Frosty

Questions & Answers / Clarifications

This document provides responses to technical questions regarding Government Furnished Information (GFI) and Data for the DARPA-PS-26-03 "Frosty" program.

• Array Geometry and Experiment Design: Performer input on experiment design, including array layout and signal processing algorithms, is needed as it's mutually dependent. Proposers are encouraged to provide preliminary experiment design inputs.
• Waveforms and Transmitters: The High-frequency Active Auroral Research Program (HAARP) transmitter is coordinated for use, operating from 2.7 to 10MHz with conventional linear frequency modulated waveforms. Bandwidths are typically limited to tens of kHz but can be higher. Collaboration with other transmitter operators is encouraged. All man-made illuminators in Phase 1 will be cooperative.
• Data Format: Data will be captured as in-phase/quadrature (I/Q) baseband data from each element, filtered to the transmission band of interest, with some wider bandwidth sets (e.g., 8 MHz). A read package for MATLAB will be provided.
• Beamforming: Element-level data will be provided, and performers will be responsible for any necessary beamforming. Array geometry and calibration coefficients will be provided, though coefficients may have insufficient accuracy for high-resolution techniques.
• Ionospheric Data: Oblique ionospheric sounding data is expected to be available, though not yet fully coordinated. Environmental/context data will also be provided.
• Phase 1 Focus: The program focuses on developing advanced processing techniques for noise-like waveforms that result from ionospheric propagation to detect and track targets. This involves controlled man-made sources, but also explores ambient endogenous illumination.
• Cost Proposals: Cost proposals are not required with the abstract submission, but a budgetary rough order of magnitude (ROM) is requested. A budget by WBS element is required with the oral presentation/proposal.

These clarifications provide essential details for proposers regarding data availability, experimental parameters, waveform capabilities, and submission requirements, directly impacting how proposals should be structured and what technical approaches are feasible.

Amendment / Modification

This amendment incorporates a revision on page 15, requiring offerors to include a rough order of magnitude (ROM) cost estimate for the proposed Phase 1 effort. This estimate should be presented as a concise statement on the title page. The title page itself does not count towards the five-page limit for the abstract.

• Page 15 (Abstract Content section regarding title page requirements).

• Offerors must now include a ROM cost estimate on the title page of their abstract submission. This does not affect the page limit for the abstract.

Amendment / Modification

This amendment incorporates the following revisions to the Program Solicitation (PS) DARPA-PS-26-03:

• A Table of Contents has been added on page 3.

• ATTACHMENT A: Proposers' Day Material has been included as an attachment on page 4.

• The table and figure numbering has been corrected on pages 7, 10, and 12.

• Page 3: Table of Contents added.

• Page 4: ATTACHMENT A: Proposers' Day Material added.

• Pages 7, 10, and 12: Table and figure numbering corrected.

No changes to proposal deadlines, requirements, or evaluation factors are indicated by this amendment. All revised text in the document is highlighted in yellow.

Solicitation / RFP / RFQ

This document outlines DARPA's solicitation for "Frosty," a program seeking innovative radar signal processing algorithms and analysis approaches to develop new sensing modes in the Arctic environment. Responses are expected to provide an end-to-end solution from raw data to target tracks.

• Development of new sensing modes for the Arctic environment.

• Provision of an end-to-end solution, from raw data to target tracks.

• Focus on leveraging noise-like illumination for arctic sensing.

• Addressing key risks including anisotropic radar illumination over unknown time-varying channels and hidden models with incomplete data.

• The government reserves the right to award an Other Transaction (OT) for Prototypes under 10 U.S.C. § 4022.

• This is not a Request for Proposal (RFP) or a Broad Agency Announcement (BAA).

• OT authority can be used under specific conditions, including participation by nontraditional defense contractors or small businesses.

• Abstracts and presentations will be evaluated per the program solicitation.

• Important Dates:

  • Posting Date: 18 December 2025
  • Questions Due: 7 January 2026, 5 PM Eastern Time
  • Abstracts Due: 30 January 2026, 4 PM Eastern Time
  • Oral Presentations Due: By Government request, estimated 4-5 weeks after Abstract submission.

• Offerors must have a Unique Entity ID (UEI) and be registered in the System for Award Management (SAM).

• Offerors must register in the Wide Area Work Flow (WAWF) system.

• Offerors must be determined responsible and not be suspended or debarred.

• DARPA-specific representations and certifications are required.

• Special consideration for nontraditional defense contractors and small businesses in OT awards.

• Testing will primarily occur in Central/Northern Alaska, including Point Barrow and Poker Flat Research Range.

• Phase 1 metrics include minimum detection range of 75 km, probability of detection >90%, and tracking required.

• Controlled Unclassified Information (CUI) handling and security protocols are detailed.

Solicitation / RFP / RFQ

This solicitation from DARPA's Strategic Technology Office (STO) seeks innovative approaches for radar algorithm development to achieve reliable long-range sensing in the Arctic radio frequency (RF) environment. The program, "Frosty," aims to develop technology for new sensing modes in the Arctic, enabling improved detection and tracking of low-flying air vehicles and slow-moving maritime vessels. This involves developing innovative radar signal processing algorithms and analysis approaches.

• Development of advanced processing techniques to utilize noise-like waveforms resulting from propagation through a turbulent ionosphere for target detection and tracking.

• Creation of a signal processing flow from baseband receiver samples to detect and track test targets.

• Development of a Frosty processing software suite.

• Conceptual design for a prototype and hardware processing capabilities.

• Multiple awards are anticipated.

• Type of instrument: Other Transaction Agreement (OTA) for Prototypes.

• Phase 1 period of performance: 18 months.

• Estimated funding level for Phase 1 awards: $1,000,000 to $3,000,000 per award.

• Total program duration: 33 months (Phase 1: 18 months, Phase 2: 15 months).

• Abstracts Due Date: January 30, 2026, by 4:00 PM (ET).

• Questions Due Date: January 7, 2026, by 5:00 PM (ET).

• Oral Presentations: By Government request, estimated 4-5 weeks after Abstract submission.

• Evaluation will be based on Technical Comprehension, Technical Ability, and Concept.

• Encourages submissions from all responsible sources, including large and small businesses, and nontraditional defense contractors.

• University Affiliated Research Centers (UARCs), Federally Funded Research and Development Centers (FFRDCs), and U.S. government entities are prohibited from proposing as performers.

• Attachments include references to relevant research papers.

• Phase 2 will be solicited separately.

Other / Unclassified

This document is a research paper introducing the Defense Advanced Research Projects Agency (DARPA) Defense Applications of Innovative Remote Sensing (DAIRS) program. The program explores technology to significantly improve over-the-horizon radar (OTHR) capabilities. Key areas of focus include:

• Mitigation of Doppler-spread, ionospherically-propagated clutter.
• Maritime vessel classification.
• Using ambient noise as an illuminator for passive high-frequency radar.

The paper details the physics behind ionospheric spread clutter and discusses mitigation approaches. It also explores the theoretical aspects and research challenges of passive ambient-noise radar, including its potential for object detection and localization. Finally, it touches upon maritime vessel classification using HF surface wave radar and outlines the program's development and test activities, including data collection efforts.

This document provides background and technical details on a DARPA program (DAIRS) related to advanced radar technology. While not a direct solicitation, it outlines research areas and technical challenges that could inform potential bidders about DARPA's interests in remote sensing, radar technology, clutter mitigation, and vessel classification. The program's approach to rapid contracting via a Disruption Opportunity (DO) is also mentioned, indicating a potential pathway for engagement.

Other / Unclassified

This document is a research paper titled "Passive Ambient Noise Radar via Cross-correlation." It explores the use of ambient radio frequency (RF) noise as an illumination source for radar applications, aiming to detect objects and understand the environment without active high-power transmissions. The paper details a theoretical model and analysis for passive noise radar, focusing on cross-correlation techniques using two receiving apertures. It investigates scenarios with isotropic noise fields and develops mathematical models for signal processing. The research is part of the DARPA Defense Applications of Innovative Remote Sensing (DAIRS) program.

This document is relevant to bidders interested in advanced radar technologies, particularly those exploring passive sensing methods. It outlines a novel approach to radar that leverages existing ambient RF noise, potentially enabling applications in austere environments where active transmission is not feasible. The paper provides a theoretical foundation and mathematical framework for understanding and developing such systems, which could inform proposals related to innovative sensing and radar technologies.