Modification of Phase-Phase and Phase-Code Methods for Precise Detection and Prediction of GPS Cycle Slip Error

2015 ◽  
Vol 3 (4) ◽  
pp. 13-24 ◽  
Author(s):  
MA Yousef ◽  
AM Abdel-Hamid ◽  
AA Elashiry
Keyword(s):  
Cycle Slip ◽  
Phase Code ◽  
Phase Phase

scholarly journals Phase-Phase and Phase-Code Methods Modification for Precise Detecting and Predicting the GPS Cycle Slip Error

2015 ◽  
Vol 22 (1) ◽  
pp. 31-48
Author(s):  
Ahmed A. Elashiry ◽  
Mohamed A. Youssef ◽  
Mohamed A. Abdel Hamid
Keyword(s):  
Phase 1 ◽  
Local Oscillator ◽  
Low Noise ◽  
Least Square ◽  
Cycle Slip ◽  
Doppler Measurement ◽  
Cycle Slips ◽  
Phase Code ◽  
Code Bias ◽  
Phase Phase

Abstract There are three well-established detecting methods for cycle slip error, which are: Doppler measurement method, Phase-Code differencing method, and Phase-Phase Differencing Method. The first method depends on the comparison between observables and the fact that Doppler measurements are immune to cycle slip error. This method is considered as the most precise method for cycle slip detecting, because it succeed in detecting and predicting the smallest cycle slip size (1 cycle) in case the local oscillator has low bias. The second method depends on the comparison between observables (phase and code) and the code measurements are immune to the cycle slip error. But this method can’t detect or predict cycle slip size smaller than 10 cycles, because the code measurements have high noise. The third method depends on the comparison between observables (phase 1 and phase 2) and the phases measurements that have low noise. But this method can’t detect or predict cycle slip size smaller than 5 cycles, because the ionospheric change might have a high variation. For enhancing the precision of the last two methods in detecting the smallest cycle slip which size reaches 1 cycle, a new algorithm was developed in this research to determine the change in the ionospheric values and the code bias from epoch to epoch. That is done by solving all observables equations by least square technique. This modification on these methods succeed in detecting and predicting cycle slips of size of 1 cycle.

scholarly journals Optimizing Transmit Sequence and Instrumental Variables Receiver for Dual-Function Complexity System

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yu Yao ◽  
Junhui Zhao ◽  
Lenan Wu
Keyword(s):  
Approximate Solution ◽  
Instrumental Variables ◽  
Performance Index ◽  
Dual Function ◽  
Np Hard ◽  
Match Filter ◽  
Filter Output ◽  
Phase Code ◽  
Discrete Phase ◽  
Simulation Results

This correspondence deals with the joint cognitive design of transmit coded sequences and instrumental variables (IV) receive filter to enhance the performance of a dual-function radar-communication (DFRC) system in the presence of clutter disturbance. The IV receiver can reject clutter more efficiently than the match filter. The signal-to-clutter-and-noise ratio (SCNR) of the IV filter output is viewed as the performance index of the complexity system. We focus on phase only sequences, sharing both a continuous and a discrete phase code and develop optimization algorithms to achieve reasonable pairs of transmit coded sequences and IV receiver that fine approximate the behavior of the optimum SCNR. All iterations involve the solution of NP-hard quadratic fractional problems. The relaxation plus randomization technique is used to find an approximate solution. The complexity, corresponding to the operation of the proposed algorithms, depends on the number of acceptable iterations along with on and the complexity involved in all iterations. Simulation results are offered to evaluate the performance generated by the proposed scheme.

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 Three-phase phase-locked loop algorithms based on sliding modes

2021 ◽  
pp. 1-1
Author(s):  
Arnau Doria-Cerezo ◽  
Victor Repecho ◽  
Domingo Biel
Keyword(s):  
Phase Locked Loop ◽  
Sliding Modes ◽  
Three Phase ◽  
Phase Phase

Constant phase, phase drift, and phase entrainment in lasers with an injected signal

1990 ◽  
Vol 41 (11) ◽  
pp. 6470-6479 ◽  
Author(s):  
Peter A. Braza ◽  
Thomas Erneux
Keyword(s):  
Phase Drift ◽  
Phase Phase
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