
measurements. Other DOP values include VDOP
(vertical DOP) and HDOP (Horizontal Dilution of
Precision).
Using a maximum PDOP value is ideal for situations
where both vertical and horizontal precision is
important.
Postprocessing
Postprocessing is the processing of satellite data after it
has been collected, in order to eliminate the error. This
involves using computer software to compare data
from the rover with data collected at the base station.
Real-Time Differential
GPS
Also known as a real-time differential correction or
DGPS. Real-time differential GPS is the process of
correcting GPS data as the user collect it. Corrections
are calculated at a base station and then sent to the
receiver through a radio link. As the rover receives the
position, it applies the corrections to give the user a
very accurate position in the field.
Most real-time differential correction methods apply
corrections to code phase positions. RTK uses carrier
phase measurements.
While DGPS is a generic term, its common
interpretation is that it entails the use of
single-frequency code phase data sent from a GPS base
station to a rover GPS receiver to provide sub-meter
position accuracy. The rover receiver can be at a long
range (greater than 100 km (62 miles)) from the base
station.
Reference Station
See base station
Rover
A rover is any mobile GPS receiver that is used to
collect or update data in the field, typically at an
unknown location.
RTCM
Radio Technical Commission for Maritime Services. A