The phase and code biases of Galileo and BDS-3 BOC signals: effect on ambiguity resolution and precise positioning

Li, Xingxing; Li, Xin; Liu, Gege; Xie, Weiliang; Guo, Fei; Yuan, Yongqiang; Zhang, Keke; Feng, Guolong

doi:10.1007/s00190-019-01336-9

Cited by 29 publications

(12 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Equation ( 3)), and due to the magnitude of the coefficient (µ j − µ 1 )/(µ 2 − µ 1 ) of one of them that is close to the value one for these frequencies, one may reasonably conclude that the absolute satellite code biases on E5a, E5b and E5 are almost identical. As a result, the satellite DCBs between E5b and E5 signals are almost zero, as also shown in Li et al [50]. The only exception to this case is satellite E24, for which a code bias of larger magnitude is seen, while high differential biases have also been reported earlier in Ammar et al [51].…”

Section: Network Correctionssupporting

confidence: 80%

“…These corrections consist of the satellite clocks, satellite phase (SPBs) and code biases (SCBs). We chose to determine the estimable code biases, rather than obtaining DCBs from an external source as in Li et al [50], in order to have a consistent estimation of the highly correlated PPP-RTK corrections. Based on our observation model and chosen S-basis (cf.…”

Section: Network Correctionsmentioning

confidence: 99%

See 1 more Smart Citation

A Multi-Frequency Galileo PPP-RTK Convergence Analysis with an Emphasis on the Role of Frequency Spacing

2021

View full text Add to dashboard Cite

The single-receiver integer ambiguity resolution-enabled variant of precise point positioning (PPP), namely PPP-RTK, has proven to be crucial in reducing the long convergence time of PPP solutions through the recovery of the integerness of the user-ambiguities. The proliferation of global navigation satellite systems (GNSS) supports various improvements in this regard through the availability of more satellites and frequencies. The increased availability of the Galileo E6 signal from GNSS receivers paves the way for speeding up integer ambiguity resolution, as more frequencies provide for a stronger model. In this contribution, the Galileo-based PPP-RTK ambiguity resolution and positioning convergence capabilities are studied and numerically demonstrated as a function of the number and spacing of frequencies, aiming to shed light on which frequencies should be used to obtain optimal performance. Through a formal analysis, we provide insight into the pivotal role of frequency separation in ambiguity resolution. Using real Galileo data on up to five frequencies and our estimated PPP-RTK corrections, representative kinematic user convergence results with partial ambiguity resolution are presented and discussed. Compared to the achieved performance of dual-frequency fixed solutions, it is found that the contribution of multi-frequency observations is significant and largely driven by frequency separation. When using all five available frequencies, it is shown that the kinematic user can achieve a sub-decimeter level convergence in 15.0 min (90% percentile). In our analysis, we also show to what extent the provision of the estimable satellite code biases as standard PPP-RTK corrections accelerates convergence. Finally, we numerically demonstrate that, when integrated with GPS, the kinematic user solution achieves convergence in 3.0 and 5.0 min on average and at 90%, respectively, in the presence of ionospheric delays, thereby indicating the single-receiver user’s fast-convergence capabilities.

show abstract

Section: Network Correctionssupporting

confidence: 80%

Section: Network Correctionsmentioning

confidence: 99%

A Multi-Frequency Galileo PPP-RTK Convergence Analysis with an Emphasis on the Role of Frequency Spacing

2021

View full text Add to dashboard Cite

show abstract

“…1), it is reasonable to assume that the independent PIFCB variations for all BDS-3 satellites equal zero. This was also demonstrated through PIFCB variation from frequencies B1I, B2a and B2b reported by Li et al (2020).…”

Section: Model Implementation Using Bds-2 and Bds-3 Multi-frequency Datasupporting

confidence: 63%

GNSS satellite inter-frequency clock bias estimation and correction based on IGS clock datum: a unified model and result validation using BDS-2 and BDS-3 multi-frequency data

Fan

Wang

Guo

et al. 2021

J Geod

View full text Add to dashboard Cite

To deal with inconsistency between Global Navigation Satellite System (GNSS) multi-frequency data and International GNSS Service (IGS) clock product, we propose a unified model for GNSS satellite inter-frequency clock bias (IFCB) estimation and correction based on the IGS clock datum. The proposed model is rigorously derived by three sequential steps. First, by means of accurate modeling of the time-variant part of satellite phase-based IFCB (PIFCB) and introducing a zero-mean condition for satellite code-based IFCB (CIFCB), a set of independent satellite IFCBs are estimated in a full-rank multi-frequency uncombined model where IGS orbit and clock products are taken as input. The independent satellite IFCB refers to hardware delay difference between a specified frequency and two reference frequencies that are used for generating the IGS product. In the second step, a linear equation between satellite IFCBs from any three frequencies and the independent satellite IFCB estimates is derived. Based on this equation, the third step aims to establish a general satellite IFCB correction model which is used to align data on any two frequencies to the IGS clocks. The proposed model is implemented and validated using one month of multi-frequency data from BeiDou regional system (BDS-2) and BeiDou global system (BDS-3), i.e., B1I, B2I, B3I, B1C, B2a and B2b. By choosing B1I and B3I as reference frequencies, periodic analysis results suggest that a second-order periodic function is suitable for modeling BDS-2 independent satellite PIFCB variations. Yet there is no need to introduce periodic function into BDS-3 independent satellite PIFCB variations at all frequencies. For observation types of 1X (B1C), 5X (B2a) and 7Z (B2b), the standard deviation (STD) of three independent CIFCB estimates at each BDS-3 new frequency (i.e., B1C, B2a and B2b) and one CIFCB from the three new frequencies for all BDS-3 satellites are 3.14, 0.09, 0.12 and 0.09 ns, while those for the observation types of 1P (B1C), 5P (B2a) and 7D (B2b) are 2.52, 0.08, 0.08 and 0.04 ns, respectively. A major reason for the large noise of the independent satellite CIFCB at frequency B1C is that the frequency value of B1C is very close to that of B1I. Using the satellite IFCB estimates as corrections, the average RMS of kinematic precise point positioning (PPP) errors using ionosphere-free combination of BDS-3 multi-frequency data is 2.7 and 5.0 cm on horizontal and up directions, respectively, showing a same level with that of B1I/B3I-based PPP. In comparison, the accuracy of PPP is decreased by several millimeters during convergence when the differential code bias (DCB) product is used for correction. Keywords BDS-2 • BDS-3 • Inter-frequency clock bias • Multi-frequency • Uncombined model • Differential code bias B Cheng Wang

show abstract

“…In their study, the multi-constellation Global Navigation Satellite System (GNSS) PPP presented faster solution convergence and higher positioning accuracy than single-system PPP. Recently, the investigation of multi-GNSS PPP data processing is not only about the dual-frequency models (Cai et al 2015), but also focusing on the multi-frequency observations (Li et al 2019b(Li et al , 2020a. Briefly, the multi-frequency and multi-GNSS based PPP is becoming increasingly fashionable for precise positioning services (Alkan and Öcalan 2013; Guo et al 2018), particularly in some new applications such as self-driving cars and unmanned aerial vehicles (Nie et al 2019;Geng and Guo 2020).…”

Section: Introductionmentioning

confidence: 99%

Semi-tightly coupled integration of multi-GNSS PPP and S-VINS for precise positioning in GNSS-challenged environments

et al. 2021

Self Cite

View full text Add to dashboard Cite

Because of its high-precision, low-cost and easy-operation, Precise Point Positioning (PPP) becomes a potential and attractive positioning technique that can be applied to self-driving cars and drones. However, the reliability and availability of PPP will be significantly degraded in the extremely difficult conditions where Global Navigation Satellite System (GNSS) signals are blocked frequently. Inertial Navigation System (INS) has been integrated with GNSS to ameliorate such situations in the last decades. Recently, the Visual-Inertial Navigation Systems (VINS) with favorable complementary characteristics is demonstrated to realize a more stable and accurate local position estimation than the INS-only. Nevertheless, the system still must rely on the global positions to eliminate the accumulated errors. In this contribution, we present a semi-tight coupling framework of multi-GNSS PPP and Stereo VINS (S-VINS), which achieves the bidirectional location transfer and sharing in two separate navigation systems. In our approach, the local positions, produced by S-VINS are integrated with multi-GNSS PPP through a graph-optimization based method. Furthermore, the accurate forecast positions with S-VINS are fed back to assist PPP in GNSS-challenged environments. The statistical analysis of a GNSS outage simulation test shows that the S-VINS mode can effectively suppress the degradation of positioning accuracy compared with the INS-only mode. We also carried out a vehicle-borne experiment collecting multi-sensor data in a GNSS-challenged environment. For the complex driving environment, the PPP positioning capability is significantly improved with the aiding of S-VINS. The 3D positioning accuracy is improved by 49.0% for Global Positioning System (GPS), 40.3% for GPS + GLOANSS (Global Navigation Satellite System), 45.6% for GPS + BDS (BeiDou navigation satellite System), and 51.2% for GPS + GLONASS + BDS. On this basis, the solution with the semi-tight coupling scheme of multi-GNSS PPP/S-VINS achieves the improvements of 41.8–60.6% in 3D positioning accuracy compared with the multi-GNSS PPP/INS solutions.

show abstract

The phase and code biases of Galileo and BDS-3 BOC signals: effect on ambiguity resolution and precise positioning

Cited by 29 publications

References 25 publications

A Multi-Frequency Galileo PPP-RTK Convergence Analysis with an Emphasis on the Role of Frequency Spacing

A Multi-Frequency Galileo PPP-RTK Convergence Analysis with an Emphasis on the Role of Frequency Spacing

GNSS satellite inter-frequency clock bias estimation and correction based on IGS clock datum: a unified model and result validation using BDS-2 and BDS-3 multi-frequency data

Semi-tightly coupled integration of multi-GNSS PPP and S-VINS for precise positioning in GNSS-challenged environments

Contact Info

Product

Resources

About