POS MV V5 Installation and Operation Guide
Introduction
Copyright © Applanix Corporation, 2017
1-9
Figure 3: Heading Measurement with GAMS
After alignment, the IMU delivers measurements of multibeam transducer heading relative to true north.
These measurements possess the same accuracy as those of vessel heading defined in the paragraph
above.
Refer to the Theory of Operation description on page B-1 for a more complete description of GAMS,
together with an explanation of GNSS carrier phase differential position measurement, levelling,
gyrocompassing and the Kalman Filter.
Refer to the Lever Arm Distances, page 2-26, and the Antenna Baseline Vector
The antenna baseline vector is the vector describing distance from phase centre of primary antenna to
phase centre of secondary antenna in the vessel frame. If this vector can be determined accuractely
(error <= 5 mm) then the values can be entered into the GAMS parameter setup window and avoid
having to perform a GAMS calibration, which on a large vessel may not be practical or as accurate. If the
antenna baseline vector cannot be accurately determined and the vessel can perform dynamics sufficient
to achieve a good GAMS calibration then the baseline vector parameters can be left as zero.
Refer to the Lever Arm Distances, page 2-26, and the Antenna Baseline Vector
The antenna baseline vector is the vector describing distance from phase centre of primary antenna to
phase centre of secondary antenna in the vessel frame. If this vector can be determined accuractely
(error <= 5 mm) then the values can be entered into the GAMS parameter setup window and avoid
GPS derived heading
information
Rotation
Surveyed antenna
baseline vector
POS MV with GAMS
heading aiding
IMU begins levelling
and alignment
Rotation
IMU wrt reference
frame mounting
angles
Levelling
& alignment data
POS MV power-on
After levelling
& alignment
Kalman
Filter
GAMS
Heading aiding information in
IMU coordinate frame
Heading alignment
complete within
2 to 5 minutes
Heading
information
Rotation
Rotation
Ship frame wrt
reference frame
mounting angles
Sensor 1 (Sonar) wrt
reference frame
mounting angles
Vessel heading
accuracy = 0.02
degree
(0.03° for
WaveMaster)
Sonar heading
accuracy = 0.02
degree
(0.03° for
WaveMaster)