Fibre-optic delivery of time and frequency to VLBI station

¹ AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków, Poland
e-mail: krehlik@agh.edu.pl
² Astrogeodynamic Observatory (AOS), Borowiec, Drapałka 4, 62-035 Borowiec, Poland
³ Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland
e-mail: amr@astro.uni.torun.pl
⁴ Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland
⁵ Joint Institute for VLBI ERIC, Postbus 2, 7990 AA Dwingeloo, The Netherlands
⁶ Orange Polska S.A., Obrzeżna 7, 02-691 Warsaw, Poland
⁷ Poznań Supercomputing and Networking Center, Jana Pawła II 10, 61-139 Poznań, Poland

Received: 14 February 2017
Accepted: 17 March 2017

Abstract

The quality of Very Long Baseline Interferometry (VLBI) radio observations predominantly relies on precise and ultra-stable time and frequency (T&F) standards, usually hydrogen masers (HM), maintained locally at each VLBI station. Here, we present an operational solution in which the VLBI observations are routinely carried out without use of a local HM, but using remote synchronization via a stabilized, long-distance fibre-optic link. The T&F reference signals, traceable to international atomic timescale (TAI), are delivered to the VLBI station from a dedicated timekeeping laboratory. Moreover, we describe a proof-of-concept experiment where the VLBI station is synchronized to a remote strontium optical lattice clock during the observation.