scholarly journals A New Cycle Slip Detection and Repair Method Using a Single Receiver’s Single Station B1 and L1 Frequencies in Ground-Based Positioning Systems

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 346
Author(s):  
Xinyang Zhao ◽  
Zun Niu ◽  
Gaoxu Li ◽  
Qiangqiang Shuai ◽  
Bocheng Zhu
Keyword(s):  
Carrier Phase ◽  
Outdoor Environment ◽  
Cycle Slip ◽  
Dual Frequency ◽  
Positioning Systems ◽  
Cycle Slips ◽  
Single Station ◽  
Cycle Slip Detection ◽  
Phase Combination ◽  
Slip Detection

The detection and repair of the cycle slip is a key step for high precision navigation and positioning in indoor environments. Different methods have been developed to detect and repair cycle slips for carrier phase processing. However, most approaches are designed to eliminate the effects of the ionosphere in an outdoor environment, and many of them use pseudorange (code) information that is no longer suitable for indoor multipath environments. In this paper, a method based on the geometry-free combination without the pseudorange data is proposed to detect and fix cycle slips. A ground-based navigation system is built for data collection. Unlike the traditional dual-frequency cycle slip detection method, the Beidou B1, GPS L1 carrier phase combination is used instead of the B1, B2, or L1, L2 carrier phase combination, Ublox is used for data collecting. For fixing the cycle slips quickly, an improved adaptive Particle Swarm Optimization (PSO) algorithm is employed. We compared the performance of the new method with the existing two methods using simulated data in different conditions. The results show that the proposed method has better performance than other methods.

scholarly journals A Modified TurboEdit Cycle-Slip Detection and Correction Method for Dual-Frequency Smartphone GNSS Observation

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5756
Author(s):  
Xiaofei Xu ◽  
Zhixi Nie ◽  
Zhenjie Wang ◽  
Yuanfan Zhang
Keyword(s):  
Correction Method ◽  
Least Square ◽  
Cycle Slip ◽  
Dual Frequency ◽  
Cycle Slips ◽  
Small Cycle ◽  
Cycle Slip Detection ◽  
Gnss Receivers ◽  
Wide Lane ◽  
Slip Detection

Recently, some smartphone manufacturers have subsequently released dual-frequency GNSS smartphones. With dual-frequency observations, the positioning performance is expected to be significantly improved. Cycle-slip detection and correction play an important role in high-precision GNSS positioning, such as precise point positioning (PPP) and real-time kinematic (RTK) positioning. The TurboEdit method utilizes Melbourne–Wübbena (MW) and phase ionospheric residual (PIR) combinations to detect cycle-slips, and it is widely used in the data processing applications for geodetic GNSS receivers. The smartphone pseudorange observations are proved to be much noisier than those collected with geodetic GNSS receivers. Due to the poor pseudorange observation, the MW combination would be difficult to detect small cycle-slips. In addition, some specific cycle-slip combinations, where the ratio of cycle-slip values at different carrier frequencies is close to the frequency ratio, are also difficult to be detected by PIR combination. As a consequence, the traditional TurboEdit method may fail to detect specific small cycle-slip combinations. In this contribution, we develop a modified TurboEdit cycle-slip detection and correction method for dual-frequency smartphone GNSS observations. At first, MW and PIR combinations are adopted to detect cycle-slips by comparing these two combinations with moving-window average values. Then, the epoch-differenced wide-lane combinations are used to estimate the changes of smartphone position and clock bias, and the cycle-slip is identified by checking the largest normalized residual whether it exceeds a predefined threshold value. The process of estimation and cycle-slip identification is implemented in an iterative way until there is no over-limit residual or there is no redundant measurement. At last, the cycle-slip values at each frequency are estimated with the epoch-differenced wide-lane and ionosphere-free combinations, and the least-square ambiguity decorrelation adjustment (LAMBDA) method is adopted to further obtain an integer solution. The proposed method has been verified with 1 Hz dual-frequency smartphone GNSS data. The results show that the modified TurboEdit method can effectively detect and correct even for specific small cycle-slip combinations, e.g., (4, 3), which is difficult to be detected with the traditional TurboEdit method.

scholarly journals Cycle slip detection and repair for BeiDou-3 triple-frequency signals

2020 ◽  
Vol 17 (3) ◽  
pp. 172988142092640
Author(s):  
Xiangxiang Fan ◽  
Rui Tian ◽  
Xurong Dong ◽  
Weiyi Shuai ◽  
Youchen Fan
Keyword(s):  
Gaussian Noise ◽  
Detection Rate ◽  
Elevation Angle ◽  
Ionospheric Delay ◽  
Measurement Noise ◽  
Cycle Slip ◽  
Cycle Slips ◽  
Cycle Slip Detection ◽  
Phase Combination ◽  
Slip Detection

When carrier phase observations are applied to high-precision positioning, how to handle the cycle slip is an unavoidable problem. For cycle slip correction, detection combination noise and the ionospheric delay are two crucial factors. Specifically, the drastic changes in the ionosphere and the increased noise of code observations will increase the failure probability of cycle slip detection. To reduce the influence of code observation noise and ionospheric bias, a novel cycle slip detection method for BDS-3 satellites is proposed. Considering that code measurement noise is closely related to the satellite elevation angle, an elevation-based model is built to evaluate the code measurement noise. Firstly, two modified code-phase combinations are selected optimally based on 1% missed detection rate and 99% success detection rate to minimize the effects of code measurement noise. However, the second modified code-phase combination is more affected by ionospheric delay bias, so ionospheric bias of current epoch needs to be corrected. To reduce the influence of ionospheric bias, two moving windows of time-differenced ionospheric delay are introduced to correct the ionospheric bias of the second code-phase combination. Experiments with BeiDou-3 data are implemented in three different scenarios. To verify the effectiveness of the algorithm in the environment of high code observations noise, Gaussian noise is added to the code observations in the first scenario, and the results demonstrate that the success rate of cycle slip detection and repair is still greater than 95% when the standard deviation of Gaussian noise is 0.8 m. The second scenario is carried out under low ionospheric activity, and results indicate that the proposed method significantly reduces the times of failed detection and repair. Moreover, in the third scenario, BeiDou-3 data with cycle slips of different types under high ionospheric activity are tested, and all cycle slips can be correctly detected and corrected.

scholarly journals Cycle Slip Detection and Repair for Dual-Frequency LEO Satellite GPS Carrier Phase Observations with Orbit Dynamic Model Information

2019 ◽  
Vol 11 (11) ◽  
pp. 1273 ◽  
Author(s):  
Hui Wei ◽  
Jiancheng Li ◽  
Shoujian Zhang ◽  
Xinyu Xu
Keyword(s):  
Dynamic Model ◽  
Cycle Slip ◽  
Dual Frequency ◽  
Cycle Slips ◽  
Leo Satellites ◽  
Cycle Slip Detection ◽  
Orbit Dynamic ◽  
Leo Satellite ◽  
Gps Observations ◽  
Slip Detection

Cycle slip detection and repair are crucial for precise GPS-derived orbit determination of the low-Earth orbit (LEO) satellites. We present a new approach to detect and repair cycle slips for dual-frequency LEO satellite GPS observations. According to Newton’s equation of motion, the second-order time difference of the LEO satellite’s position (STP) is only related to the sampling interval and the satellite’s acceleration, which can be precisely obtained from the known orbit dynamic models. Then, several kinds of second-order time-difference geometry-free (STG) phase combinations, taking full advantage of the correlation between the satellite orbit variations and the dynamic model, with different level of ionospheric residuals, are proposed and adopted together to detect and fix cycle slips. The STG approach is tested with some LEO satellite GPS datasets. Results show that it is an effective cycle slip detection and repair method for LEO satellite GPS observations. This method also has some important features. Firstly, the STG combination is almost independent of the pseudorange. Secondly, this method is effective for LEO satellites, even in real-time application. Thirdly, this method is suitable for ground-based GPS receivers if we know the acceleration of the receivers.

scholarly journals Enhanced cycle slip detection method for dual-frequency BeiDou GEO carrier phase observations

GPS Solutions ◽  
2017 ◽  
Vol 21 (3) ◽  
pp. 1227-1238 ◽  
Author(s):  
Bing Ju ◽  
Defeng Gu ◽  
Xiao Chang ◽  
Thomas A. Herring ◽  
Xiaojun Duan ◽  
...  
Keyword(s):  
Carrier Phase ◽  
Detection Method ◽  
Cycle Slip ◽  
Dual Frequency ◽  
Cycle Slip Detection ◽  
Slip Detection

scholarly journals Algorithm for Real-Time Cycle Slip Detection and Repair for Low Elevation GPS Undifferenced Data in Different Environments

2021 ◽  
Vol 13 (11) ◽  
pp. 2078
Author(s):  
Ning Liu ◽  
Qin Zhang ◽  
Shuangcheng Zhang ◽  
Xiaoli Wu
Keyword(s):  
Real Time ◽  
High Voltage ◽  
Second Order ◽  
Cycle Slip ◽  
Order Difference ◽  
Cycle Slips ◽  
Cycle Slip Detection ◽  
Wide Lane ◽  
Time Cycle ◽  
Slip Detection

Real-time cycle slip detection and repair is one of the key issues in global positioning system (GPS) high precision data processing and application. In particular, when GPS stations are in special environments, such as strong ionospheric disturbance, sea, and high-voltage transmission line interference, cycle slip detection and repair in low elevation GPS observation data are more complicated than those in normal environments. For low elevation GPS undifferenced carrier phase data in different environments, a combined cycle slip detection algorithm is proposed. This method uses the first-order Gauss–Markov stochastic process to model the pseudorange multipath in the wide-lane phase minus narrow-lane pseudorange observation equation, and establishes the state equation of the wide-lane ambiguity with the pseudorange multipath as a parameter, and it uses the Kalman filter for real-time estimation and detects cycle slips based on statistical hypothesis testing with a predicted residual sequence. Meanwhile, considering there are certain correlations among low elevation, observation epoch interval, and ionospheric delay error, a second-order difference geometry-free combination cycle slip test is constructed that takes into account the elevation. By combining the two methods, real-time cycle slip detection for GPS low elevation satellite undifferenced data is achieved. A cycle slip repair method based on spatial search and objective function minimization criterion is further proposed to determine the correct solution of the cycle slips after they are detected. The whole algorithm is experimentally verified using the static and kinematic measured data of low elevation satellites under four different environments: normal condition, high-voltage transmission lines, dynamic condition in the sea, and ionospheric disturbances. The experimental results show that the algorithm can detect and repair cycle slips accurately for low elevation GPS undifferenced data, the difference between the float solution and the true value for the cycle slip does not exceed 0.5 cycle, and the differences obey the normal distribution overall. At the same time, the wide-lane ambiguity and second-order difference GF combination sequence calculated by the algorithm is smoother, which give further evidence that the algorithm for cycle slip detection and repair is feasible and effective, and has the advantage of being immune to the special observation environments.

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