||Kirtland Air Force Base, NM 871175776
|Khanh Dai Pham
The Air Force seeks solutions to enable broad adoption of emerging time-keeping technologies and network synchronization protocols for a multi-source PNT capability that is essential to regional and/ or local areas of interest composed of cooperative remote platforms with continuity of information synchronization and command and control for joint all-domain campaigns. An integrated multi-source PNT capability will be determined to be regionally and/or locally capable if it collectively maintains accurate PNT information over the limited time required by a specific mission and cooperatively provides remote platforms with the best possible realization of Universal Coordinated Time (UTC), in addition of other aids of local atomic clocks, GPS receivers, etc. required over the limited area when global PNT information may not be available.
Specifically, regional and/or local PNT sources are those which are available from remote attritable platforms over a limited geographical area or are available at mission-essential levels of precision for a limited time because of phase and frequency offsets, unknown phase jumps, short-term noises, etc. which in turn require recalibration. As potential complements to GPS as part of a resilient integrated PNT architecture, these cooperative remote platforms providing regional and/or local PNT service coverages are enabled by wireless communications and data networks. Very often, all the remote platforms need to have a common Universal Coordinated Time (UCT) reference. Consequently, innovative standards and protocols pertaining to networked time transfer and synchronization for regional and/or local sources of PNT information are necessary. Prospective solutions should consider: i) Complex ad-hoc networks, including tree-structure based, cluster-structure based, and fully distributed; ii) Network synchronization with asynchronous communications with reliability and bandwidth requirements; iii) Two-way time transfers against asymmetric propagation delays, Sagnac effects, and hardware operations; and iv) Convergence rates, robustness, stability, and scalability subject to network sizes and member source qualities. Furthermore, challenges and the need for further research and development – related to programmability may include but are not limited to: greater use of artificial intelligence and autonomous agents, human hierarchical guidance or in-the-loop decision, and translation of inevitable uncertainty and variability associated with individual PNT sources to achieve specific common network time synchronization accuracy and resilience metrics.
1. Department of Defense, “Goal 2: Enhance the Delivery, Diversity, and Resilience of Position, Navigation, and Timing (PNT) Information”, DoD C3 Modernization Strategy, Sept 2020. https://dodcio.defense.gov/Portals/0/Documents/DoD-C3-Strategy.pdf.
2. Breakiron, Lee A., et al. "The accuracy of two-way satellite time transfer calibrations." Proceedings of the 36th Annual Precise Time and Time Interval Systems and Applications Meeting. 2004.
3. K. D. Pham, “Systems and Methods of Resilient Clock Synchronization in Presence of Faults,” US Patent #11,509,451, November 03, 2022
Remote Platforms; Regional and/or Local Multi-Source PNT; Universal Coordinated Time; Networked Time Transfer and Synchronization; Resilience Metrics; Programmability