Satellite precise orbit determination with ionospheric-free strategy using triple-frequency observations

• Main Authors: ZENG Tian, SUI Lifen, RUAN Rengui, JIA Xiaolin, FENG Laiping
• Format: Article
• Language: zho
• Published: Surveying and Mapping Press 2020-10-01
• Series: Acta Geodaetica et Cartographica Sinica
• Subjects: precise orbit determination; triple-frequency; ambiguity resolution; ionospheric-free combination
• Online Access: http://xb.sinomaps.com/article/2020/1001-1595/2020-10-1275.htm
• ISSN: 1001-1595; 1001-1595

As the development of global navigation satellite system (GNSS), GNSS satellites transmitting multi-frequency signals has become a prevailing trend. However, recently the international GNSS service (IGS) analysis centers still use dual-frequency (DF) observations to derive the orbits, clocks and other products. The additional observations from the third frequency are not considered. We use two DF ionospheric-free (IF) combinations as the observation model, the improvements from the third frequency on orbits, clocks and station positions are assessed. In the carrier phase observation model, the satellite-dependent time-invariant and time-variant components are introduced. The two DF IF observation equations are re-parameterized to make the clock parameter aligned to the IGS clock products, and then the full-rank TF observation model is derived. Based on the strategy of building up extra wide lane, wide lane and narrow lane double-differenced ambiguities, the TF ambiguity resolution (AR) method is deduced. First taking 12 GPS Block IIF satellites as example, three precise orbit determination (POD) schemes, the L1/L2 DF IF POD (denoting as S1), the L1/L5 DF IF POD (denoting as S2), the L1/L2 and L1/L5 TF IF POD (denoting as S3), are processed in two station layouts. Results show that the S3 scheme in two station layouts can obtain the optimal precision. The orbit improvements of S3 with respect to S1 in cases of even and uneven distribution are within 10% and about 10%, respectively. The improvement of clocks RMS is slight, while STD is improved by 6.4% and 10.0%. The improved percentages of S3 vs. S2 are about less one times than that of S3 vs. S1, with the improved percentage of about 5%. Then the BDS-only POD test is processed and the orbits are validated by satellite laser ranging residuals. Results show that comparing with B1/B3 POD, the orbit and clock accuracy of TF POD can be improved. However, the improvement of TF POD comparing to B1/B2 POD is slight or even worse. The possible reason is the inaccuracy antenna phase values.