Performance analysis of GPS/Galileo/BDS three systems and all-frequency PPP-AR
-
摘要: 相位偏差的精确估计是实现精密单点定位(precise point positioning,PPP)非差模糊度固定 (ambiguity resolution,AR)的重要前提,但当前国际GNSS服务(International GNSS Service,IGS)分析中心 (analysis center,AC) 提供的相位偏差产品频率组合有限,使PPP-AR用户也只能使用相应频率的观测值,浪费了多频率的GNSS观测值. 为了实现基于任意GNSS频率选择和观测值组合灵活实现PPP-AR (即全频率PPP-AR) ,我们针对全球均匀分布的100多个 IGS测站1周的静态观测数据,估算全频率可观测相位偏差(observable specific signal bias,OSB),并使用开源PRIDE PPP-AR软件,进行静态PPP实验. 结果表明:伪距和相位OSB产品的平均标准差分别是0.25 ns和0.34 ns,满足PPP模糊度固定的需求. Galileo、北斗三号(BeiDou-3 Navigation Satellite System,BDS-3)频率自由组合时的平均模糊度固定率分别为(98.25%、96.74%)、(90.31%、91.64%),而北斗二号(BeiDou-2 Navigation Satellite System,BDS-2)的平均模糊度固定率为81.27%、86.02%. 定位精度和基准频率相比,E1/E6、G1/G5组合在三个方向上定位精度下降接近15%的. C2/C5组合在东(east,E)、北(north,N)方向上表现较好,但在天顶(up,U)方向上定位精度下降22.8%. GPS/Galileo/北斗卫星导航系统(BeiDou Navigation Satellite System,BDS)三个系统中其余参与测试的各频率组合包括C2/C7、C1/C5、C1/C6、C1/C7、E1/E7、E1/E8均呈现出较稳定的定位精度,各个频率组合的定位精度在E、N、U方向上的变化范围分别为5%、5%、15%,与基准频率相比没有较大的偏差,因而全频率PPP-AR已具备相当程度的可靠性. 全频率PPP-AR充分利用了多频率的GNSS观测值,相比使用基础频率的观测值实用价值更高;此外,全频率PPP-AR可以根据用户需求进行任意GNSS频率的选择和观测组合,从而更好地满足各种应用的需要.
-
关键词:
- 全频率PPP-AR /
- 北斗卫星导航系统 (BDS) /
- 观测信号偏差(OSB)
Abstract: The accurate estimation of phase biases is an essential prerequisite for achieving precise point positioning ambiguity resolution (PPP-AR). However, the phase bias products provided by the current International GNSS Service (IGS) analysis centers (ACs) are limited in terms of frequency combinations, which restricts PPP-AR users to using observations from corresponding frequencies only. This results in the underutilization of multi-frequency GNSS observations. In order to realize flexible PPP-AR based on arbitrary GNSS frequency selection and observation combinations (referred to as all-frequency PPP-AR), we conducted an analysis using static observation data from over 100 globally distributed IGS stations for a week. We estimated the observable phase biases (OSBs) for all available frequencies and conducted static precise point positioning experiments using the open-source PRIDE PPP-AR software. The results indicate that the average standard deviations of pseudo-range and phase OSB products are 0.25 ns and 0.34 ns, respectively, satisfying the requirements for PPP ambiguity fixing. The average ambiguity fixing rates for Galileo and BDS-3 frequency combinations are 98.25% and 96.74%, and 90.31% and 91.64%, respectively. For BDS-2, the average ambiguity fixing rates are 81.27% and 86.02%. Compared to the reference frequencies, the positioning accuracy decreases by nearly 15% in all three directions for E1/E6 and G1/G5 combinations. The C2/C5 combination performs well in the east (E) and north (N) directions but exhibits a 22.8% decrease in accuracy in the up (U) direction. In the testing of the GPS, Galileo, and BeiDou Navigation Satellite System (BDS), the remaining frequency combinations, including C2/C7, C1/C5, C1/C6, C1/C7, E1/E7, and E1/E8, all exhibited stable positioning accuracy. The positioning accuracy of each frequency combination varied by 5% in the E, 5% in the N, and 15% in the U direction, with no significant deviation compared to the reference frequency. Therefore, full-frequency PPP-AR has achieved a considerable degree of reliability. Full-frequency PPP-AR takes full advantage of the multi-frequency GNSS observations, offering higher practical value compared to using observations from the base frequency alone. Furthermore, full-frequency PPP-AR allows users to select and combine GNSS frequencies according to their specific requirements, thereby better satisfying the needs of various applications. -
表 1 数据处理策略
类别 处理策略 卫星系统与频率 GPS/Galileo/BDS 全频率 截至高度角 7° 采样率 2 Hz 定权方式 高度角定权 伪距OSB 武汉大学快速OSB产品 参考坐标 IGS周解 天线相位中心 Igs14.atx 对流层 Saastamoinen模型改正 电离层 无电离层组合 测站坐标 静态解,先验精度1 m 接收机钟差 逐历元解,白噪声模型 模糊度 每个弧段一个 -
[1] ZUMBERGE J F, HEFLIN M B, JEFFERSON D C, et al. Precise point positioning for the efficient and robust analysis of GPS data from large networks[J]. Journal of geophysical research, 1997, 102(B3): 5005-5017. DOI: 10.1029/96jb03860 [2] 张小红, 李星星, 李盼. GNSS精密单点定位技术及应用进展[J]. 测绘学报, 2017, 46(10): 1399-1407. DOI: 10.11947/j.AGCS.2017.20170327 [3] GE M R, GENDT G, ROTHACHER M, et al. Resolution of GPS carrier-phase ambiguities in precise point positioning (PPP) with daily observations[J]. Journal of geodesy, 2008, 82(7): 389-399. DOI: 10.1007/s00190-007-0187-4 [4] BANVILLE S, GENG J H, LOYER S, et al. On the interoperability of IGS products for precise point positioning with ambiguity resolution[J]. Journal of geodesy, 2020, 94(1): 10. DOI: 10.1007/s00190-019-01335-w [5] GENG J, CHEN X Y, PAN Y X, et al. A modified phase clock/bias model to improve PPP ambiguity resolution at Wuhan University[J]. Journal of geodesy, 2019(2): 1-15. DOI: 10.1007/s00190-019-01301-6 [6] LAURICHESSE D. Carrier-phase ambiguity resolution[J]. GPS world, 2015. [7] VILLIGER A , SCHAER S , DACH R , et al. Determination of GNSS pseudo-absolute code biases and their long-term combination[J]. Journal of geodesy, 2019, 93(9): 1487-1500. DOI: 10.1007/s00190-019-01262-w [8] LIU G, GUO F, WANG J, et al. Triple-frequency GPS un-differenced and uncombined PPP ambiguity resolution using observable-specific satellite signal biases[J]. Remote sensing, 2020, 12(14): 2310. DOI: 10.3390/rs12142310 [9] SCHAER S, VILLIGER A, ARNOLD D, et al. The CODE ambiguity-fixed clock and phase bias analysis products: generation, properties, and performance[J]. Journal of geodesy, 2021, 95(7): 81. DOI: 10.1007/s00190-021-01521-9 [10] GENG J H, WEN Q , ZHANG Q Y, et al. GNSS observable-specific phase biases for all-frequency PPP ambiguity resolution[J]. Journal of geodesy, 2022, 96(2): 11. DOI: 10.1007/s00190-022-01602-3 [11] WANG Z Y, WANG R G, WANG Y Y, et al. Modelling and assessment of a new triple-frequency IF1213 PPP with BDS/GPS[J]. Remote sensing, 2022, 14(18) : 4509-4509. DOI: 10.3390/rs14184509 [12] ODIJK D, ZHANG B C, KHODABANDEH A, et al. On the estimability of parameters in undifferenced, uncombined GNSS network and PPP-RTK user models by means of S-system theory[J]. Journal of geodesy, 2016, 90(1): 15-44. DOI: 10.1007/s00190-015-0854-9 [13] DONG D N, BOCK Y. Global Positioning System network analysis with phase ambiguity resolution applied to crustal deformation studies in California[J]. Journal of geophysical research solid earth, 1989, 94(B4): 3949-3966. DOI: 10.1029/JB094IB04P03949 [14] GENG J, ZHANG Q Y, LI G C, et al. Observable-specific phase biases of Wuhan multi-GNSS experiment analysis center’s rapid satellite products[J]. Satellite navigation, 2022, 3(1): 1-15 . DOI: 10.1186/s43020-022-00084-0