Mine Detection Using Swath Bathymetric Sonars: Tools and Techniques

Swath bathymetric sonars such as multibeam echosounders and interferometric sidescan sonars are used primarily to produce bathymetric products such as charts and 3D modelled surfaces. The latest generations of these sonars have yet to realize their full potentials when it comes to detecting small objects such as mine like objects. This paper will first review the characteristics and capabilities of interferometric sidescan sonars and multibeam echosounders in order to highlight their strengths and weaknesses with respect to small object detection, and secondly, data from actual field surveys using each of each of these sonars will be examined in order to illustrate their small object detection efficacy. Next, this paper will present recommended techniques to optimize the probability of detection using each of these systems. These techniques include pre-survey preparations, survey execution, and post processing techniques such as mosaicking, coregistered imagery with bathymetry, and temporal imagery comparison. Finally conceptual 2D and 3D “Gapless” sidescan mine hunting sonars will be introduced, based on currently available technology, in order to illustrate that significant improvements in the Mine Hunting process are available. I. Introduction Naval Mine Counter Measures (MCM), more specifically Mine Hunting (MH), have failed to capitalize on some of the dramatic technological advances that seafloor mapping sonars have achieved in the last five to ten years. This failure has kept the process of running sidescan sonar surveys inefficient, wasting the time of both personnel and platform resources. The reasons for this oversight are varied, but one predominant factor is the very nature of the sonars themselves. The advanced capabilities and sophistication of modern seafloor mapping sonars has resulted in the need for highly trained and specialized operators, normally hydrographers, which is incompatible with the modern Mine Warfare (MW) personnel (operator) model. Although today’s sailors are motivated and intelligent, the amount of time and resources required to make an operator proficient on modern seafloor mapping sonars is measured in years which, by far, exceeds the time a specific operator is usually performing the MH function. In order for new, more capable technology to be successfully assimilated and fully exploited in a MH role, the HumanMachine Interface (HMI) must be straightforward and intuitive.