The Differential Vector Phase-Locked Loop for Global Navigation Satellite System Signal Tracking

A novel differential vector phase-locked loop (DVPLL) is derived that takes GNSS code-phase and carrier-phase measurements from a base station and uses them to maintain an integer ambiguity resolved quality solution directly in the vector tracking loop of a rover receiver. The only state variables estimated and used to create the replica code and carrier signals from the base station measurements are three position and two clock states for a static test. Closing the individual loops solely through the navigation filter makes this a pure vector method. For short baselines, where differential atmospheric errors are small, the DVPLL can be used on single-frequency data. An L1-only live-sky static test was performed using the method resulting in a 3D accuracy of 5.3 mm for an 18.5 m baseline. An acquisition algorithm is also developed to initialize the DVPLL. The algorithm performs a search in the space-time domain vice the measurement domain. An upper bound on the failure rate of the algorithm can be set by the user. The algorithm was tested on 24-h dual- and single-frequency CORS data sets with close to a 100% success rate and on a 15- min data set of single-frequency IF samples with a 100% success rate