Flight Evaluation of a Locata-augmented Multisensor Navigation System

Abstract

The Global Navigation Satellite System (GNSS) is a widely used technology for high accuracy positioning in support of many applications, including airborne mapping and sensor georeferencing. The integration of GNSS and an Inertial Navigation System (INS) is a critical navigation component in an airborne mapping system, because it can provide high update rate of solutions, platform attitude information and improved performance (e.g. accuracy, availability). However, GNSS signals can be easily blocked or interfered with, and sometimes the satellite geometry may not be good enough for high accuracy and high reliability applications. Therefore the development of alternative, non-GNSS-based navigation solutions has attracted increased interest in situations where GNSS system availability cannot be guaranteed. Locata is a groundbased navigation system which can transmit ranging signals at several frequencies in the 2.4 GHz Industrial, Scientific and Medical radio bands. Tracking of Locata signals allows additional range-like measurements to be made, which can be processed in a manner not unlike GNSS measurements. Hence the integration of GNSS, INS and Locata can address requirements for seamless precise positioning in many situations. This paper describes a flight test of a GPS+INS+Locata triple-integrated system. The test was conducted in October 2011, during a flight from Bankstown Airport, Sydney, to Cooma Snowy Mountains Airport. The Locata pseudorange measurements were collected and postprocessed to evaluate overall navigation performance and to investigate the limitations of such an integrated system.