BDS Triple-frequency Ionospheric Delay and Code Hardware Delay Estimation Method

Getting precise undifferenced ambiguity resolution is the key issue when obtaining high-precise ionospheric delay with phase observations. Generally, extreme wide-lane (EWL), wide-lane (WL) and narrow-lane ambiguities are needed in the process under triple-frequency conditions. The MW combination wide-lane ambiguity may be fixed into a wrong integer because of the influence of code hardware delay and observation noise. In this paper BDS triple-frequency observation and GIM production are applied to resolve wide-lane ambiguity with a fixed EWL ambiguity and phase geometry-free (GF) combination. In addition, high-precise ionospheric delay is reconstructed and code hardware delay is separated. Test results show that the wide-lane ambiguity fixing success rate rises to 100% when assisted with GIM information, while the ambiguity is free of systemic bias. There is a difference of about 1.0m between the reconstructed ionospheric delay and GIM corrections, meaning an equivalent precision of 6 TECU. The standard deviation of the separated code hardware delay is less than 0.3 m.