DIRECT TO PHASE II - F7-Wideband Acoustic Receiver and Source (F7-WARS) Sonobuoy

Navy SBIR 24.2 - Topic N242-D05
NAVAIR - Naval Air Systems Command
Pre-release 4/17/24   Opened to accept proposals 5/15/24   Closes 6/12/24 12:00pm ET

N242-D05 TITLE: DIRECT TO PHASE II: F7-Wideband Acoustic Receiver and Source (F7-WARS) Sonobuoy

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Integrated Network Systems-of-Systems; Integrated Sensing and Cyber

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop and demonstrate an updated, evolved air-deployable receiver with a compatible source that can characterize the acoustic ocean environment in the F7 Low Frequency range and builds upon previous successful designs. The system will be deployed from Navy Maritime Patrol and Reconnaissance Aircraft, have capability across multiple operational environments, and utilize the necessarily varied hardware configurations, active and passive processing, and frequency characteristics to consistently attain key anti-submarine warfare (ASW) measurements.

DESCRIPTION: The capabilities of current Low Frequency F7 receiver/source sensors do not provide calibrated coherent receiver/source combination tailored for environmental characterization or advanced passive processing. Innovative sensor technologies are sought with enhanced electromechanical property ceramics that fill frequency, bandwidth, and responsiveness gaps for the transmitter and receiver elements that are capable of transmitting, collecting, and processing surveillance information. Enhanced signal processing techniques for both active and passive processing can enable improvements in capabilities within the entire Low Frequency acoustics band. There is a need within the Navy, and other DoD agencies, to characterize the ocean environment for pre-mission planning, environmental analysis, and marine mammal mitigation during training and operational trials, as well as achieve key ASW measurement capabilities at Low Frequency. Variations in acoustic frequencies necessitate changes in hardware configurations, acoustic propagation, and advanced signal processing capabilities. Advanced passive and active processing capabilities will need to be developed to achieve these measurements.

Tactical needs and munition transport capabilities make it difficult to meet all intelligence and mission planning requirements with existing hardware. Additionally, scenario characteristics such as transmission loss, bottom loss, reverberation, geo-acoustic characterization, obscuration, clutter, multipath, signal detection, and signal type vary with changes in acoustic frequency and may limit the performance of current intelligence gathering systems without the capability to gather and exfiltrate the information. System solutions should include both single unit concepts, paired source and receivers, as well as analysis into the feasibility of combined units and mission planning considerations.

The unit should be capable of both shallow and deep-water operations deploying the active and passive sensing elements through 500 ft (152.4 m) with both mission operating life and extended duration capability. Enhancements in passive processing should provide for significantly improved minimal detection levels. Coherent signals of interest are in the Low Frequency range, to include but not be limited to continuous waveforms (CW) and frequency modulation (FM) waveforms, with associated active processing improvements. The unit will also take advantage of the communication between the aircraft and sensor unit. This should be compliant with the NATO digital uplink format, STANAG 4718.

This expendable sensor solution should be low power and sized to fit within an A-size sonobuoy. A-size sonobuoy standards are as follows: dimensions of 4.875 in. (12.38 cm) diameter x 36 in. (91.44 cm) length and weight of 40 lb (18.14 kg) or less.

PHASE I: For a Direct to Phase II topic, the Government expects that the small business would have accomplished the following in a Phase I-type effort and developed a concept for a workable prototype or design to address, at a minimum, the basic requirements of the stated objective above. The below actions would be required to satisfy the requirements of Phase I:

1. Provide evidence of prior successful development, testing, or deployment in a relevant domain. The system should clearly demonstrate readiness for integration with Navy Maritime Patrol and Reconnaissance Aircraft. Furthermore, the proposal must emphasize the system's capability for uninterrupted operation across varied oceanic environments, underpinned by documented results or prototypes, which have effectively captured essential ASW measurements. Prior success in addressing similar challenges will be heavily weighted in evaluation.

2. Provide an intelligible forward plan that minimizes risk and redesign efforts by identifying and incorporating existing ASW technologies. While a combined source and receiver is ideal, solutions separating the source from the F7 receiver will be considered so long as the tradeoffs are clear.

3. Modeling and/or results of risk reduction experiments that validate the existing concept along with the expected application at a new frequency to be provided.

FEASIBILITY DOCUMENTATION: Offerors interested in participating in Direct to Phase II must include in their response to this topic Phase I feasibility documentation that substantiates the scientific and technical merit and Phase I feasibility described in Phase I above has been met (i.e., the small business must have performed Phase I-type research and development related to the topic NOT solely based on work performed under prior or ongoing federally funded SBIR/STTR work) and describe the potential commercialization applications. The documentation provided must validate that the proposer has completed development of technology as stated in the Phase I above.

PHASE II: Develop and fabricate an over-the-side prototype unit(s) operating in the F7 Low Frequency range and demonstrate in both acoustic facilities and the ocean environment. Prototype demonstrations will demonstrate successful completion of classified objectives (how the objectives are defined). Throughout this development phase, emphasize a comprehensive evaluation of the prototype’s performance under high-ambient and low-source level conditions, ensuring its adaptability and resilience in diverse acoustic settings. Collaborate with similarly focused domain experts and utilize feedback from preliminary tests to further refine and optimize the system at Low Frequency. Finalize the concept design and make recommendations for Phase III production-oriented designs, detailing potential challenges and solutions for scalable manufacturing. Explore integration pathways with existing Navy Maritime Patrol and Reconnaissance infrastructure to maximize system collaboration. Demonstrate the prototype’s ability to attain desirable ASW measurement capabilities at Low Frequency and provide a roadmap for iterative improvements and integration based on feedback.

PHASE III DUAL USE APPLICATIONS: Transition over-the-side prototype unit(s) into an air deployable sonobuoy system. Sensor must meet A-size packaging requirements specified in the PMA-264 Production Sonobuoy Specification. Testing will be required which verifies the sensor passes all required environmental, structural, and operational tests. These tests include but not limited to Environmental Exposure, Air Certification, Hazards of Electromagnetic Radiation to Ordnance (HERO), and Office of Naval Intelligence (ONI) certification.

Upon successful testing, Low Rate Initial Production (LRIP) will need to be successful for transition to the platform.

This technology/topic can benefit any entity that requires calibrated active target strength measurements within the underwater environment.


  1. Urick, R. J. "Principles of underwater sound for engineers (3rd ed.)." Peninsula Publishing, 1983.
  2. Holler, R. A.; Horbach, A. W. and McEachern, J. F. "The ears of air ASW: a history of US Navy sonobuoys." Navmar Applied Sciences Corporation, 2008.
  3. "Standardization agreement: STANAG 4718: Sonobuoy digital telemetry (Ed. 1)." North Atlantic Treaty Organization, The NATO Standardization Office (NSO), 4 November 2020.

KEYWORDS: Anti-Submarine Warfare; Sonobuoy; Low Frequency; Navy Underwater Active Multiple Ping; NUAMP; Acoustics; Intelligence


The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 24.2 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its Navy 24.2 SBIR Topics pre-release on April 17, 2024 which opens to receive proposals on May 15, 2024, and closes June 12, 2024 (12:00pm ET).

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