A versatile system-independent echo-repeater system

To support a host of underwater acoustic measurements, a low-cost, system-independent echo-repeater system has been developed at the Naval Research Laboratory. This system (i.e. echo-repeater software, computer, data acquisition (DAQ) hardware, signal conditioning, etc.) was required to be: (1) capable of handling a wide frequency range ( up to 10+ kHz ); (2) capable of being plugged into a variety of power amplifiers and "wet-end" systems ("wet-end" being defined as the transducer and/or hydrophone combinations that are deployed into the ocean); (3) flexible both in signal capture and signal transmission; (4) capable of transmitting complex waveform schedules; (5) low cost; and (6) easy to maintain and upgrade. Scientific research areas this echo-repeater system supports include, but are not limited to, target classification/simulation, time reversal, transmission loss and time spread, and waveguide characterization. This paper describes this modular system and how it has been used to support these diverse research applications