Interferometric angle estimation for bathymetry performance analysis

The quality of depth measurements used in either sonar or radar applications determines the confidence on the mapping accuracy. Several methods can be considered to determine this depth measurement, ranging from amplitude-based detection, interferometry, to complex signal-based detection, such as so-called high-resolution methods. This paper is devoted to the analysis of interferometry accuracy according to the nature of the recorded signal. Indeed, the level of fluctuation of the received signal depends on the remote-sensing application under consideration. In applications where both transmitter and receiver are linked with a direct path, e.g. underwater positioning applications or some underwater acoustic communication systems, neither a backscattering nor multipath effects increases the intrinsic fluctuating nature of signal. Conversely, in sonar bathymetry or radar earth-surface relief applications, the received signal suffers from reflection or backscattering effects, resulting in a more probable random behavior. Hence, the goal of this paper is first to investigate the behavior of two different signal models (stable and fluctuating targets), second to determine the associated signal fluctuation level, and finally, to intend to relate their interferometry accuracies. The different expressions of the interferometry accuracy will make it possible to adapt the accuracy computation of interferometry measurements to the application under consideration. Furthermore, a set of easy-to-use interferometry-accuracy expression will result from the statistical analysis, enabling simple topographic performance prediction.