NICOP - The Effect of Ocean Surface Waves on Long Duration, Wide Bandwidth Waveforms in High Duty Cycle Sonars
Abstract
: Military sonars must detect, localize, classify, and track submarine threats from distances safely outside their circle of attack."" High Duty Cycle (HDC) Sonars have duty cycles approaching 100% which enables near-continuous tracking. Furthermore, the wide band"width pulses these systems are capable of transmitting can lead to improved target classification. Because these systems show great" potential, HDC has become a high profile topic as the US integrates this technology into its fleet. HDC Sonar offers the opportunit"y to tune sonars to optimize the conflicting requirements of faster update rates for better tracking (more sub-bands but lower SNR p"er sub-band), with higher detection thresholds to reduce false alarm rates (fewer sub-bands but higher SNR per sub-band). HDC offers"" exciting possibilities for enhancements to anti-submarine warfare (ASW) systems; however, performance in the littorals for pulses o"f long duration and/or wide bandwidth is heavily dependent on maintaining signal coherence as the acoustic wave propagates through t"he water column, and reflects and scatters from the ocean boundaries. Results from the TREX13 experiment show that the coherent (re"flected) and incoherent (scattered) acoustic intensity are functions of the mean-squared surface roughness and the two-dimensional o"cean roughness spectrum. Moreover, that work demonstrated that state-of-the-art propagation and surface scattering models are not eq""uipped to handle the longer durations and wider bandwidths of HDC waveforms. Although extremely instructive, the TREX13 measurements" were constrained to relatively calm conditions and extremely shallow water because the equipment was deployed from a moored vessel." Because signal de-correlation in higher sea states has not been scientifically measured or modeled, it makes performance prediction" extremely difficult. The goal of the proposed work is to extend the knowledge acquired during TREX13 by examining the coherence of" shallow water channels for HDC pulses, as a function of pulse duration and bandwidth, under varying surface roughness conditions."" As well as increasing the research community~s limited knowledge base on the subject, it will help anticipate future questions pos"ed by the operational community as HDC is employed in the littorals. The results of this research will be presented at scientific conferences and published in peer reviewed journals.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 07, 2017
- Source ID
- N629091712090
Entities
People
- Paul C. Hines
Organizations
- Dalhousie University
- Office of Naval Research
- United States Navy