Radio Navigation: Perspectives and Challenges

摘要

Society, including many European governments, has a strong belief in the reliability of today's primary radio navigation system, GPS. Unfortunately, space-based as well as terrestrial-based systems have some serious limitations that cannot be ignored if continuity of service plays a key-role in the process in which these systems are used. The paper indicates some weaknesses of radio navigation systems seen from the provider side as well as from the user side. Attention is paid to the problem that GPS outputs 3D positions in e.g. WGS84 while map data could be given in another geodetic system. So, ship or aircraft positions can only be related through a common grid definition. This differs from e.g. ILS that is 'attached' to the runway and VOR/DME/NDBs that are directly related to airways. Attention is given to the rather dissimilar behaviour of Loran-C, the only other wide-area radio navigation system being operational in the US, and large parts of Europe, Russia and Asia. It is discussed why the integration of GPS and Loran-C can offer some cost-effective benefits for use in city areas, in forests and in mountainous environments. Further, Loran-C and Eurofix can offer a cost-effective solution for SBAS -WAAS and EGNOS - backup in all areas where the geostationary SBAS satellites cannot be received. The backup needed for GPS for timing services to the telecommunication field can be solved by Loran-C and Eurofix as well.