Estimating the Performance of IRGPS

Abstract

Indoor GPS behaves much like an automated theodolite system: each transmitter gives elevation and azimuth to every sensor, and two transmitters plus a scale bar fix a target in space. The catch is that measurement uncertainty depends strongly on where the transmitters and sensors sit relative to one another, and adding transmitters – which improves the result – makes the result harder to predict. Jim Cobb of Boeing's Materials & Process Technology organisation describes a way of estimating IRGPS performance for a planned setup, worked through a football-field example modelled in Spatial Analyzer.