This paper investigates the use of ambient noise for passive radar illumination, a concept being explored under DARPA's Defense Applications of Innovative Remote Sensing (DAIRS) program. The research focuses on whether natural and man-made radio frequency (RF) sources can be utilized for radar without isolating individual emitters. It describes theoretical models for observations, including scenarios with independent noise sources distributed spherically, hemispherically, or in a plane. The paper develops a model for passive remote sensing through the cross-correlation of noise data received at two apertures, presenting both theoretical derivations and simulation results. This approach aims to provide an alternative to traditional high-power transmission radar, enabling applications in more austere environments. The DAIRS program, a rapid contracting initiative, is funding this innovative exploration of passive noise radar.

The DARPA Defense Applications of Innovative Remote Sensing (DAIRS) program, initiated in 2024, addresses challenges in over-the-horizon radar (OTHR) operating in the high-frequency band. The program focuses on three key areas: mitigating Doppler-spread, ionospherically-propagated clutter, classifying maritime vessels, and using ambient noise for passive high-frequency radar. DAIRS aims to improve surface wave radar capabilities to reliably monitor the Exclusive Economic Zone. It explores advanced techniques like polarization nulling and MIMO operation for clutter mitigation and investigates longer observation periods and multi-frequency/multi-angle processing for maritime vessel classification. The program also researches the application of passive remote sensing, similar to methods used in geophysics and oceanography, to radar, seeking to overcome challenges in illumination coherence, radar range equations, and environmental dispersion. The program utilizes a rapid contracting approach and involves extensive data collection and testing campaigns in both mid-latitude and low-latitude regions to develop and validate new technologies.

DARPA's Frosty program seeks proposals for innovative radar signal processing algorithms and analysis for Arctic sensing, specifically targeting challenging environments with noise-like illumination. The program, building on past initiatives, aims to overcome issues like anisotropic noise and auroral scintillation to improve target detection and tracking. Phase 1 focuses on achieving a minimum detection range of 75 km with over 90% probability of detection and accurate tracking. Testing will occur in Central/Northern Alaska, utilizing various targets and truth data. The solicitation, DARPA-PS-26-03, outlines key dates for abstracts and presentations, emphasizing Other Transaction (OT) authority for prototypes. Proposals must detail end-to-end solutions from raw data to target tracks, adhering to strict security and CUI guidelines, and considering non-U.S. participation and export controls.

DARPA's Frosty program (DARPA-PS-26-03) seeks innovative radar algorithms for reliable long-range sensing in the Arctic to detect low-flying air vehicles and slow-moving maritime vessels. The program, spanning 33 months with an initial 18-month Phase 1, focuses on developing advanced signal processing to utilize noise-like waveforms in the turbulent Arctic ionosphere. Proposers must submit a 5-page abstract for evaluation, and selected offerors will be invited for an oral presentation, potentially leading to a Phase 1 Other Transaction Agreement (OTA) award ranging from $1,000,000 to $3,000,000. Key metrics include a minimum detection range of 75 km and over 90% probability of detection. The acquisition strategy aims to reduce administrative burden and foster competition, with Phase 2 to be solicited separately.

DARPA's Frosty program (DARPA-PS-26-03) solicits innovative proposals for radar algorithm development to enhance sensing capabilities in the Arctic environment. The program aims to create new sensing modes for detecting and tracking low-flying air vehicles and slow-moving maritime vessels by utilizing noise-like signals propagated through the turbulent Arctic ionosphere. Phase 1 focuses on algorithm and concept development, off-line implementation, and testing, with anticipated awards ranging from $1,000,000 to $3,000,000 per award. Proposals are accepted via a two-step process: initial Abstract submission, followed by an invitation for Oral Presentations for selected offerors. The program emphasizes advanced signal processing techniques, with specific metrics for detection range, probability of detection, track accuracy, and timeliness.

This document outlines an expenditure-based prototype agreement (HR0011-XX-9-XXXX) between DARPA and a Performer, focusing on research and development of a specific prototype. It details the agreement's scope, including background, definitions, and goals, emphasizing the program's vision and technological impact. Key articles cover the term, project management, administration, obligation and payment, disputes, intellectual property rights (patents and data), foreign access to technology, safeguarding defense information, and follow-on production. The agreement is structured with milestones and payments tied to deliverables, requiring strict reporting and adherence to federal regulations. Attachments include task descriptions, report requirements, and funding schedules, highlighting the government's continuous involvement and commitment to national security interests.

This document outlines a sample 'Other Transaction for Prototypes' agreement between a performer (company name) and the Defense Advanced Research Projects Agency (DARPA). The agreement, identified by number HR0011-XX-9-XXXX, is an expenditure-based approach with milestones for research and development, specifically for a prototype. Key aspects include the scope of the agreement, its term, project management, financial obligations and payment via the Wide Area Workflow (WAWF) system, dispute resolution procedures, and intellectual property rights concerning patents and data. It also details restrictions on foreign access to technology, safeguarding covered defense information, cyber incident reporting, and the possibility of follow-on production contracts. The document emphasizes compliance with various federal regulations and includes attachments for task descriptions, reporting requirements, and payment schedules.

This document is a sample "Other Transaction for Prototypes" agreement (HR0011-XX-9-XXXX) between a performer and DARPA, under 10 U.S.C. § 4022. It outlines the terms for a research and development program focused on a specific prototype, with a total agreement amount and obligated funds. Key articles cover the scope, term, project management, administration, obligation and payment (fixed payments for milestones via WAWF), dispute resolution, patent rights (performer retains title with government license), data rights (government receives specified rights), foreign access to technology, safeguarding covered defense information (NIST SP 800-171 compliance and cyber incident reporting), and potential follow-on production. It also addresses property disposition, civil rights, security, public release of information, and a prohibition on certain telecommunications equipment from covered foreign countries. Attachments include the Task Description Document, Report Requirements, and Schedule of Milestones and Payments.

This document outlines an Other Transaction Agreement (OTA) for Prototypes between the Defense Advanced Research Projects Agency (DARPA) and a company for research and development. The agreement, identified by No. HR0011-XX-9-XXXX, focuses on developing a specific prototype, with a 1/3 cost share required from the performer. Key articles cover the scope, term, project management, administration, payment, intellectual property rights (patents and data), foreign access to technology, safeguarding defense information, follow-on production, property disposition, civil rights, security, and public release of information. The agreement emphasizes fixed payments tied to milestone completion, strict reporting requirements via the DARPA VAULT website, and adherence to various federal regulations, including those concerning telecommunications equipment and cyber incident reporting. It defines critical terms like "Government Purpose Rights" and "Unlimited Rights" for data, and details procedures for dispute resolution and the government's march-in rights for inventions and data.

The Defense Advanced Research Projects Agency (DARPA) has issued Agreement No. HR0011-XX-9-XXXX, an Other Transaction for Prototypes valued at $2M or under, utilizing a fixed approach with a Nontraditional Defense Contractor and no resource contribution. This agreement, authorized under 10 U.S.C. § 4022, outlines a research and development program for a specific prototype, with payments tied to milestone completion. Key provisions include detailed stipulations on patent and data rights, with the Performer generally retaining title to Subject Inventions while granting the Government a nonexclusive, paid-up license. The agreement also addresses foreign access to technology, property disposition, safeguarding covered defense information, cyber incident reporting, and prohibitions on certain telecommunications equipment. Reporting requirements are extensive, covering milestone, patent, and final reports, to be submitted via the DARPA VAULT website.