Context
This task allows you to check the noise conditions. To measure the noise level, observe the value presented on the Noise page in the Diagnostics dialog box.
The noise must be measured with the sonar beam directed vertically from the transducer face. This is easy on an omni-sonar by setting both bearing and tilt to 0 (zero) degrees. The transducer on the SN90 system may however mounted on the port or starboard side of the vessel, and with a fixed tilt. Since the bearing and tilt choices on the menu are relative to the vessel heading, you must compensate for the installation
angles.
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You must always set the tilt to the same value as Rotation around Y. Check the installation parameters. The value for Rotation around Y is referenced to the default position, which is pointing straight down. To find the correct tilt, subtract the shown value from 90. For example, if Rotation around Y is set to 75 degrees, set Tilt to (90-75) 15 degrees.
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To choose the correct bearing, observe the Rotation around Z value. Check the installation parameters. Set Bearing to the same value as Rotation around Z. For example, if the transducer is mounted on the starboard side of the vessel with Rotation around Z set to 45 degrees, set Bearing to 45 degrees too. If the transducer is mounted on the port side of the vessel with Rotation around Z set to -55 degrees, set Bearing to -55 degrees too.
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NoteWithout external noise sources the level should not exceed 46 dB. If this level is exceeded in any direction you must locate the noise source(s). If the noise originates on your own vessel we strongly suggest that relevant actions are taken to reduce the noise and thus
increase the performance of the SN90 system.
A hull unit may be provided as an option. It allows you to lower and hoist the transducer.