Publications

Since 1990, the Airport Surveillance Radar-9 (ASR-9) has been commissioned and installed at more than 60 of the largest airports in the United States, and future installations are planned at more than 60 additional airports. After the first several systems were put into daily operation, air traffic controllers began to lodge complaints about the radar's performance. Problems included the detection of "phantom" aircraft caused by the reflection of beacon interrogation signals off buildings and other aircraft, the radar's losing track of targets during parallel approaches and departures, the inability to track highly maneuverable military aircraft through high-G turns, radar clutter caused by highways and weather, and system overloading as a result of signal returns from flocks of migrating birds. An initial investigation of the sources of these problems focused on the radar's post-processor. Nearly all of the problems could be addressed by additions to the post-processor software, but the post-processor was already running near capacity and there was no means for expansion. Thus, a new processor - the ASR-9 Processor Augmentation Card (9-PAC) - was designed to augment the existing system to allow for a significant increase in processing power. New algorithms were developed to run in 9-PAC to address the problems cited by the controllers.