Challenges of visualizing the seafloor with modern sonar system

Aperture synthesis enables a high azimuth resolution from a physically small array. The technique has been highly successful in radio astronomy, satellite and aircraft borne radar. However the use of this technique has been limited to sonar because of difficulties of maintaining a stable track under water and problems of under-sampling of the aperture arising from the relatively slow velocity of acoustic waves. This paper describes the application of the synthetic aperture technique to sonar, highlighting some of these difficulties and possible means of overcoming them. Geometry is developed to measure the height of objects and to produce 3-D image.