【2025】A strategy to fast and precisely estimate IFCB products with a GPS/BDS-2 carrier-range network solution.

Inter-frequency clock bias (IFCB) products are crucial for GPS L1/L5 and BDS-2 B1/B2 precise point positioning with ambiguity resolution (PPP-AR). The computationally efficient epoch-differenced IFCBs are not adequately precise for PPP-AR, while generating precise IFCB products from the undifferenced uncombined network requires several hours. In this study, we proposed a strategy to fast and precisely estimate IFCB products with the carrier-range network solution. The epoch-differenced model was employed to estimate a priori IFCB products, instead of the undifferenced uncombined network solution. Then the IFCBs are re-estimated with carrier ranges, which come from PPP, reducing tens of thousands of ambiguity parameters and speeding up network solutions. GPS and BDS-2 multi-frequency data from 372 stations over 31 d in 2024 were archived for the IFCB estimation and performance evaluation. When 250 stations were used to estimate IFCB products, the processing only took 88 min. Compared with the undifferenced uncombined model, the proposed strategy saved 56.4% of the computational time. The root mean square (RMS) of the differences between estimated IFCBs and the benchmark IFCBs (i.e. GPS L1/L2 and L1/L5 clock offset differences) was 0.07 ns, matching the RMS of IFCBs from undifferenced uncombined network solution. For BDS-2, the RMS difference amounted to 0.02 ns. When these carrier-range IFCBs were used in PPP-AR instead of epoch-differenced IFCBs, the RMS of positioning errors for GPS L1/L5 static PPP-AR solutions improved from 7.0, 5.7, 15.6 mm to 2.7, 2.9, and 8.9 mm in the east, north and up directions, respectively, which is comparable to using IFCBs from undifferenced uncombined network solution. The mean narrow-lane ambiguity fixing rate improved by 20.6% for GPS and 9.9% for BDS-2. Therefore, this strategy enhances efficiency while guaranteeing the precision of the IFCBs, and can offer a rapid and precise IFCB product to support GPS L1/L5 and BDS-2 B1/B2 PPP-AR.

引用格式如下：

Qiyuan Zhang et al 2025 Meas. Sci. Technol. 36 056304 DOI 10.1088/1361-6501/adc9d2