CSI Wireless Seres, Справочное руководство

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Seres Reference Manual
7
1.4.2 Correction Latency
The latency of differential corrections to a lesser extent affects the
achievable positioning accuracy at the remote receiver since the magnitude
of SA was turned to zero in year 2000. Latency is a function of the
following:
•
The time it takes the base station to calculate corrections
•
The data rate of the radio link
•
The time it takes the signal to reach the user
•
The time required for the remote differential receiver to demodulate the signal
and communicate it to the GPS receiver.
•
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 on COAST.
1.4.3 Satellite Constellation Geometry
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 will provide a lower DOP (any satellites seen by either receiver
and not the other, are not used in the position solution). 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.