Anomaly analysis of 18 years of newly merged GPS ephemeris from four IGS data centers

Wang, Haitao; Jiang, Hu; Jikun, OU; Sun, Binyong; Su, Zhong; Song, Muping; Guo, Aizhi

doi:10.1007/s10291-018-0791-1

Cited by 5 publications

(2 citation statements)

References 14 publications

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“…6. Calculate dρ s R,IF (t) and d∆ s R,m (t) according to Equations (17) and (18). After dρ s R,IF (t) and d∆ s R,m (t) are calculated, the reference receiver offsets are removed from them.…”

Section: The Second Step: Removing Receiver Clock Offsets Of Other Rementioning

confidence: 99%

“…The broadcast ephemeris is often used to create the a priori orbit [13], and the Bancroft algorithm is usually used to estimate the a priori orbit of newly launched satellites [14,15]. Unfortunately, although there are many corrections and checks in the process of generating and receiving a broadcasting ephemeris, it may still contain inaccurate information [16,17]. Besides, Earth's non-uniform gravity, other perceptual factors, and other issues could lead to an offset in the satellite location.…”

Section: Introductionmentioning

confidence: 99%

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A Three-Step Method for Determining Unhealthy Time Period of GPS Satellite Orbit in Broadcast Ephemeris and Its Preliminary Applications for Precise Orbit Determination

Yuan

Zhang

et al. 2019

Remote Sensing

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Abnormal information of satellite orbits inevitably appears in the broadcast ephemeris. Failure to obtain unhealthy information on GPS satellite orbits in precise orbit determination (POD) degrades GPS service performance. At present, the reliable unhealthy information published by the Center for Orbit Determination in Europe (CODE) is usually used, but it has at least one-day latency, and the current level of unhealthy information cannot fully meet the requirements of rapid and real-time geodetic applications, especially for non-IGS (International global navigation satellite systems (GNSS) Service) analysis centers and BeiDou navigation satellite system (BDS) users. Furthermore, the unhealthy orbit information detected by the traditional method, which is based on the synchronized pseudo-range residuals and regional observation network, cannot meet the requirement of setting separate sub-arcs in POD. In view of these problems, we propose a three-step method for determining unhealthy time periods of GPS satellite orbit in broadcast ephemeris during POD to provide reliable unhealthy information in near-real time. This method is a single-epoch solution, and it can detect unhealthy time periods in each sampling of observation in theory. It was subsequently used to detect unhealthy time periods for satellites G09 and G01 based on the 111 globally distributed tracking stations in the IGS. The performance of the new method was evaluated using cross-validation. Based on the test results, it detected an orbital leap for G09 in the broadcast ephemeris from 09:59:42 to 14:00:42 on 25 August 2017. Compared to the traditional method, the unhealthy start time using the three-step method was in better agreement with the information provided by CODE’s satellite crux files. G01 did not appear to have an orbital leap on the specified date, but it was misjudged by the traditional method. Furthermore, compared to the traditional method, the three-step method can perform unhealthy time period detection for a satellite all day long. In addition, precise orbit determination for unhealthy satellites is realized successfully with the unhealthy orbit arc information identified in this study. Compared to the CODE orbit, the root mean square and standard deviation of the new method for G09 are less than 2 cm, and the three-step method shows an improvement in accuracy compared with the traditional method. From the above results, it can be seen that this study can provide a feasible approach to meet the real-time unhealthy time period detection requirements of a satellite orbit in a broadcast ephemeris during POD. Furthermore, compared to waiting for updates of CODE’s satellite crux files or for accumulating delayed observation data, it has the potential to provide additional information in the process of generating ultra-rapid/real-time orbits.

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Section: The Second Step: Removing Receiver Clock Offsets Of Other Rementioning

confidence: 99%