Hemisphere GPS V104s, User Manual

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Chapter 3: Operation
Hemisphere GNSS’ GPS Technical Reference describes the commands and
methodology required to recalibrate, query, or change the sensors status.
Tilt Aiding
The V104s’ accelerometers (internal tilt sensors) are factory-calibrated and
enabled by default. This improves heading solution beyond the volume
associated with just a fixed antenna separation. This is because the V104s
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 3-2).
Figure 3-2: V104s’s tilt aiding
Gyro Aiding
The V104s’ 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
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