TECHNOLOGY AREAS: Air Platform, Ground/Sea Vehicles, Sensors, Electronics

ACQUISITION PROGRAM: PMA-264, Air ASW Systems; PMA-290, Maritime Surveillance Aircraft

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Develop a means to detect targets in the reverberation return as well as in forward scatter where the ensonification wave (source energy) overwhelms the resonification waveform.

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. Unfortunately, in littoral areas reverberation can obscure the return from a target as there is presently no means to discriminate between target return and bottom return. Even with the strength of forward scattered (FS) energy, there is no means presently for a receiver in the FS area to discriminate between the ensonification wave and the diffracted (resonification) wave. Recent improvements in the state-of-the-art include the use of an array of co-located pressure and pressure gradient (velocity) transducers and the use of DIFAR sensors.

A new approach is required that can realistically provide active sonar detection improvement. Improved signal to noise ratio for the active sonar case is also desirable. Potential risks such as phase noise or target-environment compromises should be addressed as well as the possibility of implementing the sonar detection improvement as an array of pressure and pressure gradient (velocity) transducers.

PHASE I: Develop innovative signal and information processing algorithms. Determine the risk factors of the proposed technology and quantify the effects of system and environmental noise as related to pressure sensors, pressure gradient sensors and correlated pressure and pressure gradient sensors. Prepare a plan for demonstrating the resulting innovative technology.

PHASE II: Extend and refine the signal and information processing algorithms. Fabricate a floating breadboard prototype system to demonstrate the innovation. Performance must be quantified at the system output level (operator display) and include comparison with established active coherent continuous wave (CW) systems. In this phase the �operator display� may be either an actual aircraft system or it may be a representative system of the vendor�s choosing. Investigate the possibility of extending the technique for use in target classification.

PHASE III: Coordinate implementation of the innovation into a new sonobuoy as well as into an existing aircraft antisubmarine (ASW) system. Convert the algorithms innovated in Phases I and II for supporting the technology into source code for an aircraft sonar acoustic system. Coordinate field tests to gather and analyze data to improve and verify signal processing.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Successful development of active coherent pressure and pressure gradient waveforms and their corresponding signal and information processing would be immediately applicable to homeland security applications of diver detection and harbor defense.

REFERENCES:
1. Urick, Robert J. "Principals of Underwater Sound,", 3rd Edition, McGraw-Hill, Inc., 1983.

2. Kinsler, L.E. and Frey, A.R., "Fundamentals of Acoustics", John Wiley & Sons, 1982.

3. Burdic, William S. "Underwater Acoustic Systems Analysis" Prentice-Hall, Englewood Cliffs, NJ, 1984.

4. B.R. Rapids, G.C.Lauchle, "Processing of Forward Scattered Acoustic Fields with Intensity Sensors", Proc. Oceans 2002, 1911-1914.

5. B.R. Rapids, G.C. Lauchle, "Vector Intensity Field Scattered by a Rigid Prolate Sphereiod", J. Acoustic Soc. Am. 120 (1): 38-48 (2006).

6. N.K. Naluai, G.C.Lauchle, "Intensity Processing of Vector Sensors in the Bi-Static Regime", J. Acoustic Soc. Am. 119 (1): 3446 (2006).

7. N.K. Naluai, G.C.Lauchle, "Acoustic Intensity Methods and Their Application to Vector Sensor Use and Design, The Pennsylvania State University, Graduate Program in Acoustics, Report No 2006-01, November 2006., J. Acoustic Soc. Am. 119 (1): 3446 (2006) (2006).

KEYWORDS: Active Sonar; Signal Processing; Sonar Tracking; Coherent Waveforms; Pressure Gradient; Target Detection/Target Classification

** TOPIC AUTHOR (TPOC) **

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