Differential Operation - Hemisphere GPS V104n User Manual

V104n GPS Compass User Guide
signal to reach the GPS antenna. The GPS receiver uses a complex algorithm
incorporating satellite locations and ranges to each satellite to calculate the
geographic location and heading. Reception of any four or more GPS signals
allows the receiver to compute three-dimensional coordinates and a valid
heading.

Differential Operation

The purpose of differential GPS (DGPS) is to remove the effects of selective
availability (SA), atmospheric errors, timing errors, and satellite orbit errors,
while enhancing system integrity. Autonomous position capabilities of the
V104n will result in position accuracies of 3 m 95% of the time. In order to
improve position quality to better than 1.0 m 95%, the V104n is able to use
differential corrections received through the internal SBAS demodulator.
Automatic SBAS Tracking
The V104n automatically scans and tracks SBAS signals without the need to
tune the receiver. The V104n features two-channel tracking that provides an
enhanced ability to maintain a lock on an SBAS satellite when more than one
satellite is in view. This redundant tracking approach results in more
consistent tracking of an SBAS signal in areas where signal blockage of a
satellite is possible.
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