OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Integrated Sensing and Cyber;Trusted AI and Autonomy 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: Exploit the radar backscattering return from the wake produced by a submarine mast to enhance detection and discrimination beyond what is possible when relying solely on the return from the mast. DESCRIPTION: The U.S. Navy requires an operational capability to detect submarine mast wakes from high altitudes using coherent radar waveforms that also reliably reject sea clutter detections. Submarine mast detection has always been one of the most challenging radar problems. Submarines deploy a variety of sensor masts including optical and electro-optical periscopes, electronic support, radio frequency direction finding, and radar. Maritime wide area surface search radars traditionally operate at low altitudes with non-coherent waveforms. At high and grazing angles coherent processing can add Doppler spectrum as a radar observable. If the Doppler spectrum of a mast's return can be adequately separated from that of the sea, then improved detection performance is possible. However, the radar cross section of the mast itself may be very small. Therefore, if the wake generated by the mast can also be exploited, additional performance is possible. Measurements of backscatter from real submarine masts is generally classified, although some measurements of masts have been published in the open literature [Refs 1 and 2]. Those measurements show that the backscatter is composed of the return from the mast, the wake generated by the mast moving through the water, and the clutter return from the surrounding ocean surface within the radar's antenna beam. Analysis of those measurements show the return from the mast, in this case with a Doppler shift placing outside the clutter spectrum, and a significant return from a wake. The sea clutter spectrum is also visible. It appears that the Doppler spectrum for the wake extends over about 3 m/s to 3 m/s, equivalent to a Doppler spread of about 400 Hz in X-band. The clutter extends over about 0.5 m/s to 1.5 m/s, or about 125 Hz in X-band. The target has a narrow spectrum, mainly confined to a single Doppler bin having a resolution of about 0.1 m/s. The total power in the wake appears to be comparable to the power from the mast alone. These results are a function of the test conditions and in some other cases the mast may have the same Doppler shift as the sea clutter returns and a clear separation in Doppler space cannot always be relied upon. In this SBIR topic, the Navy seeks to better understand the wake signature from the moving mast. More complex detection schemes might be considered; for example, those involving micro-Doppler signatures from the wake. An understanding of the wake magnitude and Doppler spread over the range of mast configurations, sea states, submarine speed, direction of movement relative to the prevailing seas and radar viewing geometry is needed to gain a comprehensive understanding of the feasibility of such schemes. 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. 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 in order 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. PHASE I: Complete comprehensive analytical and numerical assessments of how the wake generated by a moving submarine mast will supplement the hard body return for detection and discrimination performance improvements. Assume the grazing angle ranges from 5 to 20 degrees over a representative range of conditions. Consider probability of detection and false alarm rate as compared to those for the mast alone. Develop the basis for the discrimination approach which complements the hard body technique. Prepare an overall system architecture concept. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Work with the Navy to test and refine the approach developed in Phase I using experimental data provided by the Navy. Tune the approach to the data's specific conditions. The supplemental detection and discrimination approach should be sufficiently mature at the conclusion of Phase II that it could be integrated into a radar's submarine mast detection and discrimination system. Work in Phase II may become classified. Please see note in the Description section. PHASE III DUAL USE APPLICATIONS: Complete the automated processing capability for enhanced submarine mast detection and discrimination and integrate with a Navy maritime surveillance radar system. The techniques could be applied to a variety of small target detection capabilities in a maritime environment such as those needed by the Coast Guard. REFERENCES: 1. Anderson, F.; Naicker, K. and Mocke, J. C. Insights into factors contributing to the observability of a submarine at periscope depth by modern radar. Part 1-High resolution measurements. 2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC), September 2012, pp. 985-988. https://ieeexplore.ieee.org/abstract/document/6324976 2. Smit, J. C. and Cilliers, J. E. Insights into factors contributing to the observability of a submarine at periscope depth by modern radar: Part 2-EM simulation of mast RCS in a realistic sea surface environment. 2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC), September 2012, pp. 989-992. https://ieeexplore.ieee.org/abstract/document/6324977 3. National Industrial Security Program Executive Agent and Operating Manual (NISP), 32 U.S.C. 2004.20 et seq. (1993). https://www.ecfr.gov/current/title-32/subtitle-B/chapter-XX/part-2004 KEYWORDS: Submarine Masts and Periscopes; Wake Characterization; Electromagnetic Scattering; Doppler Processing; Radar; Maritime Surveillance
