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 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.

A New Cycle Slip Detection and Repair Method for Single-Frequency GNSS Data

2018 ◽  
Vol 71 (6) ◽  
pp. 1492-1510 ◽  
Author(s):  
Qusen Chen ◽  
Hua Chen ◽  
Weiping Jiang ◽  
Xiaohui Zhou ◽  
Peng Yuan
Keyword(s):  
Satellite System ◽  
Single Frequency ◽  
Half Cycle ◽  
Cycle Slip ◽  
Cycle Slips ◽  
Small Cycle ◽  
Cycle Slip Detection ◽  
Gnss Data ◽  
The Impact ◽  
Slip Detection

Cycle slip detection for single frequency Global Navigation Satellite System (GNSS) data is currently mainly based on measurement modelling or prediction, which cannot be effectively performed for kinematic applications and it is difficult to detect or repair small cycle slips such as half-cycle slips. In this paper, a new method that is based on the total differential of ambiguity and Least-Squares Adjustment (LSA) for cycle slip detection and repair is introduced and validated. This method utilises only carrier-phase observations to build an ambiguity function. LSA is then conducted for detecting and repairing cycle slips, where the coordinate and cycle slips are obtained successively. The performance of this method is assessed through processing short and long baselines in static and kinematic modes and the impact of linearization and atmospheric errors are analysed at the same time under a controlled variable method. The results indicate this method is very effective and reliable in detecting and repairing multiple cycle slips, especially small cycle slips.

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 Ionosphere-Constrained Triple-Frequency Cycle Slip Fixing Method for the Rapid Re-Initialization of PPP

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 117 ◽  
Author(s):  
Fuxin Yang ◽  
Lin Zhao ◽  
Liang Li ◽  
Jianhua Cheng ◽  
Jie Zhang
Keyword(s):  
Ionospheric Delay ◽  
Cycle Slip ◽  
Frequency Diversity ◽  
Cycle Slips ◽  
Triple Frequency ◽  
Cycle Slip Detection ◽  
Wide Lane ◽  
Data Gap ◽  
The Impact ◽  
Slip Detection

The re-initialization of precise point positioning (PPP) can be avoided by cycle slip detection and correction. Ionospheric delay is critical for cycle slip detection and correction, especially for a long data gap. The frequency diversity from GNSS modernization provides the potential for mitigating the impact of ionospheric delay on cycle slip detection and correction. The proposed method constructs the extra-wide lane (EWL), the wide lane (WL), and the narrow lane (NL) epoch-differenced linear combinations based on the ionosphere constrain criterion, so as to determine the undifferenced cycle slips from the cascading ambiguity resolution. The experiment results show that the cycle slips can be fixed correctly even though cycle slips occur in all the available carrier phase observations, and the 3 min data gaps can be merged without high precision positioning continuity loss. The kinematic experiment shows that the instantaneous re-initialization can be achieved with the proposed method.

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 Effective Cycle Slip Detection and Repair for PPP/INS Integrated Systems

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 502 ◽  
Author(s):  
Sheng Yang ◽  
Leilei Li ◽  
Jingbin Liu ◽  
Qusen Chen ◽  
Xuewen Ding ◽  
...  
Keyword(s):  
Integrated Systems ◽  
Detection Accuracy ◽  
Cycle Slip ◽  
Long Wavelength ◽  
Cycle Slips ◽  
Vehicle Data ◽  
Global Positioning ◽  
Long Time ◽  
Cycle Slip Detection ◽  
Wide Lane

Cycle slip (CS) is a primary error source in Precise Point Positioning/Inertial Navigation System (PPP/INS) integrated systems. In this study, an INS-aided CS detection and repair method is presented. It utilizes high-precision INS information instead of a pseudorange to remove the satellite–receiver geometric range in the wide-lane (WL) and ionospheric-free (IF) phase combinations and creates an INS-aided WL (WL-INS) model and an INS-aided IF (IF-INS) model. Since INS information is superior to pseudorange, the INS-aided models have high detection accuracy. However, the effectiveness of INS-aided models cannot persist for a long time because of INS accumulation error. To overcome the disturbance of INS error, improved INS-aided models are proposed. This idea takes advantage of the long wavelength of WL combination and tries to fix WL CS. Once it succeeds, the INS error can be evaluated and removed. The proposed method was tested using land vehicle data, in which simulated cycle slips and signal interruption were introduced. The results show that this method can accurately detect and repair different cycle slips between the continuous Global Positioning System (GPS) epoch. When it comes to the cycle slip after a GPS interruption, the method can also accelerate PPP re-convergence, as it is not affected by the inertial accumulation error.

scholarly journals Instantaneous Triple-Frequency GPS Cycle-Slip Detection and Repair

2009 ◽  
Vol 2009 ◽  
pp. 1-15 ◽  
Author(s):  
Zhen Dai ◽  
Stefan Knedlik ◽  
Otmar Loffeld
Keyword(s):  
Time Algorithm ◽  
Cycle Slip ◽  
High Data ◽  
Cycle Slips ◽  
Triple Frequency ◽  
Test Criteria ◽  
Cycle Slip Detection ◽  
Phase Data ◽  
Low Phase Noise ◽  
Slip Detection

A real-time algorithm to detect, determine, and validate the cycle-slips for triple-frequency GPS is proposed. The cycle-slip detection is implemented by simultaneously applying two geometry-free phase combinations in order to detect more insensitive cycle-slips, and it is applicable for high data rate applications. The cycle-slip determination adaptively uses the predicted phase data and the code data. LAMBDA technique is applied to search for the cycle-slip candidates. The cycle-slip validation provides strict test criteria to identify the cycle-slip candidates under low phase noise. The reliability of the proposed algorithms is tested in different simulated scenarios.

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