Integer phase clock method with single-satellite ambiguity fixing and its application in LEO satellite orbit determination

Fixing single-satellite GPS carrier phase ambiguity could significantly improve the orbit accuracy of low earth orbit (LEO) satellite. Currently, the CNES/CLS,Wuhan University and CODE have published GPS integer phase clock products applied to single-satellite ambiguity fixing. In this paper,the integer phase clock method is used for single-satellite ambiguity fixing, and it is applied to the precise orbit determination of LEO satellite. Then, the application performances of integer phase clock products provided by different agencies in single-satellite ambiguity fixing and LEO satellite orbit determination are compared and analyzed. For GRACE-FO formation satellites, about 94% ambiguities could be fixed based on different products provided by the three agencies.Orbit solutions generated using the products from the three agencies can achieve an RMS of around 0.9 cm checked by satellite laser ranging data.Compared with ambiguity-float orbit solutions, the accuracy of absolute orbit determination with single-satellite ambiguity fixing is improved by about 30%.After fixing single-satellite ambiguities using the different products provided by CNES/CLS, WHU and CODE, respectively, the RMS of K-band ranging validation residuals for relative orbit solutions are reduced from 5.7、 5.4 and 5.3 mm to 2.1、 2.0 and 1.5 mm, respectively. The results show that the integer phase clock products provided by different agencies have similar performances in the single-satellite ambiguity fixing and orbit determination of GRACE-FO satellite