Test of an high data rate acoustic link in shallow water

The GESMA (Groupe d´Etudes Sous Marine de l´Atlantique) need to provide a high data rate acoustic communication link to a mine hunting AUV that will operate in shallow water. The estimated goal is between 20 and 30 kbits/s for a 1 km range. This should allow the AUV to transmit either many sensor status or sonar/video images to a surface ship behind. It thus involves coherent modulation transmission, and time-spatial equalization in reception. In order to evaluate which kind of receiver will best fit the objectives, an experiment was set up in September 1997. We recorded high signalling rates PSK in various shallow water areas. This paper presents the objective of the project, describes the experiments, and gives the first results obtained with two different receivers: a DFE multichannel combiner, and a joint beamformer and equalizer