Time-Frequency Detection: Application to Sub-Bottom SONAR

November 2000

introduction specifications

Introduction

The ATLAS Parasound system is a parametric high-resolution sub-bottom profiling sonar. A common problem with high-resolution marine acoustic systems in general is the moving platform. Roll-, pitch- and heave-compensation have to be accurate down to the actual range-resolution of the system. In some cases the capability of compensating systems may be insufficient.

An example of an echo-record showing the effect of these deficiencies is shown in figure 1. The range-errors are quite detrimental in this particular case, the lack in coherency of later returns makes interpretation a difficult task. Additionally the recordings show crosstalk from a second acoustic system on board the vessel (a multi-beam bathymetry sounder), which has leaked through the bandpass filter.

In order to re-detect first breaks in the signals for subsequent alignment, a simple peak-detector will most likely fail due to this crosstalk.