Prerequisites
The CS90 is installed as specified in this manual. The vessel is at sea. The CS90 is turned on, and it is working normally. Neither tools nor instruments are required. In order to do this test, the ship must be "silent".
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The water must be as deep as possible. Recommended minimum depth is 100 metres. |
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There must be no other vessels in the vicinity. |
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The vessel must lie still in the water. |
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As much machinery as possible must be switched off. It is particularly important to switch off electrical motors, as well as cooling systems and hydraulic pumps that may cause
electric noise. |
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To prevent interference, all other hydroacoustic instruments must be switched off. |
This test must be considered as indicative. With the vessel in port, the environmental conditions are not satisfactory. In the shallow waters of the port, noise from other vessels, dockyard workers or machinery will cause unreliable test results. If you do this tests in a busy harbour, or with noise sources present, the sensitive receivers will detect all the noise in
the nearby waters.
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 BITE dialog box.
NoteWithout external noise sources the level should not exceed ≤50 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 CS90 performance.
Procedure
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Make sure that you have sufficient water depth below the keel before you lower the transducer. |
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Lower the transducer to its bottom position. |
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3 |
Select the default settings.
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On the Main menu, select User Settings. |
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Observe the Factory Settings list. |
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Select the setting you wish to use. |
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Select Activate Selected Setting. |
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Select OK to apply your changes and close the User Settings dialog box. |
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Make the following preparations.
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Open the Operation menu.
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c |
Open the Active menu.
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Set Pulse Type to CW Medium. |
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Set Frequency to 70 kHz. |
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Set Vertical TX Sector to Narrow. |
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Set Noise Filter to Off. |
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Set the Bottom Filter Threshold to Off. |
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d |
Open the Setup menu.
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Select BITE to open the BITE (Built-In Test Equipment) dialog box. |
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Select Noise to open the page. |
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Select Start Noise Measurements.
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Observe the noise curve. |
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Read the maximum and average noise values. |
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Repeat for selected frequencies. |
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Record the frequencies and the measured values in the result table. |
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Hoist the transducer back up to its upper position. |
Result
For each transmit frequency (in kHz), write down the measured noise levels (in dB). |
Frequency |
Maximum |
Average |
70 kHz |
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85 kHz |
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90 kHz |
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