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Simrad ST90
On some vessels, additional transducer protection is required. One example is vessels
working in arctic conditions. It is important for them to prevent ice from damaging
the transducer. A gate valve is then added to the hull unit installation. By means of a
mechanical construction it shuts off the bottom of the installation trunk when the ST90
system is not used.
For more information, refer to the end-user documentation provided by the manufacturer.
Important
The hull unit gantry must be secured to the bulkhead by means of mechanical support
brackets. The dimensions and strength of the support brackets must be adequate to
prevent vortex induced vibrations. This is an invariable requirement to ensure the safety
of the ST90 system and the vessel.
We recommend that support brackets are placed pointing at minimum three directions
with approximately 120 degrees between them.
The mechanical support brackets must be designed and manufactured by the installation
shipyard to fit the complete installation in the sonar room. All calculations made to
support the design must meet the applicable safety requirements, and apply to the
physical properties of the complete installation.
Related topics
Simrad ST90, page 7
System units, page 13
Transducer description
The cylindrical transducer allows the sonar beam to provide a full 360 degrees coverage
of the water volume.
The transducer converts the electric energy generated by the transmitter circuitry to
physical vibrations. These vibrations alter the water pressure, and create an acoustic
pulse that is sent into the water. The acoustic signal is transmitted as a beam. The
duration of the acoustic pulse, as well as its frequency and shape, are controlled by the
system software. The direction and opening angle of the beam is controlled by the
transmitter circuitry and the physical properties of the transducer. After the transmission,
the transducer works as a "microphone". It converts the water pressure created by the
acoustic echoes to electric energy. These weak echo signals are sent to the amplifiers
in the receiver circuitry.
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110-0035138/A
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