System description

The Simrad ST90 is a low-frequency fish-finding sonar with 360-degree coverage and long range. The ST90 system is designed for medium and large sized fishing vessels.

If high performance is your number 1 criteria when choosing a sonar; such as long range, high resolution, narrow beams and high source levels, this is your natural choice. We made no compromises during the design of the ST90 system. Our goal was simply to make the ultimate high performance fish finding sonar. With the ST90 system we use lower frequencies than the SX90 and SU90 sonars. In order to achieve this, a completely new transducer has been designed. Each element is larger than the previous SX90 and SU90 elements, but the number of elements is the same as the SU90. This allows for the same narrow beam, and ultimately a longer range. The ST90 system has been designed to search with very long ranges in all weather and sea conditions. Whether it is heavy weather, hard bottom, open waters, weak targets - all echoes are handled by the ST90 system due to the fully stabilized and very narrow beams combined with the cutting edge signal processing.

The centre operational frequency is 19 kHz. You can select any operational frequency from 14 to 24 kHz.

The cylindrical multi-element transducer allows the omnidirectional sonar beams to be tilted electronically. This allows you to automatically track schools of fish, and to observe the whole water volume around the vessel.

The ST90 system offers a number of standard interface lines for communication with peripheral devices and sensors. Typical inputs are geographical information from a positioning system, vessel speed and current heading. By default, the ST90 system uses a built-in motion sensor. For improved operational accuracy, an external motion reference unit (MRU) can be connected.

The narrow beam opening angle and the high source level makes the ST90 system a very powerful and high resolution low frequency sonar. The narrow beams provided by the ST90 system give you several advantages.

  • They increase the range and resolution, and offer a vertical view with additional details and a clearer picture.
  • They make the ST90 system even more ideal when you need to search for fish close to the sea bottom, or close to the surface, at long ranges.
  • They provide a far better vertical view with less "bottom climbing" that what is seen on sonars with a wider beam.
  • The narrow beams also decrease the noise level.

The ST90 system offers the same user interface and operating software as our other sonars, echo sounders and catch monitoring systems. This enables easier and faster training of new users.

  • The echo presentations are optimised for multiple displays. Provided that you have connected additional displays to your Processor Unit, you can use the Docking Views function to take any sonar view and place it on a separate display. When you move a view to another display, it will automatically be scaled for the best possible result.
  • It is common for sonars to require many pings to build the various views in the echo presentation. On the ST90, all the sonar views in the presentation are built using the echoes from one single ping. This dramatically improves the update rate and provides better real-time information.
  • The ST90 system permits you to record real-time sonar situations. This allows you to replay complete sequences. The playback contains the exact same echo information, and can be used for mission history, training or troubleshooting purposes.

Great emphasis has been placed on an intuitive user interface and the best possible sonar presentations on a high resolution colour display.

The ST90 system is equipped with the celebrated signal processing software developed by Kongsberg Discovery. This includes Hyperbolic FM (HFM) transmissions. This pulse type is also known as "chirp". It ensures a clutter free picture with very high resolution in range. Signal processing and beamforming are performed in a fast digital signal processing system, using the full dynamic range of the signals.

The ST90 system software operates using the Microsoft® Windows® operating system.