Experimental Implementation of an Echo Repeater for Continuous Active Sonar

The 2013 Target and Reverberation Experiment (TREX13) sea trial was held just off the coast of Panama City, FL, USA, in May 2013. One of Defence Research and Development Canada's primary objectives was comparing the performance of continuous active sonar (CAS) and pulsed active sonar (PAS) in shallow water, where reverberation and clutter challenge sonar systems. The only option for a moving target during the trial was an echo repeater towed from a ship; however, this posed a serious challenge because before the trial there were no known echo repeater solutions that were compatible with CAS. Existing echo repeaters required short-duration waveforms as used in PAS, and even then they introduced range errors that caused a mismatch in reverberation background and made localization problematic. This paper presents three echo repeater techniques developed for TREX13 and tested on Canadian Forces Auxiliary research vessel CFAV Quest during the trial. Experimental results presented in this paper demonstrate detection of the echo repeater by a monostatic CAS system on R/V Hugh R Sharp.