Optimal Positioning of Pseudolites Augmented With GPS

摘要

Over the last decade or so,global positioning system (GPS) positioning has played an escalating role in navigation,and it has become a primary tool for precise positioning.However,in some applications (e.g.,urban canyons,valleys,deep open-cut mines and near-shore applications) the number of visible satellites may not be sufficient to reliably determine the user's position.In addition,GPS satellite availability tends to be a function of the observer latitudes,and some techniques (e.g.,phase smoothing) are sensitive to cycle slips,hence they require continuous data acquisition.Pseudo satellites,known as pseudolites (PLs),provide extra and continuous signals to GPS users so that they can significantly improve the satellite geometry and positional accuracy.PLs typically transmit pseudorange and carrier phase signals from the ground at L1 and L2 GPS frequency bands.Normally,standard GPS receivers with minor firmware modifications can track PL signals.