Patent ID: 8164514
Filing Date: 2012-04-24
Classification: G01S

Abstract:
1. In an area that is overlapped by signals from a plurality of unsynchronized signal transmitters that are positioned at locations in said area, a method of calculating a position, velocity, and attitude for a moving object within said area, comprising the steps of: providing at least one sensor within said moving object that produces linear displacement measurements and angular displacement measurements in response to motion; starting from an initial position at an initial time, calculating a dead-reckoning navigation solution for said moving object by integrating said displacement measurements generated in a time period since said initial time; providing at least one reference displacement receiver within said moving object that produces referenced displacement measurements from said signals of said unsynchronized signal transmitters, wherein said referenced displacement measurements include radial displacement measurements that are derived from parameters embodied by said signals, and wherein said parameters include carrier phase measurements; calculating a corrected dead-reckoning navigation solution utilizing said referenced displacement measurements and said dead-reckoning navigation solutions, wherein said corrected dead-reckoning navigation solution includes values for position, velocity, and attitude, and predictions of radial displacement, wherein said step of calculating a corrected dead-reckoning navigation solution includes the substeps of; generating errors between said carrier phase measurements and said radial displacement predictions; applying an estimator to produce signal corrections to said dead-reckoning navigation solution; obtaining temporal change of carrier phase measurements; comparing a difference between said temporal change of carrier phase and said radial displacement predictions to predefined thresholds; excluding said signal corrections from said estimator when said difference exceeds said predefined thresholds; and de-weighting said signal corrections when said difference stays within said predefined thresholds.