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Simrad NSO Series Simrad Echo Sounder
Simrad Transducers & Accessories

While you view and interact with the display, your sonar module generates and processes sonar signals. These signals are broadcast into the water column and their echoes received by one or more transducers, each designed to work with a specific sonar technology and frequency.

Built-in Sonar

Some Simrad multifunction displays include a built-in sonar module, allowing compatible transducers to be connected directly to the display.

External Modules

Displays without built-in sonar features require an external sonar module, such as the Simrad SonarHub™ Sounder Module or BSM-3 Broadband Sounder. These modules connect to your display by Ethernet, and provide ports for one or more transducers.

Sonar Technology By Multi-function Display

NSS7 evo2
NSS9 evo2
NSS12 evo2
NSS16 evo2
NSS7m evo2
NSS9m evo2
NSO evo2
Broadband Sonar Built-in SonarHub™ or
BSM-3 module required
StructureScan® HD Imaging SonarHub™ or
StructureScan® 3D
module required
Built in
(DownScan only)
ForwardScan® Sonar SonarHub™ module
StructureScan® 3D Imaging StructureScan® 3D module required N/A

Sonar Technology by Module

SonarHub™ Sounder Module BSM-3 Broadband Sounder StructureScan® 3D Module
Broadband Sonar Yes Yes No
CHIRP Sonar Yes Yes (Dual-Channel) No
StructureScan® HD Imaging Yes No Yes
ForwardScan® Sonar Yes No No
StructureScan® 3D Imaging No No Yes

A quality echosounder is one of the most important pieces of technology any vessel should be equipped with.

Today’s recreational boaters have access to a fantastic selection of sonar technologies, each enabling a different underwater view. Whether you want to find fish, avoid running aground, or explore submerged structure with a stunning 3D view, understanding the available technologies helps you to make the right buying decisions when you’re ready to outfit your boat.

StructureScan® 3D Imaging

The latest in Simrad sonar technology, StructureScan 3D imaging scans underwater terrain and fish-holding structure to create a high-resolution, three-dimensional view beneath the water. As well as making it faster than ever to locate structures and changes in bottom layout, 3D imaging makes it possible to examine those features in detail without venturing beneath the water.

The view offered by StructureScan 3D is like a virtual underwater camera and show where features lie in relation to your vessel. You can also choose to pan, tilt and rotate the virtual camera manually in ScanTrack™ control mode, to explore your surroundings from any angle you choose.

StructureScan® HD Imaging

StructureScan HD combines high-frequency DownScan and SideScan sonar imaging technologies to create a picture-like view beneath the water, great for finding submerged structure and changes in bottom layout. By providing a panoramic view out to the side of your boat, StructureScan greatly reduces the time it takes to find fish-holding structure, promising anchorages, and other underwater features of interest.

In addition to StructureScan’s top-down perspective, DownScan overlay combines downward-looking imagery with the output from your CHIRP sonar, painting structure in striking detail while reliably picking out individual fish targets. StructureMap overlays SideScan imagery on your display’s chart page, offering a detailed view of submerged structure as it relates to your position.

The specialised StructureScan HD transducer offers selectable 455 kHz operation for maximum imaging range, and 800 kHz for maximum imaging resolution. A dedicated StructureScan port is included on SonarHub™ Sounder Modules, and on NSS evo2 displays with built-in sonar.


CHIRP sonar is a powerful bottom-tracking and fish-finding tool. By continuously sweeping through a range of frequencies, CHIRP exceeds many common limitations of single-frequency broadband sonar. While it produces the same side-on echosounder view, CHIRP offers substantially less noise and greater target separation – for example, the ability to discern individual baitfish within a school, or to see multiple closely-spaced game fish that may appear as one target on a broadband sounder.

As with broadband sonar, CHIRP transducers are available in a range of frequencies to suit different depths and applications. Simrad SonarHub™ modules and NSS evo2 displays are also capable of delivering CHIRP functionality using conventional single-frequency transducers, allowing easy and cost-effective retrofit of CHIRP technology into vessels currently wired for broadband sonar.

  • Low CHIRP
    Accurately track the bottom in deep water (compatible with 50 kHz single-frequency transducers)
  • Medium CHIRP
    Greater resolution than Low CHIRP, with minimal loss of depth penetration (compatible with 83 kHz single-frequency transducers)
  • High CHIRP
    High resolution, for the greatest image quality in shallow water (compatible with 200 kHz single-frequency transducers)

Dual-channel CHIRP transducers, exclusively compatible with the Simrad BSM-3 Broadband Sounder module, are able to sweep two frequency ranges simultaneously. For example, this offers the ability to scan the upper water column in high resolution with High CHIRP, while at the same time employing Low CHIRP for superior bottom tracking.

Simrad Broadband Sonar (50/83/200 kHz)

This essential sonar technology is great for tracking depth, finding schools of baitfish, and displaying predator fish in the water column directly beneath your boat. Broadband sonar offers a traditional side-on echosounder view, with ‘fish arches’ formed as fish pass through the downward-facing sonar beam.

Broadband sonar relies on sonar 'pings' and echoes on a single frequency, dictated by your choice of transducer. Most transducers are designed to operate at one of the frequencies below, while 'dual frequency' transducers let you select either of two supported frequencies to best suit your current situation.

Available frequencies include:

  • 50 kHz (Low Frequency)
    High power, ideal for bottom tracking in deep water
  • 83 kHz (Medium Frequency)
    Wide coverage area, useful when searching for structure or tracking bait in shallower water
  • 200 kHz (High Frequency)
    High resolution, for the greatest image quality and easy fish tracking in shallow water

The Simrad Broadband Advantage
The more power a single-frequency echosounder can put behind its ping, the stronger the echoes received from the bottom and other submerged targets. That should mean greater depth penetration, and better target detection. However, more power also means more noise in the image – making it harder for you to identify targets on screen. Simrad Broadband sonar uses less power, but varies its ping in a way that actually puts more energy into the water overall. This means greater image quality, with less image noise than conventional single-frequency sounders.

ForwardScan® Sonar

This forward-looking sonar provides a clear two-dimensional image of the bottom in front of your vessel, allowing you to navigate shallow or poorly-charted waters with a greater degree of safety.

ForwardScan offers:

  • A maximum forward view of 8X your current depth
    e.g. at 3m (10ft) depth, see up to 24m (80ft) ahead
  • A nominal forward view of 4-5X your current depth
    e.g. At 3m (10ft) depth, see 12-15m (40-50ft) ahead

ForwardScan output can be viewed as a solid 2D rendering of the bottom ahead of your vessel in sonar view, or integrated with the heading line on your display’s navigation page as colour-coded segments representing deep, medium and shallow water. This provides constant awareness of the depth ahead, and allows easy comparison of measured and charted depths.

The specialised ForwardScan transducer operates at 180 kHz to reduce interference with traditional 200kHz echosounders. It connects to the StructureScan port on Simrad NSS evo2 displays, and on SonarHub™ sounder modules. In order to use both StructureScan and ForwardScan sonar simultaneously, two sonar modules are required; on NSS evo2 systems with built-on sonar, this means just one external sonar module, plus the built-in StructureScan port.