A Hybrid Timing System for Small Satellite Missions

Vednarayan S. Iyer, Emily J. Gokie and Thejesh N. Bandi

Peer Reviewed

Abstract:	Small-satellite missions in low-Earth, geostationary, and cislunar orbits increasingly demand low-SWaP (size, weight, and power) positioning, navigation, and timing (PNT) solutions that remain functional despite limited ground contact and intermittent GNSS coverage. Continuous two-way steering from Earth is often constrained by Deep Space Network scheduling, communication geometry, and limited access windows, motivating the development of autonomous onboard timing architectures. Chip-Scale Atomic Clocks (CSACs) offer milliwatt-level power consumption and compact volume, enabling spacecraft to maintain a local time-base, but their frequency drifts accumulate without external steering. To address this limitation, we propose a hybrid timing architecture that fuses a CSAC with a Pulsar Ensemble Timescale (PET) using a Vondrak– ´ Cepek filter (VCF) to optimally blend ? the short-term stability of the CSAC with the long-term stability of pulsars. We use the International Pulsar Timing Array second data release (IPTA DR2) to construct PET using a classical weighted average algorithm across three millisecond pulsars. The resulting hybrid timescale, CSAC-Pulsar Ensemble Timescale (CPET) exhibits the intended complementarity: the CSAC dominates at short averaging times, while pulsar disciplining improves stability at longer intervals. The ?z(? ) analysis shows a transition around a week, beyond which the hybrid provides an improvement approaching an order of magnitude at long-term.
Published in:	Proceedings of the 2026 International Technical Meeting of The Institute of Navigation January 26 - 29, 2026 Hyatt Regency Orange County Anaheim, California
Pages:	711 - 716
Cite this article:	Iyer, Vednarayan S., Gokie, Emily J., Bandi, Thejesh N., "A Hybrid Timing System for Small Satellite Missions," Proceedings of the 2026 International Technical Meeting of The Institute of Navigation, Anaheim, California, January 2026, pp. 711-716. https://doi.org/10.33012/2026.20511
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