Hemisphere GPS V104n, User Manual

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V104n GPS Compass User Guide
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Tilt Aiding
The V104n’s accelerometers (internal tilt sensors) are factory-calibrated and
enabled by default. This allows for a steady heading solution beyond the
volume associated with just a fixed antenna separation. This is because the
V104n knows the approximate inclination of the secondary antenna with
respect to the primary antenna. The search space defined by the tilt sensor
will be reduced to a horizontal ring on the sphere’s surface by reducing the
search volume. This considerably decreases startup and reacquisition times
(see Figure 3-1).
Figure 3-1: V104n’s tilt aiding
Gyro Aiding
The V104n’s internal gyro offers several benefits. It reduces the sensor
volume to shorten reacquisition times when a GPS heading is lost because
the satellite signals were blocked. The gyro provides a relative change in
angle since the last computed heading, and, when used in conjunction with
Table 3-1: Sensor operation summary
Feature Normal Operation Coasting (no GPS)
Heading GPS Gyro
Pitch GPS Inertial sensor
Roll Inertial sensor Inertial sensor
Tilt angle