Enhanced Differential GPS Carrier-Smoothed Code Processing Using Dual-Frequency Measurements

ABSTRACT: This paper describes methods for using dual-frequency GPS data to improve the accuracy of carrier-smoothed code pseudorange measurements by eliminating the limitations imposed by ionospheric divergence. With these techniques, the steady-state time constant used in the smoothing filter can be vastly extended as long as continuous carrier tracking is maintained. When used for Differential GPS (DGPS), the smoothing requirements for the reference and remote receivers can be decoupled since there will be no need to contend with ionospheric divergence. A new DGPS architecture that exploits these dual-frequency smoothing techniques to improve the accuracy of code differential systems is presented. Applications of these techniques to stand-alone GPS navigation are also discussed.