System description
The SN90 is a directional high frequency fish finding sonar. Due to the high resolution and long range, the SN90 sonar has proven to be a very efficient tool for both trawlers and purse seiners.
Image
For purse seine applications, the transducer is mounted on the port or starboard side of the hull, facing the seine.
Image
The transducer’s protected position prevents damage from the purse wire, and still gives you full control while setting and retrieving the net. The SN90 allows you to run alongside a school of fish and observe, and you can analyse the school without passing over it. This is like using a horizontal mounted echo sounder, but with a lot more accuracy, and with dedicated software and presentation formats. Fish avoidance is minimized, and more accurate information about the fish in the school can be obtained. You can detect unwanted species, catch the correct size and estimate the volume of the school before setting the net.
In purse seine operations, the large frequency bandwidth makes the SN90 ideal for both mackerel and tuna, and even for herring.
Trawlers have for many years relied on high resolution echo sounders - such as the Simrad ES70 - to find and estimate their catch. The disadvantage with echo sounders is the fact that they look straight down.
Image
The SN90 offers the high resolution of an echo sounder, but also a large horizontal range that allows you to find fish - even close to the bottom - from a distance of several hundred meters. The high frequency bandwidth makes the SN90 ideal for species like pollock, cod and saith.
During the search phase, a forward looking SN90 is a very efficient tool for all trawlers. Since the transducer is placed in the vessel’s bow, the SN90 will not suffer from the acoustic noise generated by the hull, machinery and propellers.
The physical installation angle of the transducer must be determined based on the depth in the vessel’s normal fishing waters. Even with a fixed installation angle, the SN90 will serve well in other waters too due to the swath and tilt functionality.
Tip
A hull unit may be provided as an option. It allows you to lower and hoist the transducer.
SN92HPX, SN93HPX: A special version of the transducer housing is available for use on a hull unit. Two trawl hydrophones are added for use with a catch monitoring system. Both hydrophones point aft. The trawl hydrophone offers a 50 degrees horizontal beam and a 30 degrees vertical beam. This specific beam pattern is especially suited for trawling.The wide coverage area reduces the need for careful alignment. This provides optimal reception from sensors on a bottom or pelagic trawl.
The SN90 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 SN90, 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 SN90 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 SN90 system is equipped with the celebrated signal processing software developed by Kongsberg Maritime. 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. The signal processing and beamforming is performed in a fast digital signal processing system using the full dynamic range of the signals.
The SN90 system software operates using the Microsoft® Windows® operating system.