A Time Domain Atmospheric Noise Level Analysis

Lightning and other atmospheric noise interferes with Loran signal reception. This paper develops techniques to improve signal availability under these conditions. While the rootmean square (rms) electric field strengths may be quite large for a given lightning discharge, there is significant time between strikes where the background noise is only modest and signal reception is possible. By implementing a simple non-linear hole-punching algorithm, considerable performance gains may be realized over a linear receiver design. This study uses data from the CCIR to evaluate a hole-punching algorithm in the time domain. Analysis of the data provides justification for a 15dB reduction in the rms noise level when a hole-punch or other non-linear processing is used to mitigate atmospheric noise. With this reduction in noise level the availability and continuity of a Loran receiver will improve. This study constitutes part of the Loran Integrity Performance Panel’s on-going analysis of Loran receiver performance for RNP 0.3 approach.