Final Presentation of EL2-174 “A WR Based Implementation of Coherent Clock”

Last Updated: 04/05/2026 07:33     Created at: 04/05/2026 07:32

On April 29, 2026, Safran Electronics & Defense (Spain) presented the results of the NAVISP Element 2 project EL2‑174 “AWR‑Based Implementation of a Coherent Clock”.

The project aimed to demonstrate the feasibility of a distributed, coherent timing service capable of delivering sub‑nanosecond accuracy, robustness, and resilience for Global Critical Infrastructures (GCI), addressing emerging requirements from 5G / 5G‑Advanced telecom networks, national timing infrastructures, space ground segments, and defence applications.

The concept is based on a distributed clock ensemble, combining multiple heterogeneous clocks (Rubidium, Caesium, GNSS) coordinated via White Rabbit (WR‑PTP IEEE‑1588‑2019), without reliance on a single Grandmaster. The system continuously cross‑validates timing sources, mitigates anomalies, and maintains timing continuity during GNSS disruptions.

The solution was designed, implemented, and validated through comprehensive verification and validation campaigns, including:

• Definition of use cases, system requirements, and architectures for coherent timing services in critical infrastructures
• Implementation of agreement, timescale, and coordination algorithms within WR‑based nodes
• Development of a Distributed Clock Ensemble Server (DiCES) for data collection, ensemble computation, and clock steering
• Extensive laboratory verification using emulated Rubidium clocks and anomaly injection (phase jumps, frequency jumps, node failures)
• Validation campaigns at ESA ESTEC, integrating physical Caesium clocks and long‑duration operational tests
• Assessment of fault tolerance, recovery behaviour, scalability, and physical 10 MHz / 1PPS outputs

Key results include:

• Successful demonstration of a distributed coherent clock achieving sub‑nanosecond WR time distribution
• Proven robust behaviour under clock anomalies, including phase and frequency jumps, clock exclusions, and node failures
• Enhanced stability and robustness for Rubidium‑based ensembles, and improved robustness for Caesium‑based ensembles
• Continuous convergence between internal ensemble clocks and physical outputs
• Fully integrated software and hardware solution demonstrated in representative environments, reaching TRL 5
• Identification of required improvements for steering algorithms, GNSS integration, UTC alignment, and high‑performance variants

The project also defined a clear roadmap toward telecom and high‑performance timing markets, including compliance with ITU‑T cnPRTC requirements, multi‑site pilots, red/blue redundancy, integration of GNSS‑based clocks, and progression toward TRL 7 and product hardening. Extensions toward space ground and inter‑satellite timing ensembles were also outlined.

The project was co‑funded by NAVISP Element 2, which supports the competitiveness of European PNT and timing technologies through close collaboration with industry. The slides of the final presentation can be found here.