Determination of real-time precise satellite clock offset based on multiple reference stations using regional CORS

In order to improve the accuracy and timeliness of real-time precise point positioning, by means of GPS (global positioning system) carrier phase observations collected in a regional CORS (continuous operational reference system) network and the IGU (international global navigation satellite system service ultrarapid) predicted ephemeris, the computation of real-time precise satellite clock offsets based on epoch-difference and satellite-difference technology is quickly realized by the method of joint calculations with multiple reference stations. The clock sequence is compared with the products provided by IGS (international global navigation satellite system service) analysis centers, and the influence of different station distributions and numbers of stations on the clock offset determination is also studied. The experimental results indicate that the real-time precise satellite clock products calculated by the proposed algorithm are equal to IGS final products. The estimation accuracy of relative satellite clock offsets can be achieved 0.08 ns, and their average standard deviation is 46.2 ps; the estimation error of satellite clock offsets is basically within 0.2 ns, and the average standard deviation is 73.2 ps. In addition, the spatial correlativity among tropospheric delay parameters can be effectively reduced by increasing the station spacing, and on the premise of ensuring the observation accuracy and computation speed, the clock estimation accuracy can be further enhanced by a reasonable increase in the number of stations. The algorithm has a smaller amount of arithmetic operations and a faster computation speed, and more accurate real-time satellite clock products can be quickly obtained with GPS carrier phase observations provided by only a small number of reference stations.