Kongsberg Simrad ES80, Руководство по установке, Страница: 186 / 312

184
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Placing each sensor in the vessel coordinate
system
Topics
Dimensional surveying, page 184
Surveying the transducer and the navigation sensors, page 185
Example procedure, page 186
Vessel coordinate system, page 189
Dimensional surveying
Several sensors are connected to the ES80 to make its operation as accurate as possible.
These sensors are physically located on different places on the vessel. Typical sensors
are those providing navigational information (heading, speed or geographical position) or
vessel movements in the sea (motion sensors).
In order to "move" these sensors to a common location on the vessel a vessel coordinate
system is defined. The relative location of each sensor is then measured and referenced to
this coordinate system. This is commonly referred to as dimensional surveying .
Why is this important?
When a sensor makes a measurement, the information is always related to the physical
position of the sensor. This introduces an error since this is not the physical location of
neither you nor the ES80. On small vessels, these measurement errors are often negligible.
On larger vessels, however, the distances between the sensors are greater, and the errors
can affect the accuracy of the ES80. The errors become extra noticeable when the vessel
moves in heavy seas.
Example
The antenna of a position sensor is typically mounted high above the
superstructure, while a motion sensor is 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.
If you have an echo sounder transducer located close to the bow, the measured
depth will change considerably when the bow is subjected to heave in heavy seas.
In order reduce the measurement errors you can do this:
• Install and use a motion reference unit (MRU) to detect the movements of the vessel.
Simrad ES80 Installation Manual