Next Generation Reference Clock Transfer System


Sebastjan Zorzut
I-tech, d.d., Slovenia


ABSTRACT - There are many geographically distributed systems in the world that need extreme time synchronization between all subsystems. The length of such systems is in the range of some hundred meters to some kilometers. Synchronization is done with long-term stable reference clock signal. Reference clock signal distribution can be done with so called radio over fibre technology where optical carrier is modulated with clock signal and transmitted to dislocated unit over optical fibre. Reference clock signal is reconstructed at that location. Long-term phase stability of such distributed clock signal is in the range of 0.01°, while added jitter remains in the range of some femto seconds. This article shows key development phases like prototyping, accurate performance measurements of basic blocks, integration of verified solutions in final product and final system testing. Development of reference clock distribution system is the result of collaboration of research, user and entrepreneurship sphere.

POVZETEK - V svetu se pojavlja vse več geografsko distribuiranih sistemov z ekstremnimi zahtevami po časovni sinhronizaciji osnovnih gradnikov. Takšni sistemi so velikostnega reda od nekaj 100 metrov do nekaj kilometrov. Sinhronizacija se izvaja z dolgotrajno fazno stabilnim referenčnim urinim signalom. Za distribucijo urinega signala se lahko uporablja tako imenovana ''radio over fiber'' tehnologija, kjer z referenčnim urinim signalom moduliramo optični nosilec, katerega prenesemo na dislocirano enoto preko optičnega vlakna, in ga tam rekonstruiramo. Dolgotrajna fazna stabilnost distribuiranega urinega signala dosega vrednosti 0.01°, dodani fazni šum pa ostaja na nivoju nekaj femto sekund. V prispevku so prikazane ključne faze razvoja takšnega sistema, kot so prototipiranje, natančne meritve posameznih podsklopov sistema,integracija preverjenih rešitev v celoto in končno tesitranje sistema. Razvoj sistema za prenos referenčnega urinega signala je plod sodelovanja raziskovalne, uporabniške in podjetniške sfere.