| BDS-3 is independently developed by China and provides uninterrupted highprecision navigation,timing and positioning services all over the world.At present,BDS-3 broadcasts five types of csignals B1 C,B1I,B2 a,B2b and B3 I at three frequency points B1,B2 and B3 for civil application.Precise point positioning(PPP)is a satellite positioning technology that directly uses satellite signals to obtain the position of the receiver.It uses pseudo range and carrier phase observations through satellite broadcast signals,and the real-time precision products of satellite navigation system to obtain high-precision time and position services.PPP has become popular in the field of GNSS high-precision positioning because of its cost and implementation advantages.The development of BDS-3 high-precision positioning is inseparable from the research of PPP technology.Focusing on BDS-3 PPP technology,this paper has carried out the following research and innovation:(1)Aiming at the problem that the cycle slip of BDS-3 carrier phase observation affects the timing and positioning accuracy,a method to detect and repair BDS-3cycle slip is proposed in combination with MW and STPIR.This method is not severely affected by the signal sampling interval,and can effectively make up for the defect of cycle slip detection blind area of a single combination,and solve the multivalued problem of cycle slip repair of a single combination.This method is suitable for PPP signals without ionospheric combination.Based on this method,the carrier phase observations cycle slips of five public service signals of BDS-3 satellite navigation system are tested.The experimental results show that the combination of MW and stpir can accurately detect and repair the carrier phase cycle slip of five BDS-3 signals.(2)Aiming at the current situation of BDS-3’s broadcasting multi-frequency signals,the models of BDS-3 tri-frequency and quad-frequency PPP are studied.For ionospheric free combination,this paper analyzed the frequency interval of BDS-3signal,studied the DCB correction model of BDS-3 B1 I / B2 a and B1 C / B2 a,and applied it to BDS-3 tri-frequency and quad-frequency PPP.Using the observation data of 16 MEGX stations,the data of which includes at least quad-frequency BDS-3 signal observation data.According to the data,the results of BDS-3 B1 I / B3 I dualfrequency PPP,B1 I / B2 a / B3 I tri-frequency PPP and B1 I / B1 C / B2 a / B3 I quadfrequency PPP are analyzed.The analysis results show that the positioning performance of BDS-3 Tri-frequency PPP East / North / day can reach 1.1cm/0.9cm/2.0cm,and the positioning performance of BDS-3 quad-frequency PPP E/N/U can reach1.3cm/0.7cm/2.8cm,tri-frequency and quad-frequency PPP have the same positioning performance as dual-frequency PPP. |
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