Kongsberg Simrad ST90, Reference Manual

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Related topics
Maintenance procedures, page 186
Testing the noise conditions and the sonar functionality, page 254
Transducer page, page 549
Measuring the noise in passive mode
Low noise is a key factor for high quality and reliable measurements. The performance of
the ST90 system will always be limited by different noise sources. A high noise level will
mask the echoes and make them difficult to read and interpret. The noise is measured while
the ST90 system operates in
Passive mode with the transmit pulses disabled.
Prerequisites
The ST90 system is turned on and operates normally.
• 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.
In order to do this test, the ship must be "silent".
• 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.
Note
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
Diagnostics
dialog box.
Simrad ST90 Reference Manual