Defining the installation parameters for the motion reference unit (MRU)
The physical location of the motion reference unit (MRU) relative to the transducer is required to allow the CS90 to adjust for roll and pitch as accurately as possible. This task is only applicable is you are using an external motion reference unit on your CS90.
Prerequisites
The CS90 is installed as specified in this manual.
•  The CS90 is turned on, and it is working normally.
•  The CS90 is in Normal mode, but TX Power is set to Off to prevent transmission.
•  The transducer is retracted to its upper position.
•  The vessel is berthed or at sea.
Neither tools nor instruments are required.
Caution
You must never set the CS90 to "ping" unless the transducer is submerged in water. The transducer may be damaged if it transmits in open air.
For accurate location of the motion reference unit (MRU), you need the detailed vessel drawings. The information about the installation angles must be retrieved from the reports provided by the personnel that installed the equipment.
Context
The information from a motion reference unit (MRU) (normally heave, roll and pitch information) is imported into the CS90 to increase the accuracy of the echo data. The CS90 is provided with a built-in motion sensor. It is placed inside the Motor Control Unit. For improved operational accuracy, an external motion reference unit (MRU) may be used. The motion reference unit (MRU) measures the roll and pitch motions of the vessel. Some sensor models also measure heave.
On the MRU page, you must define the physical location of the motion reference unit related to the reference point you created on the Ship page. The rotation around the X, Y and Z axis is used to compensate for misalignments made during the physical installation of the motion reference unit. Such misalignments occur if the sensor is not placed in parallel with the vessel’s horizontal and/or vertical planes. The required accuracy of the offset and rotation angles depends on the accuracy requirement for the CS90 data.
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A Rotation around the x-axis: In the positive horizontal direction (forward), a positive rotation is clockwise.
B Rotation around the y-axis: In the positive horizontal direction (starboard), a positive rotation is clockwise.
C Rotation around the z-axis: In the positive vertical direction (down), a positive rotation is clockwise.
D Reference point (Ship Origin)
Procedure
1 Open the Setup menu.
2 On the Setup menu, select Installation.
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Observe that the Installation dialog box opens. This dialog box contains a number of pages selected from the menu on the left side.
3 On the left side of the Installation dialog box, select the small white triangle next to Installation Parameters.
Observe that a menu opens with access to all the individual pages.
4 Select MRU to open the page.
5 From the vessel drawings, extract the relevant offset information, and insert those values.
Do this as accurately as possible.
6 From the information provided by the personnel installing the motion sensor, obtain the relevant rotation information. Insert the values.
Do this as accurately as possible.
7 At the bottom of the page, select Apply to save your settings.
8 Continue your work in the Installation dialog box, or select OK to close it.