Contents I. Introduction
The growing interest in PCL would be greatly enhanced if the detection performance of a complete PCL system could be modelled. Existing systems have been largely practical implementations in nature, consisting of a single receive site and using, potentially, numerous transmitters at different frequencies [1]–[3]. Carrying out flight trials to prove the performance of the systems is expensive, and due to the credibility gap associated with PCL, difficult to motivate. It will be some time before PCL systems are accepted into the mainstream of air traffic control sensors. The work [4], [5] at the University of Cape Town's Radar Remote Sensing Group (http://www.rrsg.uct.ac.za) is focussing on the implementation of a system that utilises multiple receivers spatially distributed, and a network of gap-filler broadcast transmitters at a number of frequencies. It became essential to be able to predict the performance of the system for potential receiver sites and different transmitter locations.
