The U.S. Navy is seeking an SBIR solution to develop a high-gain, low-frequency sonobuoy array for improved anti-submarine warfare detection and directional sensing. The effort calls for an A-size, deployable vertical line array of vector sensors with advanced signal processing, beamforming, and communications compatibility to support long-range passive detection. Key requirements include operation below 500 Hz, deep-water use to 1,000 feet, 8 hours of life, at least 17 dB array gain, 96 dB dynamic range, and compliance with STANAG 4718, with work in later phases potentially becoming classified and limited to U.S.-owned and operated firms able to hold secret clearances. The opportunity is open, with applications due June 3, 2026, and the solicitation identified as DON26BZ01-NV006 under solicitation number 26.BZ.

## Description

To enhance anti-submarine warfare (ASW) detection and directional sensitivity in deep waters, the U.S. Navy requires a high-gain directional, low-frequency (&lt; 500Hz) sonobuoy array, housed in an A-size form factor. It is expected that array gain will be achieved by using modelled and measured vertical noise profiles. The system must leverage novel sensor configurations and array geometries to maximize low-frequency Signal-to-Noise Ratio (SNR) while remaining compatible with existing sonobuoy communication and processing platforms. Advanced beamforming, signal processing, and robust hardware integration are crucial for extended detection ranges and minimized false alarms. Environmental factors like multipath interference, ambient noise, self-noise, and sensor stability must be addressed to ensure reliable performance in contested environments. This sonobuoy will bolster fleet ASW capabilities by delivering superior signal clarity, longer-range detection, and a decisive operational advantage through improved sensor capabilities and operational durations. The objective is to develop a high-gain, low-frequency vertical line array of vector sensors capable of long-range passive detection and enhanced signal processing, deployable in an A-size form factor. The system will be deployed from Navy Maritime Patrol and Reconnaissance Aircraft, have capability across multiple operational environments, and will utilize the necessarily varied hardware configurations, passive processing, and frequency characteristics to consistently achieve critical ASW metrics.The sonobuoy must support deep-water tactical operations. Deployment depths up to 1000&rsquo; and 8 hours of life is required. The array design will provide 17 dB of gain at the design frequency in a three-dimensional isotropic ambient noise field as a minimum. The maximum saturation level will be 128 dB/&micro;Pa at 100 Hz with a total dynamic range of 96 dB. The sensor solution must be low power and fit within an &quot;A&quot; size sonobuoy (4.875-inch diameter x 36-inch length, weight under 40 pounds). Acoustic data sent to the aircraft from each vector sensor shall consist of Omni, Sine, and Cosine data. The communications link must comply with NATO's STANAG 4718. Long term plans include using the array in a persistent sonobuoy.Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by 32 U.S.C. &sect; 2004.20 et seq., National Industrial Security Program Executive Agent and Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA) formerly Defense Security Service (DSS). The selected contractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances. This will allow contractor personnel to perform on advanced phases of this project as set forth by DCSA and NAVAIR to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material during the advanced phases of this contract IAW the National Industrial Security Program Operating Manual (NISPOM), which can be found at Title 32, Part 2004.20 of the Code of Federal Regulations.

## Objective

Develop a high-gain, low-frequency vertical line array of vector sensors capable of long-range passive detection and enhanced signal processing, deployable in an A-size form factor.

## Phase I

Establish the baseline sensor requirements working in conjunction with the Navy Technical Point of Contact (TPOC). Perform comprehensive analytical and numerical modeling to define the optimal design of the sensing element and array for achieving the necessary gain using low frequency vertical noise profiles. Concurrently, develop a preliminary system architecture that addresses array geometry, deployment mechanisms, and communication protocols. Conduct trade studies on various sensor technologies, including velocity sensors, to select the most effective array configuration. Environmental noise factors will also be evaluated to determine their impact on overall system performance. Conduct trade studies on passive processing enhancements and adaptive beamforming to maximize detection range at these low frequencies.&nbsp;A proof-of-concept simulation of the acoustal array will be developed to demonstrate the feasibility of the proposed approach, guiding both design decisions and risk mitigation. The Phase I effort will conclude with the generation of a high-level prototype design to be implemented during Phase II, ensuring a clear path from concept to operational capability.&nbsp;Demonstrate materials/software/hardware required for prototype development can be sourced, produced, or obtained within a reasonable timeframe to allow for prototype development without requiring design changes due to unavailability, backorders, or extended lead times.&nbsp;Demonstrate that preliminary testing/modelling has been performed on the materials/software/hardware showing that they possess the characteristics used for modeling or that at least the component has the characteristics and performance required for the system to achieve the objectives.&nbsp;Phase I Requirements:<ul><li>Test design concepts(s) that have been demonstrated and validated to meet the objectives and can be scaled down to fit within the A-size constraints.</li><li>Awardee must provide a full report outlining where their models have been performed with sufficient accuracy and depth to produce meaningful results to meet the objective.</li><li>Demonstrate that preliminary testing/modelling has been performed on the materials/software/hardware showing that they possess the characteristics used for modeling or that at least the component has the characteristics and performance required for the system to achieve the objective.</li><li>Awardee must also prove the models and results provided in the report originated from the SBIR effort and provide evidence that the raw materials/software/hardware required for prototype development can be sourced, produced, or obtained within a reasonable timeframe to allow for prototype development without requiring design changes due to unavailability, backorders, or extended lead times.</li></ul>&nbsp;The Phase I effort will include prototype plans to be developed under Phase II.

## Phase II

Develop and test prototype(s) of the low frequency sensing element and/or acoustical array to verify Phase I performance predictions. Conduct trade studies on passive processing enhancements and adaptive beamforming to maximize detection range at these low frequencies. Quantify key performance metrics through a combination of laboratory and open water testing.&nbsp; Extrapolate the expected performance for the intended mission(s).&nbsp;Work in Phase II may become classified. Please see note in Description section.&nbsp;PHASE II OPTION OR CATAPULT PHASE II: Identify and develop deployment mechanisms and communication protocols. Design and fabricate an over-the-side deployable sonobuoy prototype rooted in Phase II findings and conduct over-the-side testing in both controlled facilities and actual aquatic environments to validate performance.&nbsp;&nbsp;Integrate beamforming and signal processing algorithms optimized for the low-frequency range, ensuring robust detection and adaptation under varied ambient noise conditions.&nbsp;Provide a thorough evaluation of the system’s capabilities in deep-water scenarios, refining hardware and software elements in collaboration with domain experts.&nbsp;Finalize the design concept by detailing a comprehensive roadmap for Phase III transition, including manufacturability considerations and integration with existing ASW platforms to maximize system synergy.&nbsp;Conduct a study to determine the feasibility of extending the concept to a persistent capability with an operational life of 24 hours or greater.&nbsp;Work in Catapul Phase II may become classified. Please see note in Description section.

## Phase III: Dual Use Applications

Develop a production-ready design and specification for the Phase II solution and its accompanying algorithms, then proceed with integrated engineering and operational testing of the air-deployed system to verify full operational functionality in Navy-supported scenarios. Demonstrate the system&rsquo;s adaptability and resilience in diverse maritime environments, ensuring seamless integration with Navy airborne ASW platforms and laying the groundwork for operational deployment. Upon successful qualification, transition to the Fleet and refine operational parameters through at-sea trials, leveraging real-world performance data.Lastly, explore commercial applications, including marine mammal detection, underwater resource exploration, and environmental monitoring, to extend the solution&rsquo;s utility beyond Navy missions.Technology developed under this SBIR topic could be leveraged to achieve smaller and lighter systems capable of attaining key ASW measurements. This type of system capability may be of interest to the undersea mapping, exploration, seismology, and weather communities and used for monitoring marine mammals or icebergs. Government agencies such as the National Oceanographic and Atmospheric Administration (NOAA) and the Department of Commerce are continually trying to upgrade their measurement and data collection capability. These sensors could fulfill a need to provide in-situ measurements for low rfequency acoustics. By developing reliable, low-cost sensor components, more capability and performance can be achieved.

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The DON26BZ01-NV006 project seeks to develop a high-gain, low-frequency sonobuoy array for enhanced anti-submarine warfare (ASW) detection. This A-size deployable system will utilize vector sensors and advanced signal processing to achieve long-range passive detection of submarines at frequencies below 500Hz. Key requirements include a minimum 17 dB array gain, a 96 dB dynamic range, deep-water operation up to 1000 feet, and an 8-hour operational life. The technology is restricted under ITAR/EAR, requiring U.S. ownership for contractors and the ability to handle classified information. Phase I focuses on sensor and array design, modeling, and preliminary system architecture. Phase II involves prototype fabrication, testing in aquatic environments, and refining algorithms. Phase III aims for production-ready design, fleet integration, and explores dual-use applications such as marine mammal detection and oceanographic research.

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