Receiver clock jump and cycle slip correction algorithm for single-frequency GNSS receivers

Kinematic orbit determination (KOD) of low earth orbit (LEO) satellites only using single-frequency global navigation satellite system (GNSS) data is a suitable solution for space applications demanding meter-level orbit precision. For some small LEO satellites with the sun-pointing attitude mode, the rotation of the GNSS antenna radiation pattern changes the observation noise characteristics. Since the rotation angle information of the antenna plane may not be available for most low-cost missions, the true elevation cannot be computed and a general elevation-dependent weighting model remains invalid for the onboard GNSS observations. Furthermore, the low-stability GNSS receiver clock oscillator of the LEO satellite at high speeds makes single-frequency cycle slip detection ineffective and difficult since the clock steering events occur frequently. In this study, we investigated the improved KOD strategy to improve the performance of orbit solution using single-frequency GPS and BeiDou navigation satellite system (BDS) observations collected from the Luojia-1A satellite. The weighting model based on exponential function and signal strength is proposed according to the analysis of satellite attitude impact, and a joint single-frequency detection algorithm of receiver clock jump and cycle slip is investigated as well. Based on the GPS/BDS-combined KOD results, it is demonstrated that the clock jump and cycle slip can be properly detected and observations can be effectively utilized with the proposed weighting model considering satellite attitude, which significantly improves the availability and accuracy of orbit solution. The number of available epochs is increased by 12.9% benefitting from this strategy. The orbital root mean square (RMS) precision improvements in the radial, along-track, and cross-track directions are 22.1%, 16.4%, and 6.5%, respectively. Combining BDS observations also contributes to orbit precision improvement, which reaches up to 28.8%.

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An improved real-time cycle slip correction algorithm based on Doppler-aided signals for BDS triple-frequency measurements

Advances in Space Research ◽

10.1016/j.asr.2020.09.028 ◽

2021 ◽

Vol 67 (1) ◽

pp. 223-233

Author(s):

Xiao Gao ◽

Zhiqiang Yang ◽

Yuan Du ◽

Bing Yang

Keyword(s):

Real Time ◽

Cycle Slip ◽

Correction Algorithm ◽

Frequency Measurements ◽

Triple Frequency ◽

Time Cycle ◽

Cycle Slip Correction

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Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations

Journal of Applied Geodesy ◽

10.1515/jag-2019-0059 ◽

2020 ◽

Vol 14 (2) ◽

pp. 167-175

Author(s):

Li Zhang ◽

Volker Schwieger

Keyword(s):

Low Cost ◽

Ground Plane ◽

Single Frequency ◽

Spatial Correlations ◽

Raw Data ◽

Multipath Effect ◽

Temporal Correlations ◽

Multipath Effects ◽

Gnss Receivers ◽

Multipath Signals

AbstractThe investigations on low-cost single frequency GNSS receivers at the Institute of Engineering Geodesy (IIGS) show that u-blox GNSS receivers combined with low-cost antennas and self-constructed L1-optimized choke rings can reach an accuracy which almost meets the requirements of geodetic applications (see Zhang and Schwieger [25]). However, the quality (accuracy and reliability) of low-cost GNSS receiver data should still be improved, particularly in environments with obstructions. The multipath effects are a major error source for the short baselines. The ground plate or the choke ring ground plane can reduce the multipath signals from the horizontal reflector (e. g. ground). However, the shieldings cannot reduce the multipath signals from the vertical reflectors (e. g. walls).Because multipath effects are spatially and temporally correlated, an algorithm is developed for reducing the multipath effect by considering the spatial correlations of the adjoined stations (see Zhang and Schwieger [24]). In this paper, an algorithm based on the temporal correlations will be introduced. The developed algorithm is based on the periodic behavior of the estimated coordinates and not on carrier phase raw data, which is easy to use. Because, for the users, coordinates are more accessible than the raw data. The multipath effect can cause periodic oscillations but the periods change over time. Besides this, the multipath effect’s influence on the coordinates is a mixture of different multipath signals from different satellites and different reflectors. These two properties will be used to reduce the multipath effect. The algorithm runs in two steps and iteratively. Test measurements were carried out in a multipath intensive environment; the accuracies of the measurements are improved by about 50 % and the results can be delivered in near-real-time (in ca. 30 minutes), therefore the algorithm is suitable for structural health monitoring applications.

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The Effect of BDS-3 Time Group Delay and Differential Code Bias Corrections on Positioning

Applied Sciences ◽

10.3390/app11010104 ◽

2020 ◽

Vol 11 (1) ◽

pp. 104

Author(s):

Peipei Dai ◽

Jianping Xing ◽

Yulong Ge ◽

Xuhai Yang ◽

Weijin Qin ◽

...

Keyword(s):

Group Delay ◽

Assessment System ◽

Convergence Time ◽

Single Frequency ◽

Positioning Accuracy ◽

Differential Code Bias ◽

Receiver Clock ◽

Code Bias ◽

Point Positioning ◽

The Impact

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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Cycle Slip Detection and Correction Methods with Time-Differenced Model for Single Frequency GNSS Applications

Transactions of the Institute of Systems Control and Information Engineers ◽

10.5687/iscie.26.8 ◽

2013 ◽

Vol 26 (1) ◽

pp. 8-15 ◽

Cited By ~ 6

Author(s):

Seigo Fujita ◽

Susumu Saito ◽

Takayuki Yoshihara

Keyword(s):

Single Frequency ◽

Cycle Slip ◽

Cycle Slip Detection ◽

Slip Detection

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Cycle-slip detection and correction of GPS single-frequency carrier phase based on wavelet transform and LS-SVM

The Journal of Engineering ◽

10.1049/joe.2019.0525 ◽

2019 ◽

Vol 2019 (20) ◽

pp. 6995-6999

Author(s):

Xu Tu ◽

Zhang Lei

Keyword(s):

Wavelet Transform ◽

Carrier Phase ◽

Single Frequency ◽

Cycle Slip ◽

Cycle Slip Detection ◽

Slip Detection

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Robust INS/SFPPP-BDS tightly coupled navigation algorithm with adaptive cycle slip compensation model

Journal of Algorithms & Computational Technology ◽

10.1177/1748301819833044 ◽

2019 ◽

Vol 13 ◽

pp. 174830181983304

Author(s):

Hangshuai Ma ◽

Rong Wang ◽

Zhi Xiong ◽

Jianye Liu ◽

Chuanyi Li

Keyword(s):

Navigation System ◽

Carrier Phase ◽

Low Cost ◽

Integrated System ◽

Single Frequency ◽

Cycle Slip ◽

Phase Measurements ◽

Satellite Navigation System ◽

Tightly Coupled ◽

Robust Adaptive

The application of Beidou Satellite Navigation System (BDS) is developing rapidly. To satisfy the increasing demand for positioning performance, single-frequency precise point positioning (SFPPP) has been a focus in recent years. By introducing the SFPPP technique into the INS/BDS integrated system, higher navigation accuracy can be obtained. Cycle slip, which is caused by signal blockage during the measurement of the carrier phase, is a challenge for SFPPP application. In the INS/SFPPP-BDS integrated system, cycle slip can cause serious bias in BDS carrier phase measurements. In this paper, a new INS/SFBDS-PPP tightly coupled navigation system and a robust adaptive filtering method are proposed. Using a low-cost single-frequency receiver integrated with INS, an observation model was built based on the pseudo range and carrier phase by PPP preprocessing. The cycle slip was introduced into the state vector to improve the estimation precision. The test statistics, comprising the innovation and its covariance, were used to estimate the time at which cycle slip occurred and its amplitude to compensate for its effect on the observation. Finally, the proposed system model and algorithm are validated by simulation.

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