Kongsberg Simrad ST90, Reference Manual

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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
To measure the noise, observe the noise values provided on the
Noise
page in the
Diagnostics
dialog box. Since the noise will vary with each ping, you must make five measurements
for each vessel speed, and then calculate the average noise.
Tip
If you record all the raw data during the noise test, you can repeat the test later using
the replay file.
You may wish to make the noise/speed curve under realistic conditions. This means that
all relevant vessels systems are in normal use. If you experience very high noise levels,
you may wish to repeat the test with "silent ship" settings. To isolate noise sources, turn
individual vessel systems off, and check for any changes in the noise level.
Note
When the transducer is fully lowered, the speed of the vessel must not exceed the maximum
speed permitted for the hull unit. This maximum speed depends on the physical size of the
transducer, the mechanical construction of the hull unit, and how far down the transducer
has been lowered. The
System Protection
page allows you to define a limit that triggers an
alarm if the maximum speed is exceeded. The
System Protection
page is located in the
Installation
dialog box.
Illustration:
Read the noise value from the noise circle. Use the
mean value of the readouts at 0 degrees (straight up).
Procedure
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 If necessary, establish a separate communication
line with the bridge to verify the vessel speed
during the test.
4 Make the following preparations.
a At the bottom of the display presentation, select Bow Up presentation mode, and
activate the Horizontal view.
Maintenance procedures