New acoustic systems for AUV tracking, communications, and noise measurement at NSWCCD-ARD, Lake Pend Oreille, Idaho

Abstract

This paper describes a newly developed acoustic system for AUV tracking and communications at the Naval Surface Warfare Center (NSWC), Acoustic Research Detachment (ARD) in Bayview, Idaho. This acoustic tracking and communications system (ATACS) has unique capabilities and is highly versatile to support a variety of AUV tests. ATACS software and hardware create a turn-key system which could be replicated and deployed in a wide variety of ocean or fresh-water environments. The system is currently supporting large scale vehicle (LSV) model experiments for NAVSEA sponsors but has capabilities that can support testing such as verification of guidance systems and operation of constellations of multiple AUVs. The system can be configured to simultaneously track and communicate with a large number of independent AUVs, each transmitting a unique identifier code. Global Positioning System (GPS) clocks are distributed to analog-to-digital (A/D) converters throughout the system to provide global synchronization of sampling. Calibration of system timing characteristics allow precise system timing and ranging accuracy. Software-based ranging receiver algorithms are highly flexible and support both coherent and non-coherent ping types. The system can receive pinger frequencies between 10 kHz and 120 kHz and effectively transmit between 25 kHz and 120 kHz. Real-time detection software runs on a VME-based multi-processor system. Detected signals are passed to a host processor for precise timing estimates and telemetry demodulation. Range and telemetry information is then broadcast across the Ethernet to various client applications such as vehicle tracking and control, beamsteering, etc. This instrumented test range covers over 2 square miles with a lake depth of 1100 feet. The effective tracking area extends over 10 square miles. Six bottom-mounted transceiver units provide bi-directional communications and ranging with AUVs. Each transceiver unit is buoyed 100 feet off the lake bottom and contains separate broadband source and hydrophone elements.