Abstract: A direct multilateration target tracking system is provided with the TOA time stamp as an input. A technique of tracking targets with varying receiver combinations is provided. Methods of correlating and combining Mode A, Mode C, and Mode S messages to enhance target tracking in a passive surveillance system are provided. A direct multilateration target tracking system is provided by TOA tracking and smoothing. A technique for selecting best receiver combination and/or solution of multilateration equations from a multitude of combinations and/or solutions is provided. A technique for correcting pseudorange values with atmospheric conditions is provided. A technique for improving height determination for regions of poor VDOP in a 3D multilateration system is provided.

Abstract: The surveillance system provides a means to augment Automatic Dependent Surveillance—Broadcast (ADS-B) with “look alike ADS-B” or “pseudo ADS-B” surveillance transmissions for aircraft which may not be ADS-B equipped. The system uses ground based surveillance to determine the position of aircraft not equipped with ADS-B, then broadcasts the identification/positional information over the ADS-B data link. ADS-B equipped aircraft broadcast their own position over the ADS-B data link. The system enables aircraft equipped with ADS-B and Cockpit Display of Traffic Information (CDTI) to obtain surveillance information on all aircraft whether or not the proximate aircraft are equipped with ADS-B.