Coverage and Performance Predictions for the North-West European Loran-C System

Abstract

In 1991 six European nations, Denmark, France, Germany, Ireland, The Netherlands and Norway, agreed to co-operate in deploying a Loran-C system to cover North-West Europe and the North Atlantic Ocean. The system will comprise 9 stations arranged in 4 chains. In estimating the coverage which will be provided, the effects of signal attenuation, atmospheric noise, carrier- wave interference, skywave propagation, the change of envelope-to-cycle difference with range and transmitter timing uncertainty ,have all been taken into account. Contours of repeatable accuracy have been predicted for both conventional hyperbolic receivers, which employ the signals of a master and two secondary stations of a single Loran-C chain, and receivers which work in the semi-circular, cross-chain and master-independent modes. A standard receiver with specified bandpass, notch filter and tracking loop characteristics has been adopted as the basis for coverage and performance assessment. Further, in a rigorous search was carried out forgroup repetition interval (GRI) values which minimised the numbers of synchronous and near-synchronous interferers in the area covered by each chain. The very substantial variations of coverage with choice of GRI were explored and optimal GRI values selected.