scholarly journals Doppler Differential Positioning Technology Using the BDS/GPS Indoor Array Pseudolite System

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4580 ◽  
Author(s):  
Gan ◽  
Yu ◽  
Huang ◽  
Jia ◽  
Zhang ◽  
...  
Keyword(s):  
Detection Method ◽  
Indoor Positioning ◽  
Cycle Slip ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Satellite Navigation System ◽  
Cycle Slips ◽  
Half Wavelength ◽  
Differential Positioning ◽  
Cycle Slip Detection

A Global Satellite Navigation System (GNSS) cannot provide normal location services in an indoor environment because the signals are blocked by buildings. The Beidou satellite navigation system (BDS)/GPS indoor array pseudolite system is proposed to overcome the problems of indoor positioning with conventional pseudolite, such as time synchronization, ambiguity resolution and base stations. At the same time, an algorithm for Doppler differential positioning is proposed to improve the indoor positioning accuracy and the positioning coverage of the system, which uses the Doppler difference equation and Known Point Initialization (KPI) to determinate the velocity and position of the receiver. Experiments were conducted to verify the proposed system under different conditions; the average positioning error of the Doppler differential positioning algorithm was 7.86 mm in the kinematic test and 2.9 mm in the static test. The results show that BDS/GPS indoor array pseudolite system has the potential to make indoor positioning achieve sub-centimeter precision. Finally, the positioning error of the proposed algorithm is also analyzed, and the data tests show that the dilution of precision (DOP) and cycle- slips have a significant impact on the indoor positioning accuracy; a cycle-slip of a half-wavelength can cause positioning errors of tens of millimeters. Therefore, the Doppler-aided cycle-slip detection method (DACS) is proposed to detect cycle-slips of one cycle or greater than one, and the carrier phase double difference cycle-slip detection method (CPDD) is used to detect cycle slips of a half-wavelength.

scholarly journals A New Fuzzy-Cluster-Based Cycle-Slip Detection Method for GPS Single-Frequency Observation

2019 ◽  
Vol 11 (24) ◽  
pp. 2896
Author(s):  
Zongnan Li ◽  
Min Li ◽  
Chuang Shi ◽  
Liang Chen ◽  
Chenlong Deng ◽  
...  
Keyword(s):  
Robust Estimation ◽  
Detection Rate ◽  
Detection Method ◽  
Estimation Method ◽  
Fuzzy Cluster ◽  
Correct Detection ◽  
Single Frequency ◽  
Cycle Slip ◽  
Cycle Slips ◽  
Cycle Slip Detection

The development of low-cost, small, modular receivers and their application in diverse scenarios with complex data quality has increased the requirements of single-frequency carrier-phase data preprocessing in real time. Different methods have been developed, but successful detection is not always ensured. The issue is crucial for high-precision positioning with Global Positioning System (GPS). Aiming at a high detection rate and low false-alarm rate, we propose a new cycle-slip detection method based on fuzzy-cluster. It consists of two steps. The first is identification of the epoch when cycle slips appear using Chi-square test based on time-differenced observations. The second is identification of the satellite which suffers from cycle slips using the fuzzy-cluster algorithm. To verify the performance of the proposed method, we compared it to a current robust method using real single-frequency data with simulated cycle slips. Results indicate that the proposed method outperforms the robust estimation method, with a higher correct-detection rate and lower undetection rate. As the number of satellites simulated with cycle slips increases, the correct-detection rate rapidly decreases from 100% to below 50% with the robust estimation method. While the correct-detection rate using the proposed method is always more than 60%, even if the number of satellites simulated with cycle slips reaches five. In addition, the proposed method always has a lower undetection rate than the robust estimation method. Simulation showed that when the number of satellites with cycle slips exceeds three, the undetection rate increases to more than 30%, reaching ~70% for the robust estimation method and less than 30% for the proposed method.

scholarly journals A Cycle Slip Repair Method Against Ionospheric Effects and Observational Noises for BDS Triple-Frequency Undifferenced Phases

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2819
Author(s):  
Dehai Li ◽  
Jinzhong Mi ◽  
Pengfei Cheng ◽  
Yunbin Yuan ◽  
Xingli Gan
Keyword(s):  
Detection Method ◽  
Satellite System ◽  
Ionospheric Delay ◽  
Observation Data ◽  
Cycle Slip ◽  
Cycle Slips ◽  
Triple Frequency ◽  
Cycle Slip Detection ◽  
Observational Noise ◽  
Slip Detection

The cycle slip detection (CSD) and cycle slip repair (CSR) are easily affected by ionospheric delay and observational noise. Aiming at mitigating the above disadvantage, a new BeiDou navigation satellite system (BDS) triple-frequency CSR method (BTCSR) is proposed for the undifferenced phase. BTCSR learns from the classic triple-frequency CSR (CTCSR), with combinations of phases and pseudoranges in correcting ionospheric delay and optimizing observational noise. Different from CTCSR, though, BTCSR has made the following improvements: (1) An optimal model of calculating cycle slip combination is established, which further takes into account the minimization of the effect of residual ionospheric error after the correction. The calculation of cycle slip combination is obtained with the root mean squared errors (0.0646, 0.1261, 0.1069) of cycles, resulting in CSR success rate of 99.9927%, and the wavelengths (4.8842,3.5738,8.1403) of m. (2) A discriminant function is added to guarantee the CSR correctness. This function utilizes epoch-difference value of the ionosphere-free and geometry-free phase to select the correct cycle slip value, which eliminates the interference of large pseudorange errors in determining the final cycle slip. Consequently, the performances of BTCSR and CTCSR have been compared. For the real BDS pseudorange observation with additional 1.5 m errors, which can cover situations of 99.96% pseudorange noise, results of CTCSR show failure, but results of BTCSR keep correct. Moreover, BTCSR has made the following improvements relative to the geometry-free cycle slip detection method (GFCSD) and Melboune–Wubbena cycle slip combination detection method (MWCSD): (1) During a moderate magnetic storm of level 6, CSR testing, with the BDS monitoring station in a low latitude region, showed that some failures occur in GFCSD because of severe ionospheric variation, but BTCSR could correctly identify and fix cycle slips. (2) For the BDS observation data with an additional 1.5 m error on the actual pseudoranges, MWCSD exhibited failures, but the repair results of BTCSR were correct and reliable. (3) For the special slips of (0,59,62) cycles, and equal slips of (1,1,1) cycles on (B1,B2,B3), that are hard to detect by GFCSD and MWCSD, respectively, BTCSR could repair these correctly. Finally, BTCSR obtains reliable repair results under large pseudorange errors and severe ionospheric variations, and the cut-off elevation larger than 10 degrees is the suggested background.

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.

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.

Effective Cycle Slip Detection and Identification for High Precision GPS/INS Integrated Systems

2003 ◽  
Vol 56 (3) ◽  
pp. 475-486 ◽  
Author(s):  
Hung-Kyu Lee ◽  
Jinling Wang ◽  
Chris Rizos
Keyword(s):  
Carrier Phase ◽  
Statistical Technique ◽  
Cycle Slip ◽  
Cusum Test ◽  
Mean Values ◽  
Phase Measurements ◽  
Additional Information ◽  
Cycle Slips ◽  
Detection And Identification ◽  
Cycle Slip Detection

To ensure high accuracy results from an integrated GPS/INS system, the carrier phase observables have to be used to update the filter's states. As a prerequisite the integer ambiguities must be resolved before using carrier phase measurements. However, a cycle slip that remains undetected (and uncorrected) will significantly degrade the filter's performance. In this paper, an algorithm that can effectively detect and identify any type of cycle slip is presented. The algorithm uses additional information provided by the INS, and applies a statistical technique known as the cumulative-sum (CUSUM) test. In this approach, cycle slip decision values can be computed from the INS-predicted position (due to the fact that its short-term accuracy is very high), and the CUSUM test used to detect cycle slips (as it is very sensitive to abrupt changes of mean values). Test results are presented to demonstrate the effectiveness of the proposed algorithm.

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.

scholarly journals The method of cycle-slip detection and repair GNSS meaturements by using receiver with high stability frequency oscillator

2019 ◽  
Vol 49 (3) ◽  
pp. 283-301 ◽  
Author(s):  
Nikolai S. Kosarev ◽  
Konstantin M. Antonovich ◽  
Leonid A. Lipatnikov
Keyword(s):  
High Stability ◽  
Moving Average ◽  
Measurement Data ◽  
Cycle Slip ◽  
Phase Measurements ◽  
Cycle Slips ◽  
Frequency Oscillator ◽  
Measurement Control ◽  
Cycle Slip Detection ◽  
Stability Frequency

Abstract A method of phase GNSS measurement control is described. The method is based on comparison of geometric range increments which are calculated using measurement data and approximate receiver coordinates and satellite navigation message position taking into account troposphere and ionosphere correction increments. Applicability of moving average for phase GNSS measurement control to detect the cycle slips and outliers is demonstrated. Test results of cycle slip detecting in phase measurements made by the receiver with high stability frequency oscillator are provided.

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 Optical Boundaries for LED-Based Indoor Positioning System

Computation ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 7 ◽  
Author(s):  
Olaoluwa Popoola ◽  
Sinan Sinanović ◽  
Wasiu Popoola ◽  
Roberto Ramirez-Iniguez
Keyword(s):  
Mathematical Model ◽  
Indoor Positioning ◽  
Experimental Measurements ◽  
Positioning System ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Light Emitting ◽  
Positioning Systems ◽  
Indoor Positioning System ◽  
Positioning Time

Overlap of footprints of light emitting diodes (LEDs) increases the positioning accuracy of wearable LED indoor positioning systems (IPS) but such an approach assumes that the footprint boundaries are defined. In this work, we develop a mathematical model for defining the footprint boundaries of an LED in terms of a threshold angle instead of the conventional half or full angle. To show the effect of the threshold angle, we compare how overlaps and receiver tilts affect the performance of an LED-based IPS when the optical boundary is defined at the threshold angle and at the full angle. Using experimental measurements, simulations, and theoretical analysis, the effect of the defined threshold angle is estimated. The results show that the positional time when using the newly defined threshold angle is 12 times shorter than the time when the full angle is used. When the effect of tilt is considered, the threshold angle time is 22 times shorter than the full angle positioning time. Regarding accuracy, it is shown in this work that a positioning error as low as 230 mm can be obtained. Consequently, while the IPS gives a very low positioning error, a defined threshold angle reduces delays in an overlap-based LED IPS.

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