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Broadband Doppler-Sensitive Waveforms for Energy-Constrained Distributed Active Sonar Systems
Navy SBIR 2006.2 - Topic N06-161 ONR - Ms. Cathy Nodgaard - [email protected] Opens: June 14, 2006 - Closes: July 14, 2006 N06-161 TITLE: Broadband Doppler-Sensitive Waveforms for Energy-Constrained Distributed Active Sonar Systems TECHNOLOGY AREAS: Information Systems, Sensors ACQUISITION PROGRAM: PMA-264 Air Multi-static Program (ACAT III) OBJECTIVE: Develop and evaluate broadband Doppler-sensitive waveforms and innovative signal and information processing for detection, classification, and localization (DCL) of both high- and low-Doppler targets on multistatic ASW active sonar systems operating under energy constraints. DESCRIPTION: A distinct advantage of distributed or multistatic active sonar systems is the ability to detect, classify and localize targets in large areas of the search field that are moving with narrowband Doppler-sensitive waveforms. However, slowly moving targets and targets in regions of low radial velocity (i.e., low-Doppler targets) require the transmission of an additional broadband Doppler-insensitive waveform and are typically plagued by clutter generated false alarms. Broadband Doppler-sensitive waveforms may have the ability to meet the DCL needs for both high- and low-Doppler targets while reducing the overall energy transmitted by the active sonar source. If successful, this approach will allow increased persistence of energy-constrained sonar systems and reduce the risk to marine mammals arising from anthropogenic sound in the marine environment. The problem to be solved in this effort is the development and evaluation of candidate broadband Doppler-sensitive waveforms meeting the DCL needs of both high- and low-Doppler targets as well as the receiver signal processing and advanced information processing required to exploit these waveforms. Waveform and receiver design must account for realistic Doppler-spreading induced by the environment (e.g., surface or scatterer motion) and the sonar system (random source and receiver motion). Evaluation of the waveforms and algorithms must occur at least at the localization (tracker output) level and should be compared with a reasonable baseline waveform of equal transmit energy. Waveforms with bandwidth-to-center-frequency ratios that may be efficiently generated by existing source technology should be considered. Note that "low-Doppler" includes targets with zero radial velocity. PHASE I: Development and simulation analysis of proposed broadband Doppler-sensitive waveforms and relevant signal and information processing. Waveforms, detection and normalization algorithms should be developed and evaluated accounting for an appropriate amount of environment- and system-induced Doppler spreading. It is emphasized that innovative solutions not only to the waveform design, but also the detection and normalization algorithms in the receiver processing are required. Initial research and development on tracking algorithms appropriate for the proposed broadband Doppler-sensitive waveform should result in an analysis plan for Phase II evaluation and implementation. PHASE II: Extend and refine the signal and information processing algorithms to include tracking of both low- and high-Doppler targets. Performance must be quantified at the track output level and include comparison with an equal-energy baseline waveform comprising continuous-wave and frequency-modulated pulses followed by a tracker exploiting detections from both waveforms. Data from a sea-trial of opportunity (e.g., via ONR's LWAD Program) is to be acquired and evaluated for both the proposed and baseline waveforms with a focus on tracking targets with low and high Doppler amid clutter. PHASE III: Extension of the tracking algorithm to multiple targets and multiple sensors, acquisition and analysis of a larger data set in a cluttered multi-target environment, and packaging of software for implementation in fleet systems. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Successful development of broadband Doppler-sensitive waveforms and their corresponding signal and information processing would be immediately applicable to homeland security applications of diver detection and harbor defense. Other fields that might benefit include the aerospace industry for tracking airplanes or spacecraft and biomedical engineering for tracking tracer particles in turbulent fluid or for the Doppler imaging of blood flows. REFERENCES: KEYWORDS: Active sonar; multi-static ASW; signal processing; sonar tracking; broadband waveforms; Doppler-sensitive TPOC: John Tague
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