The surveillance system provides a means to augment Automatic Dependent SurveillanceBroadcast (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...http://www.google.co.uk/patents/US6806829?utm_source=gb-gplus-sharePatent US6806829 - Method and apparatus for improving the utility of a automatic dependent surveillance
