7774 20260108165331.0 10.1007/s00190-025-01991-1 DOI SCART-2026-0043 Guo, Jiang Multi-frequency PCO estimation for receiver antenna based on precise point positioning 2025 NO Geng, Jianghui Defraigne, Pascale Journal of Geodesy 99 2025 8 pascale.defraigne@ksb-orb.be published in REFERD