Konsberg EM 124, Installation Manual

Page: 135 / 212

443140/A
135
5 Verify that the mounting frame is in plane within the given tolerances.
6 Repeat the procedure until the tolerances are met
Related topics
Dimensional survey accuracy requirements, page 155
Alignment specifications, page 157
Calibration
During the sea trials, calibration surveys are required as described in the EM 124 end
user documentation.
In order to check and verify the performance of the EM 124 system, we strongly
recommend that calibration surveys are done at regular intervals, or prior to any large
survey.
The calibration process is described in detail in the Seafloor Information System (SIS)
Operator Manual.
Note
Calibration must be taken seriously. The final verification of correct installation can
only be done during calibration at sea. Installation and operational parameters that
do not meet the accuracy requirements may lead to incorrect data. To achieve the best
results, the calibration must be planned and done carefully.
Vessel coordinate system
The vessel coordinate system is established to define the relative physical locations
of systems and sensors.
When you have several different sensors and transducers on your vessel, and you wish
each of them to provide accurate data, you need to know their relative physical positions.
The antenna of a position sensor is typically mounted high above the superstructure,
while a motion sensor is often located close to the vessel’s centre of gravity. Both
of these are physically positioned far away from the transducer on a depth sensor,
which may be located closer to the bow. Very often, the information from one sensor
depends on data from an other. It is then important that the relevant measurements are
compensated for these relative distances.
Reference points must be established on the vessel at selected positions. These are
needed during measurements of the sensor positions. Visual markings at these positions
should be prepared and noted on the vessel drawings with
X , Y and Z coordinates in the
vessel coordinate system.
Dimensional surveying and alignment