ABSTRACT - The dynamic development of long-distance methods of time and frequency signal transmission over optical fibres is giving the opportunity to create optical networks with dedicated clock services. The CLONETS project, funded by the European Commission in the H2020 programme, is intended to accelerate the transfer of these technologies to industry and to strengthen the coordination between research infrastructures and research and education network providers, in order to prepare the creation of a sustainable, pan-European fibre network, providing high-performance clock services to European research infrastructures and supporting wider services to industry and society.
Long-distance methods of time and frequency transmission over optical networks have been developing rapidly in recent years. They have proven their excellent performance in long-distance transmission, both in laboratory tests and in real-field environments, on dedicated fibre or in parallel to data traffic on operational telecom networks. They are a promising alternative or complementary solution to other methods of time and frequency transfer due to their superior performance, which enables remote optical clock comparisons, and their enhanced reliability and resilience with respect to electromagnetic interference compared to satellite-based methods, which are used in many industrial and societal applications.