About Gps Navigation - Leica MX400 Operating Instructions Manual

About GPS Navigation

About GPS Navigation
This GPS receiver is a precision navigation instrument utilizing the
latest technology available today to provide optimum performance
from the GPS satellite and Beacon land signals received. As with all
other forms of radio signals, the ultimate navigation result is
dependent upon the quality of these signals. Radio signals may, on
occasion, be distorted, jammed, or otherwise incorrect. As a result,
your position accuracy may occasionally be less than that which can
normally be expected.
The Navstar Global Positioning System, commonly referred to as
!
GPS, is a satellite navigation system developed by the U.S. Depart-
ment of Defense to provide both military and civilian users with
highly accurate, worldwide, three dimensional navigation and time.
By receiving signals from orbiting GPS satellites, authorized users
are able to continuously navigate with an accuracy on the order of
16 meters or better, while civilian users are limited to accuracy's of
approximately 100 meters 2D RMS.
A technique referred to as Differential GPS (DGPS), allows users to
obtain maximum accuracy from the GPS system. DGPS requires
the use of two GPS receivers. One receiver, known as the Reference
Station, is placed at a surveyed location, the coordinates of which
are precisely known. The purpose of the differential GPS system is
to use the reference station to measure the errors in the GPS signals
and to compute corrections to remove the errors. The corrections
are then communicated in real-time to the navigators, where they
are combined with the satellite signals received by the navigators,
thereby improving their navigation or positioning. This technique is
effective because many of the errors at the reference station and
navigators are common. The geographic validity of these correc-
tions decreases with distance from the reference station, but the
corrections are valid for navigators hundreds of kilometers from the
reference station.
In order to set up a DGPS system, the user must have a GPS
reference station at a precisely known location, a DGPS navigator,
and a communication link to transmit the pseudorange corrections.
Leica has pioneered the development of the DGPS Beacon System.
This system allows the user to benefit from the accuracy of DGPS
without the need to purchase and maintain a complete DGPS
System (reference stations, transmitting equipment, as well as
Version 3.3
Operator's Manual
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