Research project IM/RT/23/BOOSTED (Research action IM)
The most used technique for the accurate time and frequency (T&F) synchronization uses the metrological signals broadcasted by the global positioning constellations of satellites like GPS (US) or Galileo (Europe). It determines the frequency offset between remote clocks with an uncertainty of 10-16 in relative frequency with a one-day averaging. It is the most precise technique used so far at the Royal Observatory of Belgium (ROB) to disseminate UTC(ORB) on which is based the Belgian legal time. However, the T&F transfer using the GPS/Galileo signals is vulnerable to diverse interferences such as jamming and spoofing. It is thus inadequate for applications demanding higher precision and security.
The most promising alternative is the T&F transfer through optical fibers, making use of the existing networks dedicated to telecommunications. It overcomes the performances of the other techniques of T&F transfer by several orders of magnitude, thanks to the transmission medium, in which systematic effects altering the propagation delay are compensated. The purpose of this project is to deploy a new infrastructure of T&F transfer through the optical fibers in Belgium, called BOOSTED (Belgium Optical network for Optical frequency Standards and TimE Dissemination), see fig. 1, and to connect it to the European metrological network of optical fiber via the French REFIMEVE network.
A first aspect of the BOOSTED project is to disseminate UTC(ORB) with a precision of the order of the nanosecond, using the White Rabbit, an evolution of NTP/PTP. A link Gent < Brussels(ROB) > Leuven – Hasselt – Mol – Liège will be in operation by 2026.
In parallel, a second aspect of the BOOSTED project is to connect the ROB to the French network REFIMEVE in order to get access to an ultrastable frequency, of the order of 10-18 in relative frequency at one day. Hence, a second link Paris – Brussels(ROB) – Louvain-la-Neuve will carry this ultrastable signal by 2026. At long term, the REFIMEVE signal will be disseminated to any Belgian stakeholder thanks to the impulse of the BOOSTED project.
Relative frequency stability below 10-18 (@1 day) has applications in applied physics, for example in laser characterization, applied quantum mechanics, or clock manufacturing. The access to the ultra-stable signal will also enable to develop cutting edge research in diverse fields like e.g. nuclear waste process, photonics, quantum cryptography, frequency combs or high precision spectroscopy. An initial committee of future users has already been set up and put together research centers and stakeholders from KU Leuven, ROB, SCK-CEN, SMD, UGent, UCLouvain and ULB.
Finally, a European network of T&F transfer by optical fiber currently connects UK, France, Italy and Germany, while projects exist to link the operational local network in other EU countries, in a preparation phase for an integration into the European landscape of Research Infrastructures. This project will embed the nascent Belgium network to the EU infrastructure with a strategic and central play role.
