Results in GPS system time restitution with Kalman filters

The paper describes the restitution of the GPS system time by using a Kalman filter which calculates the GPS system time as well as the clock rate of the used local clock. For improving the quality of the filter results, the algorithm uses the data from all visible satellites, not just from a fixed lower limit of satellites (for example 4). For that the Kalman filter algorithm had to be modified in a manner to handle observation vectors of time variant order. The paper outlines the principle of operation of this Kalman filter and the system and observation model used. The capability of the filter will be shown by tests