Abstract :
The National Air Traffic Services (NATS) operates some 20 secondary surveillance radar (SSR) equipped stations throughout the United Kingdom. Radar data is plot extracted on site and fed to control centres in digital form and immediately displayed on radar screens. All data is recorded for any subsequent investigation that may be necessary. Plot position is presently registered to a precision of 1/16 nm in range and 0.0879 degrees in azimuth. Various inaccuracies such as multipath and reflections are associated with SSR. The article is concerned with the diffraction effect of obstructions on both monopulse and sliding window systems. It describes one technique which has proved useful in visualising the effect of nearby obstructions on the angular accuracy of the radar throughout 360 degrees and presents some of the results
