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System diagram

The Simrad SX90 comprises a computer with an operating panel, a transceiver and a hull unit with the transducer.


(A) Display (the second display is optional)
(B) Processor Unit (computer)
(C) Operating Panel
(D) Transceiver Unit
(E) Hull Unit
(F) Hoist motor
(G) Motor Control Unit
(H) Transducer

The cables between the wheelhouse units and the SX90 Transceiver Unit in the sonar room must be dual high-quality Ethernet cables. These can be purchased locally or ordered from us.

Installation drawings

Outline dimension and production drawings are provided in PDF and DWG formats. Use the link to open the drawings page in a new window.

Processor Unit

The SX90 Processor Unit is a rugged and powerful computer. It is designed for long life in a demanding maritime environment. The Processor Unit contains the operational software and offers the user interface that allows you to control the SX90. Furthermore, it offers several serial and Ethernet lines for communication with external devices. The Processor Unit is normally mounted on the bridge.

The Processor Unit is designed for rugged maritime use. It has been customized by Kongsberg Maritime. Except for the fans, it contains no moving parts. The computer is based on a commercial design, but the software and hardware have been specified by Kongsberg Maritime to suit the SX90 requirements. The Processor Unit cabinet is placed on shock absorbers.

The Processor Unit is based on the Microsoft® Windows®10 operating system.

The computer offers multiple USB ports for use with future software upgrades. These USB ports also allow you to export screen captures from the SX90.

Operating Panel

The Operating Panel offers all necessary control functions for normal operation of the SX90.

The controls provided by the Operating Panel are arranged in logical functional groups. This offers you clear and easy operation with fast access to key functionality. The majority of the SX90 functions can be accessed using the trackball on the Operating Panel and the menu system shown in the SX90 presentation.

You can also use a standard computer mouse to control the SX90. The mouse can be connected to either the Operating Panel or directly to the Processor Unit.

A dedicated Ethernet cable is used to connect the Operating Panel to the Processor Unit.

If you have more than one sonar installed these can share the same Operating Panel. A dedicated button on the panel permits you to easily change which sonar to control.

Transceiver Unit

The SX90 Transceiver Unit is provided to transmit acoustic energy through water. This transmission and reception are commonly referred to as a ping. After each transmission, the transceiver receives the echoes from the targets in the water and/or the seabed. These echoes are filtered and amplified and then converted into digital format.

The Transceiver Unit is normally located in the sonar room. It is mounted on the bulkhead using powerful shock absorbers.

The Transceiver Unit controls the transmission and reception made by the 256 transmitters and 256 receiver channels. Eight identical transceiver boards are used. Two high capacity Ethernet cables connect the Processor Unit to the Transceiver Unit. Another high-quality Ethernet cable is used to connect the Transceiver Unit to the Motor Control Unit on the hull unit.

The Transceiver Unit is fitted with a commercial heat exchanger. The purpose of the heat exchanger is to provide a stable, clean and temperature controlled environment for the electronic circuitry inside the Transceiver Unit.


The cylindrical SX90 transducer allows the sonar beam to provide a full 360 degrees coverage of the water volume. The transducer is large and heavy. It contains 256 individual elements.

The transducer converts the electric energy generated by the Transceiver Unit 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 Transceiver Unit. The direction and the opening angle of the beam is controlled by the Transceiver Unit 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 Transceiver Unit.

The transducer is mounted at the bottom end of the hull unit's transducer shaft. This allows the transducer to be lowered into the water for operational use and retracted for protection when the SX90 is turned off. By lowering the transducer into the water, you may also be able to reduce the noise created by the laminar flow of water along the hull.

NOTE: The red protective coating is a vital part of the transducer. It is very important that neither this coating nor the internal parts of the transducer are damaged during the handling, installation or cleaning. Any holes and/or scratches in the transducer surface will allow water to penetrate the transducer. If a leak occurs, the transducer must be replaced.

A transducer must always be handled as a delicate instrument. Incorrect actions may damage the transducer beyond repair. A physical blow to the transducer face may easily damage one or more elements. Observe these transducer handling rules:

  • Do not activate the transducer when it is out of the water.
  • Do not handle the transducer roughly and avoid impacts.
  • Do not expose the transducer to direct sunlight or excessive heat.
  • Do not damage the outer protective skin of the transducer.
  • Do not use high-pressure water, sandblasting, metal tools or strong solvents to clean the transducer.
  • Do not step on the transducer cables.
  • Do not damage the transducer cables, and avoid exposure to sharp objects.

Hull unit

The hull unit provided with the SX90 is designed to lower the transducer down below the ship's hull when the SX90 shall be used. When the SX90 is switched off, the transducer is hoisted for protection. The SX90 Fish finding sonar can be provided with one of the following hull units.

Hull unit Lowering depth Transducer cable Maximum speed
SX92 1.2 m 4.6 m 25 knots
SX93 1.6 m 4.6 m 20 knots
SX95 1 m 4.6 m 12 knots

The hull unit is a large mechanical construction. It is mounted on the top of the installation trunk. The installation trunk penetrates the ship's hull and allows the transducer to be lowered into the sea. The hull unit is normally located in the forward part of the vessel. This location is recommended to avoid the noise from the propellers and the engine.

The purpose of the Motor Control Unit is to control the hoisting motor on the hull unit. When you make the appropriate commands on the CS90 sonar, the Motor Control Unit will start and stop the motor. It will also make sure that the motor rotates the correct way. The motion sensor for the built-in electronic stabilization of the sonar beams is provided.

To lower the transducer, press Down on the Operating Panel. To indicate transducer movement, the indicator lamp flashes, and an audible signal is sounded. When the bottom position has been reached, the indicator lamp is lit, and the audible signal stops.

To retract the transducer, press Up on the Operating Panel.

The transducer can also be lowered to any selected middle position. On the Operating Panel, press Middle.

In case of a power failure, the transducer can be raised or lowered manually using a hand crank.

If you forget to hoist the transducer before the sonar is turned off, the transducer is hoisted automatically before the power is disconnected. The transducer is also hoisted automatically if a serious malfunction occurs to the communication between the bridge and the hull unit.

Caution: If the transducer hits larger objects or bottom, the transducer shaft may be bent, or - in the worst case - it can be broken off. A broken transducer shaft will cause water leakage through the top of the shaft. If you suspect that the transducer shaft is seriously damaged with holes, do not retract the transducer to its upper position. To prevent serious damage to the vessel or the vessel stability, you must have a water pump and a warning system in the sonar room.