Over-the-Horizon Radar (OTHR) Waveform Design for Maneuvering Targets

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics 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 a methodology or algorithm for developing an ensemble of waveforms for OTHR applications against fast and maneuvering targets in endo environments that provide thumbtack range/Doppler resolution, resilient range/Doppler sidelobe suppression, and enable spectrum tailoring. OTHRs provide detection and tracking capabilities against potential threats within the atmosphere (aircraft, cruise missiles, hypersonic missiles, etc.) by refracting radio frequency (RF) energy within the ionosphere to extend radar coverage beyond line-of-sight. Waveforms must be resilient to ionospheric propagation effects including natural and human-made electromagnetic interference. Secondary objective is to understand the inherent electronic protection features of these waveforms. DESCRIPTION: New types of waveforms are needed to support the high frequency (HF) continuous wave (CW) transmitter that the government is developing for the OTHR Testbed, which will support US Air Force acquisition of a national OTHR system. The testbed would demonstrate and mature key technologies for NORTHCOM and INDOPACOM OTHR acquisitions in defense of against hypersonic threats. PHASE I: Develop a methodology or algorithm for defining multiple coded HF CW transmitter waveforms that produce thumbtack-type matched-filter response no range or Doppler ambiguities Matched-filter range/Doppler sidelobe peaks should be at least 1/TBP below the peak response where TBP is the time-bandwidth product of a single dwell Matched filtering must accommodate high-speed targets such that target Doppler offset is significantly greater than Waveform Repetition Rate Waveform-generation algorithm should include provision for tailoring transmitted spectrum of waveform such as enforcing suppression of out-of-band emissions Report potential electronic protection features of proposed waveforms PHASE II: Demonstrate resilience of Range/Doppler sidelobe suppression to ionospheric propagation effects including natural and human-made electromagnetic interference Model target returns and provide interface to Government furnished signal processing and tracking algorithm simulation. Compare relative performance between nominal linear frequency modulated (LFM) waveforms and representative substantiations of the thumbtack response waveform Delineate implementation requirements for real-time operation including throughput and buffering PHASE III DUAL USE APPLICATIONS: Integrated waveforms in OTHR transmitter testbed REFERENCES: Y. Abramovich, D. Dickey and V. Abramovich, "Spectrum-Controlled Waveforms Design with the Thumb-Tack Ambiguity Function for HF OTH Radars," 2023 IEEE Radar Conference (RadarConf23), San Antonio, TX, USA, 2023, pp. 1-6, doi: 10.1109/RadarConf2351548.2023.10149799 Y. Abramovich, D. Dickey and V. Abramovich, Spectrally Limited Periodic Waveforms for HF OTHR Applications, https://www.researchgate.net/publication/365189135_Spectrally_Limited_Periodic_Waveforms_for_HF_OTHR_Applications, November 2022 Radar Spectrum Engineering and Management, NATO Science and Technology Organization TR-SET-182, April 2017, https://apps.dtic.mil/sti/pdfs/AD1039816.pdf Approved for Public Release 24-MDA-11708 (5 Mar 24) KEYWORDS: over the horizon radar; OTHR; waveform; maneuvering; hypsersonic; cruise missile; high frequency; HF; transmitter