Receiving and transmitting acoustic systems for AUV/gliders

Abstract

NURC in the past years have focused its research on the use of AUV and more recently on gliders and is now developing littoral autonomous sensing networks based onthose sensors to perform missions such as mine warfare, anti-submarine warfare, marinemammals risk mitigation and Rapid Environmental Assessment. For the differentmissions, new acoustic sensors, much smaller in size and having lower cost and lowerpower consumption are needed to be developed. The purpose of this paper is to present the work NURC started to do in that field since 2007. For example, in August 2007,NURC began to design and build a new thin High-frequency (up to 20 kHz) nested towedarray (31 mm diameter) for ASW purposes. Array data analysis of at sea experiments willbe shown to demonstrate that both AUV self noise as well as flow noise were not an issue whatever the tow speed and did not alter with the performance of the array. Based onthose results, NURC decided in 2008 to investigate the use of thinner diameter arrays,very thin line arrays, which could be used with small size AUVs and/or gliders as with reduced weight and drag. A very thin line 12 mm diameter array prototype has been builtin order to assess flow noise performance and also for exploring Linear Noise Power Averaging as a technique for suppressing flow noise on small diameter towed arrays.Then, the paper will describe the current development of a very high frequency (up to 160kHz) tetrahedral array for a glider that will allow detection and accurate localization of marine mammals. Eventually, the paper will describe the current development and thefirst results of a towed transmitter that will be towed by a NURC AUV to perform both bottom characterization and ASW missions.