Robotics @ Maryland's ( http://ram.umd.edu ) Autonomous Underwater Vehicle (AUV) Tortuga 2 successfully homes in on an acoustic pinger. This is in the Space Systems Lab's ( http://ssl.umd.edu ) Neutral Buoyancy Research facility.
Tortuga 2 uses its four hydrophones in a large baseline configuration to determine the vector between it and the pinger. The hydrophones are on a generous loan by the Naval Surface Warfare Center, Carderock Division ( http://www.dt.navy.mil ). The signals are read and buffered by a Xilinx FPGA, processed by an Analog Device Blackfin DSP and then relayed to the AI running on the main computer.
This is the culmination of the a year and half of continuous work by the many members of our Sonar team. They went through three different board configurations and code bases until they hit upon the successful combination.