Estimating and assessing Galileo navigation system satellite and receiver differential code biases using the ionospheric parameter and differential code bias joint estimation approach with multi-GNSS observations

The timing group delay parameter (TGD) or differential code bias parameter (DCB) is an important factor that affects the performance of GNSS basic services; therefore, TGD and DCB must be taken seriously. Moreover, the TGD parameter is modulated in the navigation message, taking into account the impact of TGD on the performance of the basic service. International GNSS Monitoring and Assessment System (iGMAS) provides the broadcast ephemeris with TGD parameter and the Chinese Academy of Science (CAS) provides DCB products. In this paper, the current available BDS-3 TGD and DCB parameters are firstly described in detail, and the relationship of TGD and DCB for BDS-3 is figured out. Then, correction models of BDS-3 TGD and DCB in standard point positioning (SPP) or precise point positioning (PPP) are given, which can be applied in various situations. For the effects of TGD and DCB in the SPP and PPP solution processes, all the signals from BDS-3 were researched, and the validity of TGD and DCB has been further verified. The experimental results show that the accuracy of B1I, B1C and B2a single-frequency SPP with TGD or DCB correction was improved by approximately 12–60%. TGD will not be considered for B3I single-frequency, because the broadcast satellite clock offset is based on the B3I as the reference signal. The positioning accuracy of B1I/B3I and B1C/B2a dual-frequency SPP showed that the improvement range for horizontal components is 60.2% to 74.4%, and the vertical components improved by about 50% after the modification of TGD and DCB. In addition, most of the uncorrected code biases are mostly absorbed into the receiver clock bias and other parameters for PPP, resulting in longer convergence time. The convergence time can be max increased by up to 50% when the DCB parameters are corrected. Consequently, the positioning accuracy can reach the centimeter level after convergence, but it is critical for PPP convergence time and receiver clock bias that the TGD and DCB correction be considered seriously.

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Estimation and Analysis of GNSS Differential Code Biases (DCBs) Using a Multi-Spacing Software Receiver

Sensors ◽

10.3390/s21020443 ◽

2021 ◽

Vol 21 (2) ◽

pp. 443

Author(s):

Ye Wang ◽

Lin Zhao ◽

Yang Gao

Keyword(s):

Primary Source ◽

Intermediate Frequency ◽

Global Navigation Satellite Systems ◽

Electron Content ◽

Software Receiver ◽

International Gnss Service ◽

Total Electron ◽

Satellite Systems ◽

Differential Code Biases ◽

Gnss Observations

In the use of global navigation satellite systems (GNSS) to monitor ionosphere variations by estimating total electron content (TEC), differential code biases (DCBs) in GNSS measurements are a primary source of errors. Satellite DCBs are currently estimated and broadcast to users by International GNSS Service (IGS) using a network of GNSS hardware receivers which are inside structure fixed. We propose an approach for satellite DCB estimation using a multi-spacing GNSS software receiver to analyze the influence of the correlator spacing on satellite DCB estimates and estimate satellite DCBs based on different correlator spacing observations from the software receiver. This software receiver-based approach is called multi-spacing DCB (MSDCB) estimation. In the software receiver approach, GNSS observations with different correlator spacings from intermediate frequency datasets can be generated. Since each correlator spacing allows the software receiver to output observations like a local GNSS receiver station, GNSS observations from different correlator spacings constitute a network of GNSS receivers, which makes it possible to use a single software receiver to estimate satellite DCBs. By comparing the MSDCBs to the IGS DCB products, the results show that the proposed correlator spacing flexible software receiver is able to predict satellite DCBs with increased flexibility and cost-effectiveness than the current hardware receiver-based DCB estimation approach.

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Estimation and analysis of GNSS receiver differential code bias in Southeast Asia using a new method

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/799/1/012023 ◽

2021 ◽

Vol 799 (1) ◽

pp. 012023

Author(s):

Qisheng Wang ◽

Shuanggen Jin ◽

Youjian Hu

Keyword(s):

Southeast Asia ◽

New Method ◽

Differential Code Bias ◽

Gnss Receiver ◽

Code Bias

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Performance Analysis of GPS/BDS Precise Point Positioning

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.713-715.1123 ◽

2015 ◽

Vol 713-715 ◽

pp. 1123-1126

Author(s):

Xiao Yu Li ◽

Jun Wang ◽

Ya Tao Liu

Keyword(s):

Precise Point Positioning ◽

Satellite Orbit ◽

Gps Measurements ◽

Differential Code Bias ◽

Phase Offset ◽

Antenna Phase ◽

Offset Correction ◽

Code Bias ◽

Point Positioning ◽

Processing Steps

Precise Point Positioning (PPP) with GPS measurements has achieved a level of success. In order to benefit from the multiple available constellations, research has been undertaken to combineGPS and BDS measurements in PPP processing.Mathematical models of GPS/BDS combined precise point positioning are introduced in this paper. GPS/BDS combined PPP models are developed based on the GPS-only PPP. The data pre-processing steps include applying satellite orbit and clock corrections, satellite antenna phase offset correction, receiver antenna phase offset correction, differential code bias corrections, troposphere delay corrections and the the Ionosphere-free observation combination is used. The results show that the positioning precision and convergence speed of GPS/BDS combined PPP are improved compared with GPS-only PPP.

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Assessment of BeiDou differential code bias variations from multi-GNSS network observations

Annales Geophysicae ◽

10.5194/angeo-34-259-2016 ◽

2016 ◽

Vol 34 (2) ◽

pp. 259-269 ◽

Cited By ~ 67

Author(s):

S. G. Jin ◽

R. Jin ◽

D. Li

Keyword(s):

Orbital Plane ◽

Satellite Orbit ◽

Satellite System ◽

Global Navigation Satellite Systems ◽

Dominant Factor ◽

Earth Orbit ◽

Navigation Satellite ◽

Differential Code Bias ◽

Code Bias ◽

Gnss Network

Abstract. The differential code bias (DCB) of global navigation satellite systems (GNSSs) affects precise ionospheric modeling and applications. In this paper, daily DCBs of the BeiDou Navigation Satellite System (BDS) are estimated and investigated from 2-year multi-GNSS network observations (2013–2014) based on global ionospheric maps (GIMs) from the Center for Orbit Determination in Europe (CODE), which are compared with Global Positioning System (GPS) results. The DCB of BDS satellites is a little less stable than GPS solutions, especially for geostationary Earth orbit (GEO) satellites. The BDS GEO observations decrease the precision of inclined geosynchronous satellite orbit (IGSO) and medium Earth orbit (MEO) DCB estimations. The RMS of BDS satellites DCB decreases to about 0.2 ns when we remove BDS GEO observations. Zero-mean condition effects are not the dominant factor for the higher RMS of BDS satellites DCB. Although there are no obvious secular variations in the DCB time series, sub-nanosecond variations are visible for both BDS and GPS satellites DCBs during 2013–2014. For satellites in the same orbital plane, their DCB variations have similar characteristics. In addition, variations in receivers DCB in the same region are found with a similar pattern between BDS and GPS. These variations in both GPS and BDS DCBs are mainly related to the estimated error from ionospheric variability, while the BDS DCB intrinsic variation is in sub-nanoseconds.

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