OmniSTAR 5220HP, User Manual

Page: 19 / 83

OmniSTAR 5220HP User Manual
Issue 1.32 12/2010
19
Position Dilution of Precision (PDOP)
The Position Dilution of Precision (PDOP) is a measure of the satellite
geometry. The closer to 1 the PDOP value, the more accurate the GPS
position will be.
Satellite elevations
The signal from a satellite that is low on the horizon will travel a greater
distance through the atmosphere. This results in lower signal strength and a
delayed reception, thereby causing erroneous and noisy data. By default the
5220HP is configured to ignore any GPS satellites that have an elevation
angle lower than 8
°
.
OmniSTAR corrections
For accurate positioning it is essential that the differential corrections are
received. In order to ensure reception of the OmniSTAR satellite signal the line
of sight towards the satellite must not be blocked by objects such as trees and
buildings. To find out which OmniSTAR satellite(s) can be received at your
geographic position, please visit the survey planner website
(
http://www.surveyplanner.com ).
Interference
Although the 5220HP has been designed to provide optimal system
performance under most circumstances, due to the nature of radio
communications it is possible, that the system performance degrades as a
result of local interference sources. When interference levels are too high, the
5220HP may even lose lock to either the OmniSTAR satellite or the GPS
satellites.
Interference sources include radio and television transmitters, radars,
microwave ovens, poorly shielded spark plugs and aeronautical radio
navigation systems, in short: any device producing electromagnetic energy
(directly or through harmonic frequencies) in the 1525 - 1580 MHz band.