Quantum-secured time transfer between precise timing facilities: a field trial with simulated satellite links

Global Navigation Satellite Systems (GNSSs), such as GPS and Galileo, provide precise time and space coordinates globally and constitute part of the critical infrastructure of modern society. To reliably operate GNSS, a highly accurate and stable system time is required, such as the one provided by several independent clocks hosted in Precise Timing Facilities (PTFs) around the world. The relative clock offset between PTFs is periodically measured to have a fallback system to synchronize the GNSS satellite clocks. The security and integrity of the communication between PTFs is of paramount importance: if compromised, it could lead to disruptions to the GNSS service. Therefore, securing the communication between PTFs is a compelling use-case for protection via Quantum Key Distribution (QKD), since this technology provides information-theoretic security. We have performed a field trial demonstration of such a use-case by sharing encrypted time synchronization information between two PTFs, one located in Oberpfaffenhofen (Germany) and one in Matera (Italy)—more than 900 km apart. To bridge this large distance, a satellite-QKD system is required, plus a “last-mile” terrestrial link to connect the optical ground station (OGS) to the actual location of the PTF. In our demonstration, we have deployed two full QKD systems to protect the last-mile connection at both locations and have shown via simulation that upcoming QKD satellites will be able to distribute keys between Oberpfaffenhofen and Matera, exploiting already existing OGSs

NAVSIM A tool to assess the performance of the future Galileo system by simulation

The GNSS simulation tool NAVSIM and potential applications will be presented. It is an end-to-end simulator for satellite navigation systems to assess the performance of the navigation solution based on simulated signals in terms of accuracy. The tool is to be used for investigations of Galileo performances. In a similar way it will provide criteria for the architectural design of a ground-based testbed to provide Galileo signals and test different user applications. The tool recently has been modified to meet particular requirements when checking railroad applications

GALILEO - Only a Better GPS or More? Performance Analysis with the Tool NAV-SIM

Since the European Commission (EC) decided to built up an own civil global navigation satellite system called Galileo, many people are asking why the EC want to built up an additional system. They say that they can use without any costs the U.S. navigation system GPS and, therefore, there is no need for the European GALILEO for the applications. But this is not really true. For some special applications GPS is not utilisable because it is no guarantee for the availability of the system

System Design and Simulation for a Future European Navigation Satellite System

DLR developes in co-operation with DSS a system designfor an European contribution to the future Global Navigation Satellite System GNSS2. To reduze the risk some components of the new system should be simulated first. With the simulation it is possible to answer questions of technologies with relative low additional costs