PICOSECONDS-LEVEL PRECISION INTER-SATELLITE TIME AND FREQUENCY TRANSFER FOR SYNTHETIC BEAMFORMING IN FREQUENCY RANGE 1 (FR 1) (ARTES 4.0 SPL 5G/6G 3F.061) - EXPRO+

Objective: The objective of the activity is to design and test inter-satellite time and frequency transfer techniques achieving picoseconds-level precision, enabling tight phasesynchronization between satellite nodes for FR1 band synthetic beamforming.TargetedImprovements: - Achieve phase synchronization precision of better than /16 at in FR 1. Enable scalable synthetic aperture and coherent signal combination between satellite nodes in LEOand MEO constellations.- Improve phase stability and coherence time by >1000 over current distributed clock synchronization.Description: Distributed satellite systems performing synthetic beamforming in the FR1 band require synchronization at picoseconds precision across all contributing satellite nodes in 2 upto 3 dimensions. This is essential to coherently align phases across satellites separated by hundreds of metres to kilometres and support applications such as high-gainaperture synthesis, enabling direct-to-device application as well as distributed sensing. This is required to complement position and navigation and timing techniques.This activity will design and prototype time / frequency transfer architectures that may rely on digital processing from user receive antenna, bidirectional links or broadcast,coupled with high-resolution phase tracking and active compensation of inter-satellite Doppler and propagation delay variations.The activity will- Identify representative use cases and architecture constraints for using 5G-NR distributed beamforming in the FR1 band, including co-existence with communication links.- Review available published techniques, papers and patents for PN as well as distributed time and frequency synchronization and trade off the ones applicable to this usecase- Design and evaluate several techniques for high-resolution time / frequency transfer using in-band inter-satellite links or dedicated links, using optical or RF.- Develop and implement a laboratory test bed simulating inter-satellite conditions (Doppler, delay, oscillator instability, orbital mechanics).- Test and evaluate synchronization performance using representative space-grade timing sources and communication links.