User Manual

HiPerII Chapter 1
Essential Components for Quality Surveying
Achieving quality position results requires the following elements:
 Accuracy - The accuracy of a position primarily depends upon the satellite geometry
( Geometric Dilution of Precision, or GDOP ) and the measurement (ranging) errors.
 Differential positioning ( DGPS and RTK ) strongly mitigates atmospheric and orbital
errors, and counteracts Selective Availability ( SA ) signals the US Department of
Defense transmits with GPS signals.
 The more satellites in view, the stronger the signal, the lower the DOP number, the
higher positioning accuracy.
 Availability - The availability of satellites affects the calculation of valid positions. The
more visible satellites available, the more valid and accurate the position. Natural and
man-made objects can block, interrupt, and distort signals, lowering the number of
available satellites and adversely affecting signal reception.
 Integrity - Fault tolerance allows a position to have greater integrity, increasing accuracy.
Several factors combine to provide fault tolerance, including:
 Receiver Autonomous Integrity Monitoring ( RAIM ) detects faulty GNSS satellites and
removes them from the position calculation.
 Five or more visible satellites for only GPS or only GLONASS; six or more satellites
for mixed scenario
 Satellite Based Augmentation Systems ( WAAS, EGNOS, and so on ) creates and
transmit, along with DGPS corrections, data integrity information ( for example,
satellite health warnings ).
 Current ephemerides and almanacs.
Conclusion
This overview simply outlines the basics of satellite positioning. For more detailed information,
visit the Sokkia Topcon website.
Receiver Overview
When power is turned on and the receiver self-test completes, the receiver's 72 channels
initialize and begin tracking visible satellites. Each of the receiver's channels can be used to
track any one of the GPS or GALILEO signals. The number of channels available allows the
receiver to track all visible global positioning satellites at any time and location.
HiPerII Chapter 1