Passive Sensing for Distributed Radars

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Trusted AI and Autonomy; Advanced Computing and Software; Integrated Sensing and Cyber;Integrated Network Systems-of-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 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 capabilities for passive sensing for distributed radars. Key technical objectives are: Passively collect radar reflections Measure the time difference of arrival (TDOA) of collected signals Determine the range of the object Calculate the location, heading, and speed of the object Develop techniques to provide accurate location, heading, and speed with degraded or no knowledge of the emitting source Provide information to determine how to size passive arrays for different mission areas DESCRIPTION: Typical sensors consist of a transmitter and a receiver (e.g. phased array radars). Passive sensors instead collect radar reflections using third-party transmitters in the environment (typically non-cooperative). Recent efforts have used this approach to perform passive sensing of objects. In order to further the technology being developed in this effort, this topic seeks the development of passive sensing of distributed radars to accomplish the Key Technical Objectives below. Potential solutions could take the form of either a new passive sensing approach, a new processing algorithm, or a combination of both. Passive sensors count on the existence of reference signals. These are signals typically from non-cooperative (unwitting) sources. With the reception of the reference signal, such passive systems can achieve successful results regarding target detection. Without reception of the transmitted signal or other prior information, it would be very challenging to perform target detection since both the transmitted signal and the channel response is completely unknown to radar receivers. When multiple incoming targets are considered, the scenario becomes even more complicated. The mixture of multiple target reflections is received at every receiver in the distributive radar system, and no extra information can be pre-obtained. PHASE I: Passively collect radar reflections and measure the time difference of arrival (TDOA) of collected signals. Potential solutions could take the form of either a new passive sensing approach, a new processing algorithm, or a combination of both. The overall system design at this point could be rough with many questions remaining to be answered, such as how the system would determine the range of the object or calculate the location, heading and speed of the object. PHASE II: System development would continue with the goals of both determining the bistatic range of the object and then calculating the location, heading, and speed of the object. Again, potential solutions could take the form of either a new passive sensing approach, a new processing algorithm, or a combination of both. PHASE III DUAL USE APPLICATIONS: The team should improve upon the technology and implement a full design. The improvements could be in the form of shrinking the size of the overall system, improving upon the hardware/software solution, and/or implementing lessons learned from Phase I and II. REFERENCES: Growth in Passive Radars for Air Defence and Maritime Suveillance: https://idstch.com/technology/electronics/passive-radar-systems-for-air-defence-and-maritime-surveillance Multi-target Detection by Distributed Passive Radar Systems without Reference Signals: https://ieeexplore.ieee.org/abstract/document/9417324 KEYWORDS: Passive, radars; distributed; sensing