POTENTIAL ACCURACY OF THE INTERFEROMETRIC SIDE-SCAN SONAR

Abstract

Currently there are a lot of investigations in the shelf zone of the coastal seas. These woks requires engineering surveys including the construction of the bottom topography. Interferometric side scan sonar is one of the most efficient system capable to solve such tasks. The ISSS is working by finding the phase difference between the two signals reflected from the same area on the bottom within one resolution element and received by two separated receiving antennas. Carrying out of correct interferometric phase difference is the main task for constructing bathymetry of the bottom surface. One of the main parameter of the interferometric sonar — the accuracy of measurement of the bottom relief. There are many factors affecting the accuracy. By selecting interferometric sensing mode and survey parameters at the stage of interferometric system development the impact of these factors may be minimized. Features of reflection and surface properties affect the final error through the interferometric phase difference. Therefore the main interest is the analysis of the error of the phase difference evaluation. In current paper this task is solving. In summary it is showed that certain choosing of parameters and modes of interferometric survey allows to obtain the interferometer measurement accuracy of real bottom topography close to the potential accuracy. The optimal baseline has been determined on the criterion of minimum standard deviation assessment of bottom topography. Also investigated the possible decorrelation of reflected signals due to the bottom surface roughness. The results showed that the baseline increasing is limited by decorrelation signals because of receive antennas spacing. Reducing baseline leads to the loss of sonar sensitivity due to the bottom relief roughness.