Adjusting the stabilization offsets for the motion sensor
The SY50 system is provided with a built-in motion sensor to provide electronic stabilization of the sonar beams. It is located inside the Power Supply Unit. It is very important that the motion sensor is set correctly with stabilization offset values that are adapted to the physical installation angles of the hull unit. To align an external motion sensor to the internal sensor, you may need to adjust the stabilization offset values.
Prerequisites
Note
Before you do this task, you must adjust the installation offset of the motion sensor.
The SY50 system has been set up with its hardware units connected as specified in the Installation Manual.
•  The external motion sensor is connected to the SY50 system.
•  The MRC application is installed on the Processor Unit.
•  The SY50 system is turned on and operates normally.
•  The vessel is berthed.
The following tool is required:
•  Digital level
Note
We recommend that you do this task in calm sea without any vessel movements.
Context
It is very important that the motion sensor is set correctly with stabilization offset values that are adapted to the physical installation angles of the hull unit. Even a small offset error can give you very inccurate readings. The internal motion sensor is located inside the Power Supply Unit. Because of this, the risk of stabilization offset misalignment is present.
The two screen captures below illustrate how the SY50 system can provide inaccurate data if the stabilization offset is misaligned. In both examples, the tilt is set to approximately 24 degrees, and you are looking at the echoes from a flat bottom at a very short range. The first example is made without any offset errors, and the echoes from the bottom are evenly distributed in the circle. On the second screen capture, a 3 degrees roll offset error causes the echoes to be "distorted". This error will of course be more visible on longer ranges.
Image
Image
Note
Do not confuse stabilization offset with installation offset. The installation offset values describe the physical location and orientation of an item, and how this location is related to the vessel's coordinate system. The stabilization offset values describe any misalignments related to the measurements a sensor make.
Procedure
1 Select a very short range.
2 Make sure that the installation parameters for the internal motion sensor (offset and rotation offsets) are correct.
3 Open the Display menu.
a Select Display Options.
b Select General to open the page.
c In the Top Bar list, enable Roll and Pitch.
d On the top bar, read the roll and pitch values.
e Write down the values.
f Select OK to save the selected settings and close the dialog box.
4 Place the digital level on the mounting flange.
Image
a Measure the roll and pitch angles.
b Write down the values.
c Compare the measured values with the values provided on the top bar.
Adjustments are required if the measured values do not match.
5 If necessary: Adjust the stabilization offsets.
a Open the Setup menu.
b Open the Stabilization function.
c Adjust the Roll Offset and Pitch Offset settings.
Select [] on the left side to decrease the value, or select [+] on the right side to increase.
For improved operational accuracy, an external motion reference unit (MRU) can be used. To align an external motion sensor to the internal sensor, you may need to adjust the stabilization offset values. The external motion sensor is connected to the SY50 system.
6 Make sure that the installation parameters for the external motion sensor (offset and rotation offsets) are correct.
7 Open the Setup menu.
a On the Setup menu, select Installation.
b On the left side of the Installation dialog box, select Motion Reference Unit.
c Select COMx to connect to the external motion sensor.
("COMx" is the serial port to which the motion sensor is connected.)
d Select which NMEA sentence (datagram) you want to use.
e Select the baud rate.
f Select Apply and then Close to save your choice and close the Installation dialog box.
8 On the top bar, read the roll and pitch values.
a Compare the new pitch and roll values with the values from the internal motion sensor.
b If necessary: Adjust the stabilization offsets.