BDS-3/GNSS satellite ultra-rapid clock offsets estimation model with the aid of onboard clock states solution

doi:10.11947/j.AGCS.2024.20240112

Abstract

Abstract:

The orbit and clock offset of GNSS are the prerequisite for the high-performance positioning, navigation and timing (PNT) services. To overcome the obvious problems of clock offsets estimation in multi-GNSS ultra-rapid orbit determination solution, such as the observation quality and model configurations, an improved model to estimate ultra-rapid clock offset is proposed by considering the BDS-3/GNSS satellite clock states. Firstly, the observation equation of clock offset estimation by inserting the clock offset velocity and acceleration terms is constructed based on the fixed ultra-rapid orbit and station positions. Secondly, the algorithms of time-difference carrier phase (TDCP) and singular decomposition are used to construct the quality control and epoch-transition model of clock offset estimation. Thirdly, with the introduction of clock parameter states transition equation and consideration of BDS-3/GNSS onboard clock frequency stability, the single-epoch estimated clock offset can be obtained. According to the proposed BDS-3/GNSS ultra-rapid clock offset estimation method, an accuracy improvement at least 46.9% can be obtained, where the instantaneous clock offset of epoch interval can be directly derived using the clock state values. In addition, compared with the traditionally issued BDS-3/GNSS ultra-rapid clock offsets, the four-system kinematics PPP performances of positioning and convergence are improved with 1.7%, 6.0%, 31.2% and 44.9%, 33.3%, 38.9% for E, N and U directions, respectively. Meanwhile, the accuracy of the predicted clock offset is also improved, which can lead to the decreasing of four-system static PPP positioning residuals and convergence time with 6.3%, 13.5%, 11.3% and 14.5%, 1.6%, 12.4% for E, N and U directions, respectively. Therefore, the quality of BDS-3/GNSS satellite ultra-rapid clock offset is significantly improved by the proposed estimation method, which can also be used to improve the multi-GNSS constellation performances of real-time and near-real-time services.

Key words: BDS-3/GNSS, satellite ultra-rapid clock offset, time-difference carrier phase, clock offset states, quality control

CLC Number:

P228

Chao HU, Qianxin WANG. BDS-3/GNSS satellite ultra-rapid clock offsets estimation model with the aid of onboard clock states solution[J]. Acta Geodaetica et Cartographica Sinica, 2024, 53(12): 2268-2281.

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参数或模型	配置
卫星系统	BDS-3+GPS+Galileo+GLONASS
观测模型	双频无电离层组合
测站数	60
待估参数	轨道、钟差、站坐标、系统偏差、接收机钟差、ERP
轨道参数	初始状态、光压
钟差模型	白噪声
截止高度角/（°）	7
定轨弧长	24 h解算+24 h预报
采样间隔/s	300
定权策略	E>30°P=1，E≤30°P=1/2sin（E），E为高度角
PCO与PCV	igs14.atx
模糊度	固定解
卫星姿态模型	BDS-3参考文献[8]
重力场	EGM 2008
固体潮模型	IERS 2010
相对论效应	IERS 2010

卫星系统	模型一/ns	模型二/ns	提升率/（%）
GPS	0.130	0.069	46.9
GLONASS	0.349	0.184	47.3
Galileo	0.248	0.098	60.5
BDS-3	0.249	0.103	58.6

卫星系统或原子钟类型	μ				σ
卫星系统或原子钟类型	5 s加密	15 s加密	30估计	30 s内插	5 s加密	15 s加密	30估计	30 s内插
GPS	6.63×10^-5	3.17×10^-5	2.37×10^-5	-2.40×10^-3	3.35×10^-2	4.99×10^-2	8.65×10^-2	1.25×10^-1
GLONASS	1.38×10^-4	4.92×10^-5	3.22×10^-5	8.78×10^-4	2.07×10^-2	2.91×10^-2	4.21×10^-2	1.25×10^-1
Galileo	6.86×10^-5	4.99×10^-5	-5.22×10^-6	1.27×10^-4	6.17×10^-3	6.68×10^-3	8.55×10^-3	1.69×10^-2
BDS-3	3.91×10^-5	1.20×10^-5	-2.41×10^-5	-2.34×10^-4	7.21×10^-3	9.78×10^-3	1.14×10^-2	1.53×10^-2
Rb	9.42×10^-5	6.62×10^-5	4.44×10^-5	9.14×10^-4	2.88×10^-2	3.56×10^-2	9.55×10^-2	2.12×10^-1
Cs	7.26×10^-5	5.46×10^-5	-5.78×10^-5	3.67×10^-4	9.43×10^-3	1.22×10^-2	1.67×10^-2	1.11×10^-1
PHM	2.23×10^-5	3.31×10^-5	3.33×10^-5	-1.68×10^-4	6.44×10^-3	7.36×10^-3	8.65×10^-3	2.22×10^-2

	PPP方案	定位精度/cm			收敛时间/min
	PPP方案	E	N	U	E	N	U
BDS-3	5 min超快速钟差	3.79	2.69	5.86	49.5	36	59.5
	30 s估计钟差	2.76	2.44	5.16	44.0	32.5	50.0
	提升率/（%）	27.2	9.3	11.9	11.1	9.7	16.0
	5 min钟差+状态	2.64	2.50	5.22	45.5	30.5	48.5
	提升率/（%）	30.3	7.1	10.9	8.1	15.3	18.5
	30 s WUM钟差	1.41	0.96	3.21	22	26.5	25.0
BDS-3+GPS	5 min超快速钟差	2.98	2.62	5.56	45.5	32.0	55.0
	30 s估计钟差	2.61	1.68	4.99	34.5	29.0	42.5
	提升率/（%）	12.4	35.9	10.3	24.2	9.4	22.7
	5 min钟差+状态	2.66	1.98	5.21	38.5	27.5	44.0
	提升率/（%）	10.7	24.4	6.3	15.4	14.1	20.0
	30 s WUM钟差	1.16	0.93	2.38	19.5	20.0	20.5
四系统	5 min超快速钟差	2.37	1.99	2.05	39.0	27.0	36.0
	30 s估计钟差	2.33	1.87	1.41	21.5	18.0	22.0
	提升率/（%）	1.7	6.0	31.2	44.9	33.3	38.9
	5 min钟差+状态	2.33	1.86	1.52	23.5	17.5	24.0
	提升率/（%）30 s WUM钟差	1.70.81	6.5 0.51	25.9 1.01	39.7 17.0	35.2 9.0	33.3 19.5

原子钟类型	千分秒稳定性	万分秒稳定性
Rb	5.12	15.18
Cs	2.88	11.25
PHM	1.14	2.36