• | The ST90 system is in Normal mode, but TX Power is set to Off to prevent transmissions. |
• | The transducer is retracted to its upper position. |
• | Neither tools nor instruments are required. |
• | The water must be as deep as possible. Recommended minimum depth is 100 metres. |
• | There must be no other vessels in the vicinity. |
• | The vessel must lie still in the water. |
• | As much machinery as possible must be turned off. It is particularly important to turn off electrical motors, as well as cooling systems and hydraulic pumps that may cause electric noise. |
• | To prevent interference, all other hydroacoustic instruments must be turned off. |
1 | Make sure that you have sufficient water depth below the keel before you lower the transducer. |
2 | Lower the transducer to its bottom position. |
3 | Select the default settings.
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4 | At the bottom of the display presentation, select a suitable presentation mode, and activate the Horizontal view. |
5 | Make the following preparations.
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6 | Select Noise to open the page. |
7 | Select Start Noise Measurements.
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8 | Finish the test.
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For each transmit frequency (in kHz), write down the measured noise levels (in dB). | ||
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Frequency (kHz) | Maximum | Average |
14 | ||
19 | ||
24 |