Reflection elimination in secondary surveillance radar

Secondary Surveillance Radar in Air Traffic Control has evolved from a mere labelling device in support primary radar to a high integrity plotting system inits own right with primary radar relegated to the support role. This change in concept has placed increased demands on the system and there is a greater awareness of the shortcomings and idiosyncrasies which previously were unnoticed or accepted, among which is the problem of reflections causing false target reports. This paper outlines the nature of the difficulty and some of the principal methods for reducing it to an acceptable level.