Single-Beam SONAR
Single-beam sounding is referred to as “traditional” SONAR. While single-beam systems have existed for over 50 years, confidence in the technology is often misplaced.
The transducer is customarily mounted in a vessel, and although the vessel may be equipped with a heave sensor, there is normally no way to measure the orientation of the transducer during operation.
The beam-width of most single beam sounders varies between 10 and 30 degrees. The method utilized in single broad-beam bottom detection relies on estimating the shortest slant range to the seafloor that is ensonified within the main lobe of the beam. As there is already an existing plus or minus 5 to 15 degree angular uncertainty (based upon the 10 to 30 degree beam-width), there is very little point in analyzing the vessel’s pitch and roll characteristics, as these are usually below this existing uncertainty.
Thus, the method for determining the minimum slant range provides an answer that is merely an estimate. While this method is reasonably adequate when the sea state is low and where the seafloor is reasonably flat, it has obvious limitations. Further, even in these “ideal” conditions, no information is gathered about the topography of the seafloor outside the SONAR beam footprint. This, in turn, leads to guesswork about what lies between survey lines.
