Further studies of ATCRBS based on ARTS-III derived data
December 13, 1974
Lincoln Laboratory has been examining digital data extracted from operational ARTS-III radar beacon processing systems for the past eighteen months, in an attempt to determine the capabilities of today's civil Air Traffic Control Radar Beacon System. Our original report on the subject, "Empirical Assessment of ATCRBS," (Ref. ), covered data gathered during the first six months of the study from the Andrews AFB (ADW), Boston (BOS), and Las Vegas (LAS) ARTS-III eqUipment. This report discusses analysis of data received since the completion of that initial report, which was gathered at the Ontario, California (ONT), Albuquerque (ABQ), Minneapolis St. Paul (MSP), Milwaukee (MKE), and Boston (BOS) ARTS-III sites, and also the Suitland, Md. en route radar site. The major topics considered here are false targets caused by multipath reflections, and asynchronous interference (fruit). Four different mechanisms resulting in false targets were observed in the data and are discussed in detail in the report. In addition, levels of asynchronous interference as measured and analyzed, and two procedures are discussed by which the characteristics of the interrogators responsible for the fruit (including location) can be determined. One of these is described in detail, and shown to yield results that agree closely with known parameters. Several other topics, including improper reply decoding, are also discussed.