Hybrid Pulsar–Clock Ensemble Using Vondrak–Cepek Filtering for Spaceborne Timekeeping

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

Peer Reviewed

Abstract:	Small-satellite missions with limited ground contact and intermittent GNSS availability benefit from autonomous, low-SWaP timing solutions capable of maintaining long-term stability without continuous need for Earth-based steering. In this work, we present a hybrid timing architecture that combines a Miniature Atomic Clock (MAC) with a Pulsar Ensemble Timescale (PET) to exploit their complementary stability characteristics. The PET is constructed using four millisecond pulsar timing dataset from the International Pulsar Timing Array second data release (IPTA DR2). The two timing systems (MAC and Pulsars) are fused using a Vondrak– ´ Cepek filter, which optimally balances smoothness, fidelity to pulsar-derived time samples, and ? adherence to the MAC’s frequency information. The resulting hybrid timescale follows the standalone MAC at short averaging times and transitions to pulsar-dominated performance at longer times, yielding improved mid- to long-term stability. The transition occurs on timescales of few days, beyond which disciplining using pulsars provides a clear stability benefit.
Published in:	Proceedings of the ION 2026 Pacific PNT Meeting April 13 - 16, 2026 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	881 - 887
Cite this article:	Iyer, Vednarayan S., Gokie, Emily J., Bandi, Thejesh N., "Hybrid Pulsar–Clock Ensemble Using Vondrak–Cepek Filtering for Spaceborne Timekeeping," Proceedings of the ION 2026 Pacific PNT Meeting, Honolulu, Hawaii, April 2026, pp. 881-887. https://doi.org/10.33012/2026.20606
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