An Implementation of Zero Difference VRS Observation for Network-RTK

The principle of a VRS based network-RTK system is to use multiple reference stations to correct the error sources around the rover station,including tropospheric delays,ionospheric delays and also orbit errors.In this paper,we mainly discuss how to generate zero difference observations base on the double difference atmospheric delay.To ensure the quick ambiguity resolution on the rover station,the predict part of ultra-rapid IGS orbit is employed to correct the broadcast orbit,and also a sidereal day fitter is used to reduce the pseudorange multipath effect on the VRS station.In this paper,a 50 km baselines CORS triangle are used to test the algorithm,24 h results shows the single epoch ambiguity resolution success rate is 81.1% and the RTK algorithm get 97.6% fixed solution with the RMS of 1.1 cm in north,1.1 cm in east and 3.0 cm in up direction.