Digital Direction Finding (DF) System for the Next Generation Submarine Electronic Warfare (EW)
Navy SBIR 2015.1 - Topic N151-059
NAVSEA - Mr. Dean Putnam -
Opens: January 15, 2015 - Closes: February 25, 2015 6:00am ET

N151-059 TITLE: Digital Direction Finding (DF) System for the Next Generation Submarine Electronic Warfare (EW)

TECHNOLOGY AREAS: Sensors, Electronics, Battlespace

ACQUISITION PROGRAM: PMS-435, Submarine Imaging and EW Systems

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 section 5.4.c.(8) of the solicitation. 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 a new Submarine Imaging Mast Direction Finding (DF) capability for the Next Generation Submarine Electronic Warfare (EW) System.

DESCRIPTION: All Combatant Commands (COCOMs) have identified EW and Intelligence, Surveillance, and Reconnaissance (ISR) improvements, to support Force Application and Battlespace Awareness, as one of their highest priorities (ref 4,5). For submarines to meet the future COCOM ISR requirements they will need to improve the Direction Finding (DF) capability in the imaging mast. The proposed solutions to improve submarine DF must conform to open standards and approaches in the hardware and software design that shall readily support technological and functional advancement of the systems capabilities. DF is critical to improved situational awareness, ISR mission effectiveness, and overall ship safe operations particularly in the littoral operating regions.

The Next Generation Submarine EW system requires a DF capability that will be included in all future systems. This DF system will need to use common RF components, data pathways, and common processing capabilities to be included in the next generation architecture. It will need to be modular, scalable and fit into the digital framework, and current and future submarine mast configurations. The current DF system for Virginia Class submarines has six spiral DF horns that feed into a task tuned filtered bank (500 MHz instantaneous bandwidth) that provides an Intermediate Frequency that is converted to video via a set of SDLVA’s. Each of these six video lines are available inboard for DF processing. Unfortunately, this current design severely limits the DF capability across the broad spectrum of radar emission operating today.

Current Submarine DF capabilities are closely coupled with the radar wideband components in a stove-piped architecture. The current architecture does not allow for cost effective improvements in system performance and the introduction of new capabilities without significant impact to the existing system. Another limitation of the current configuration is that RF information (for the DF antennas) is turned to video in the mast and therefore only video (amplitude) processing can be performed with the below decks equipment (ref 1).

The Next Generation Submarine EW system will need to provide Direction Finding applications and solutions using available data from the existing DF arrays. This data will be defined through the interface layer of the new architecture, allowing algorithms in the processing layer to be developed for increased accuracy and capability.

The challenge is to improve direction finding in the constrained environment of submarine apertures and the RF environment. The use of digital data is preferred but the space constraint for turning the DF spiral RF into digital data is a confined space outboard of 3" x 3" x 10". It is preferred that DF improvements are predominately software based solutions but hardware and software solutions will be entertained. The small business will have to work closely with the government to ensure that the proposed solutions are feasible in the current (and future) submarine mast constraints (extremely small volumes and very thick radomes) (ref 2,3).

PHASE I: The company will define and develop concepts for a submarine imaging mast DF capability that meet the requirements as stated in the topic description. The company will demonstrate the feasibility of the concept in meeting Navy needs and will establish that the concept can be developed into a useful product for the Navy. Feasibility will be established by analytical modeling.

PHASE II: Based on the results of Phase I, the company will develop a DF prototype for evaluation. The prototype will be evaluated to determine its capability in meeting performance goals and Navy requirements for a Next Generation EW Digital DF for submarines. System performance will be demonstrated through prototype evaluation and modeling or analytical methods over the required range of parameters including numerous deployment cycles. Evaluation results will be used to refine the prototype into a design that will meet Navy requirements. The company will prepare a Phase III development plan that will provide requirements to transition the technology for Navy use.

PHASE III: If Phase II is successful, the company will support the Navy in transitioning the technology for Navy use. The company will develop a Next Generation EW Digital DF for submarines for evaluation to determine its effectiveness in an operationally relevant environment. The company will support the Navy for test and validation to certify and qualify the system for Navy use.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Government commercialization will be applicable across all submarine EW platforms. Modular DF techniques should be applicable to other Navy collection platforms (Triton, Firescout, EP-3, etc.).

Commercial applicability could be utilized in other agencies and potentially in the TELCOM industry for finding and localizing offending RF emissions.

1. Wiley, R. The Analysis of Radar Signals, 2nd ed. London, U.K.; Artech House Press, 1993.

2. Stephen V. Schell and William A. Gardner, "High Resolution Direction Finding," Handbook of Statistics, Vol. 10, copyright 1993 Elsevier Science Publishers B.V.

3. Joshua Radcliffe, Dr. Krishna Pasala, "Radar Direction-Finding Technique Using Spiral Antennas," AFRL-SN-WP-TP-2006-119. Retrieved from:

4. David L. Adamy, EW 102: A Second Course in Electronic Warfare; Artech House Press, 2004.

5. Dove, Rita. "Lady Freedom Among Us." The Electronic Text Center. Ed. David Seaman. 1998. Alderman Lib., U of Virginia. 19 June 1998.

KEYWORDS: Electronic support measures; Solid State Radars; direction finding algorithms; low peak power radars; Direction Finding Techniques; situational awareness

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