CSI Wireless DGPS MAX, Reference Manual

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DGPS MAX Reference Manual
5
n
Any data loss that occurs through reception problems
Most of these delays require less than a second, though in some instances,
depending upon the amount of information being transferred, overall delays
of three to five seconds may occur. The effect of latency is mitigated by
new COAST™ technology within the SLX. This technology is especially
valuable in conditions of DGPS signal loss where the age of corrections
increases for each second of signal loss. Consult Section 1.7 for further
information.
Although ionospheric errors are normally removed through differential
positioning, the state of the ionosphere can differ between the base station
and remote user over large distances. As the base station calculates
corrections based on local ionospheric conditions, they may not
completely account for the errors observed at the remote user’s location.
This causes part of the spatial decorrelation that may be observed over
large distances between base station and remote receivers. WAAS models
the state of the ionosphere, providing Ionospheric errors are minimized by
the Virtual Base Station process of the OmniSTAR systems by utilizing a
wide are data format.
The number of satellites visible and their geometry in the sky influences
positioning accuracy. The Dilution of Precision (DOP) describes the
strength of location and number of satellites in view of the receiver. A low
DOP indicates a strong potential for better accuracy than a high DOP.
Generally, more satellites visible to both the reference and remote
receivers provides a lower DOP. Additionally, if the satellites are evenly
spread around the receiver, rather than grouped in a few regions of the
sky, a lower DOP (stronger solution) will result.
Satellite signals received by the GPS receiver by a reflection from an object
can decrease positioning accuracy. These multipath signals increase the
measured range to a satellite as the signal takes a longer route to the GPS
antenna. Certain precautions will minimize GPS antenna sensitivity to
these reflected signals. Operating away from large reflective structures such
as buildings or using special antennas and GPS equipment can help to