Simrad HS80/MX575C, User Manual

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Operation | HS80/MX575C User Manual
Supplemental sensors
The HS80/MX575C has three supplemental sensors (gyro and two tilt sensors) that are
integrated into the unit’s main PCB. The supplemental sensors are enabled by default. You
can enable/disable the gyro and both tilt sensors (you cannot enable/disable each tilt sensor
separately).
The sensors act to reduce the RTK search volume, which improves heading startup and re-
acquisition times. This improves the reliability and accuracy of selecting the correct heading
solution by eliminating other possible, erroneous solutions.
Sensor operation summary
Feature Normal Operation Coasting (no GPS)
Heading GPS Gyro
Heave GPS None
Pitch GPS Inertial tilt sensor
Roll Inertial sensor Inertial tilt sensor
Tilt aiding
The HS80/MX575C’s accelerometers (internal tilt sensors) are factory calibrated and enabled
by default. This constrains the RTK heading solution beyond the volume associated with
just a fixed antenna separation. This is because the HS80/MX575C 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 instances of incorrect headings as well as startup and
reacquisition times (see Figure 3-2).
Tilt angle
Figure 3-2: HS80/MX575C’s tilt aiding