Mechanically scanning sonar
Mechanically scanning sonars transmit and receive an acoustic beam via a sonar head mounted on a step motor. This motor allows the head to rotate 360 degrees for full sonar coverage. They can be deployed via pole mount, tripods, or ROVs. Many scanning sonars have dual-frequency capabilities and various resolution options to choose from. This combination enables them to offer both (high resolution) short-range and (low resolution) long-range sonar options. Scanning sonars have relatively slow update rates as compared to multibeam sonars.
However, when mounted to a fixed platform, they produce highly detailed sonar images. They are an excellent choice for smaller localized search areas. While they can be used to search larger areas, the requirement of a stable platform leads to the continuous repositioning of the system. This is time-consuming and requires careful attention to detail to ensure no gaps in sonar coverage overlap.
When attached to a mobile platform such as an ROV, they may be limited to providing obstacle avoidance capabilities. As mentioned previously, the system produces its sonar image via a rotating sonar head. When mounted on a mobile platform such as an ROV, this rotation causes the sonar image to distort and can produce a blurred/smeared sonar image. This is due to the slow update rate of the step motor. However, if you were to keep the ROV stationary by hovering or sitting on the bottom, the system will start to produce a clearer image.
You can find details on our mechanically scanning sonar training programs on our Sonar Training page.