scholarly journals Design and Validation of a Cascading Vector Tracking Loop in High Dynamic Environments

2021 ◽  
Vol 13 (10) ◽  
pp. 2000
Author(s):  
Zhiyong Tu ◽  
Yidong Lou ◽  
Wenfei Guo ◽  
Weiwei Song ◽  
Yusheng Wang
Keyword(s):  
Unscented Kalman Filter ◽  
Negative Impact ◽  
Dynamic Performance ◽  
Phase Error ◽  
Tracking Error ◽  
Doppler Frequency ◽  
Convergence Time ◽  
Tracking Loop ◽  
Vector Tracking ◽  
High Dynamic

This paper designs a cascading vector tracking loop based on the Unscented Kalman Filter (UKF) for high dynamic environment. Constant improvement in dynamic performance is an enormous challenge to the traditional receiver. Due to the doppler effect, the satellite signals received by these vehicles contain fast changing doppler frequency shifts and the first and second derivatives of doppler frequency, which will directly cause a negative impact on the receiver’s stable tracking of the signals. In order to guarantee the dynamic performance and the tracking accuracy, this paper designs a vector carrier structure to estimate the doppler component of a signal. Firstly, after the coherence integral, the IQ values are reorganized into new observations. Secondly, the phase error and frequency of the carrier are estimated through the pre-filter. Then, the pseudorange and carrier frequency are used as the observations of the main filter to estimate the motion state of the aircraft. Finally, the current state is fed back to the carrier Numerical Controlled Oscillator (NCO) as a complete closed loop. In the whole structure, the cascading vector loop replaces the original carrier tracking loop, and the stable signal tracking of code loop is guaranteed by carrier assisted pseudo-code method. In this paper, with the high dynamic signals generated by the GNSS signal simulator, this designed algorithm is validated by a software receiver. The results show that this loop has a wider dynamic tracking range and lower tracking error than the second-order frequency locked loop assisted third-order phase locked loop in high dynamic circumstances. When the acceleration of carrier is 100 g, the convergence time of vector structure is about 100 ms, and the carrier phase error is lower than 0.6 mm.

Combined Tracking Strategy Based on Unscented Kalman Filter for Global Positioning System L2C CM/CL Signal

2015 ◽  
Vol 65 (5) ◽  
pp. 395 ◽  
Author(s):  
Xuefen Zhu ◽  
Fei Shen ◽  
Jianfeng Chen ◽  
Yang Yang ◽  
Dongrui Yang ◽  
...  
Keyword(s):  
Kalman Filter ◽  
Global Positioning System ◽  
Unscented Kalman Filter ◽  
Dominant Role ◽  
Tracking Error ◽  
Doppler Frequency ◽  
Positioning System ◽  
Tracking Loop ◽  
Signal Tracking ◽  
Global Positioning

<p>In a global positioning system receiver, the tracking algorithm plays a dominant role since the code delay and Doppler frequency shift need to be accurately estimated as well as their variation over time need to be continuously updated. Combine unscented Kalman filter (UKF) with CM/CL signal to improve the signal tracking precision is proposed. It allow weighting assignment between CM code and CL code incoming signal, masked by a mass of noise, and to describe a UKF tracking loop aiming at decreasing numerical errors. UKF here involves state and measuring equations which calculate absolute offsets to adjust initial code and carrier phase then dramatically decrease the tracking error. In particular, the algorithm is implemented in both open space and jammed environment to highlight the advantages of tracking approach, by comparing single code and combined code, UKF and EKF tracking loop. It proves that signal tracking based on UKF, with low energy dissipation as well as high precision, is particularly appealing for a software receiver implementation.</p>

A Novel GNSS Carrier Tracking Loop Design Based on Fuzzy Logical Control

2011 ◽  
Vol 130-134 ◽  
pp. 3451-3454 ◽  
Author(s):  
Jing Bo Zhang ◽  
Shu Fang Zhang ◽  
Qin Hu ◽  
Yi Jiang ◽  
Xiao Wen Sun
Keyword(s):  
Dynamic Performance ◽  
Phase Error ◽  
Noise Interference ◽  
Fast Tracking ◽  
Phase Jitter ◽  
Loop Design ◽  
Logical Control ◽  
Error Detector ◽  
High Dynamic ◽  
Fuzzy Logical

A differential phase error detector is inserted in the carrier loop structure for improving the dynamic performance of the loop in GNSS receiver in this paper. It is used to detect the abnormal phase jitter and amplify the adjusting increment for fast tracking. In order to avoid the differential detector amplifying noise interference in locking, fuzzy logical theory is introduced into the loop to control the amplification caused by the differential detector. Finally simulations show that the proposed design achieves high dynamic performance with effectively speeding up the tracking and widening the dynamic stress range.

scholarly journals Performance and Evaluation of GNSS Receiver Vector Tracking Loop Based on Adaptive Cascade Filter

2021 ◽  
Vol 13 (8) ◽  
pp. 1477
Author(s):  
Haotian Yang ◽  
Bin Zhou ◽  
Lixin Wang ◽  
Qi Wei ◽  
Feng Ji ◽  
...  
Keyword(s):  
Covariance Matrix ◽  
Traditional Method ◽  
Phase Error ◽  
Frequency Error ◽  
Tracking Loop ◽  
Loop Filter ◽  
Noise Covariance Matrix ◽  
Vector Tracking ◽  
Noise Covariance ◽  
Local Code

In the scenario of high dynamics and low C/N0, the discriminator output of a GNSS tracking loop is noisy and nonlinear. The traditional method uses a fixed-gain loop filter for error estimation, which is prone to lose lock and causes inaccurate navigation and positioning. This paper proposes a cascaded adaptive vector tracking method based on the KF+EKF architecture through the GNSS Software defined receiver in the signal tracking module and the navigation solution module. The linear relationships between the pseudo-range error and the code phase error, the pseudo-range rate error and the carrier frequency error are obtained as the measurement, and the navigation filter estimation is performed. The signal C/N0 ratio and innovation sequence are used to adjust the measurement noise covariance matrix and the process noise covariance matrix, respectively. Then, the estimated error value is used to correct the navigation parameters and fed back to the local code/carrier NCO. The field vehicle test results show that, in the case of sufficient satellite signals, the positioning error of the proposed method has a slight advantage compared with the traditional method. When there is signal occlusion or interference, the traditional method cannot achieve accurate positioning. However, the proposed method can maintain the same accuracy for the positioning results.

scholarly journals Design and Implementation of Vector Tracking Loop for High-Dynamic GNSS Receiver

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5629
Author(s):  
Rongjun Mu ◽  
Teng Long
Keyword(s):  
Real Time ◽  
Open Loop ◽  
Control Mode ◽  
Tracking Loop ◽  
Implementation Framework ◽  
Signal Tracking ◽  
Synchronization Problem ◽  
Vector Tracking ◽  
High Dynamic ◽  
Navigation Signals

For the tracking of high-dynamic satellite navigation signals, the conventional scalar tracking loop (STL) is vulnerable. Frequent signal-tracking interruption affects the continuity of navigation. The vector tracking loop (VTL) can overcome this disadvantage. However, there are some difficulties in implementing existing vector tracking methods on a real-time hardware receiver, such as the synchronization problem and computation load. This paper proposes an implementation framework of VTL based on a partial open-loop numerically controlled oscillator (NCO) control mode that can be implemented with minor modifications on an existing receiver platform. The structure of VTL, the design of the navigation filter, and the key points of hardware implementation are introduced in detail. Lastly, the VTL performance was verified by a GPS simulator test. The results show that the proposed VTL can run in real-time and be significantly improved in the tracking continuity of high-dynamic signals, tracking sensitivity, positioning accuracy, and recovery time for interrupted signals compared with those of STL.

scholarly journals High Dynamic Optimized Carrier Loop Improvement for Tracking Doppler Rates

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Amirhossein Fereidountabar ◽  
Gian Carlo Cardarilli ◽  
Marco Re
Keyword(s):  
Global Positioning System ◽  
Phase Error ◽  
Low Earth Orbit ◽  
Tracking Loop ◽  
Third Order ◽  
Satellite Systems ◽  
Dynamic Tracking ◽  
Global Positioning ◽  
Tracking Loops ◽  
High Dynamic

Mathematical analysis and optimization of a carrier tracking loop are presented. Due to fast changing of the carrier frequency in some satellite systems, such as Low Earth Orbit (LEO) or Global Positioning System (GPS), or some planes like Unmanned Aerial Vehicles (UAVs), high dynamic tracking loops play a very important role. In this paper an optimized tracking loop consisting of a third-order Phase Locked Loop (PLL) assisted by a second-order Frequency Locked Loop (FLL) for UAVs is proposed and discussed. Based on this structure an optimal loop has been designed. The main advantages of this approach are the reduction of the computation complexity and smaller phase error. The paper shows the simulation results, comparing them with a previous work.

Neural Network Assisted Vector Tracking Loop for Bridging GPS Signal Outages

2015 ◽  
Vol 764-765 ◽  
pp. 560-564
Author(s):  
Dah Jing Jwo ◽  
Zi Ming Wen
Keyword(s):  
Neural Network ◽  
Navigation System ◽  
Doppler Frequency ◽  
Numerical Control ◽  
Tracking Loop ◽  
The Neural Network ◽  
Solid Objects ◽  
Global Positioning ◽  
Vector Tracking ◽  
Improved Performance

Signal blockage and reflections from buildings and other large, solid objects can lead to accuracy degradation. One of the merits of the Global Positioning System (GPS) vector tracking loop (VTL) architectures is that the tracking loop can be assisted in such degraded signal environments. This paper proposes the incorporation of the neural network (NN) into the VTL for improving the positioning quality. The NN is used to bridge the GPS signal and prevent the error growth due to signal outage from spreading into the entire tracking loop. The NNs are employed for predicting adequate numerical control oscillator (NCO) inputs, i.e., providing better prediction of residuals for the Doppler frequency and code phase in order to maintain regular operation of the navigation system. The NN-assisted VTL demonstrates the capability to ensure proper functioning of navigation system. Results show that the NN-assisted VTL can effectively provide improved performance during degraded signal environments such as GPS outages.

scholarly journals Vector Tracking Algorithm Based on Adaptive Cubature Kalman Filter

2018 ◽  
Vol 36 (6) ◽  
pp. 1108-1115
Author(s):  
Xiaojun Zou ◽  
Baowang Lian ◽  
Zesheng Dan
Keyword(s):  
Kalman Filter ◽  
Carrier Frequency ◽  
Phase Error ◽  
Tracking Algorithm ◽  
Frequency Error ◽  
Test Results ◽  
Tracking Loop ◽  
Cubature Kalman Filter ◽  
Vector Tracking ◽  
Present Algorithm

In the vector tracking loop, there is a great error in the output of discriminator owing to the disturbance of noise. Cubature Kalman filter is proposed to replace the discriminator to process I/Q data and generate code phase error and the carrier frequency error in this paper. The present algorithm not only can avoid the nonlinear problem of discriminator, but also can reduce the bad effect of noise. Moreover, using cubature Kalman filter to deal with the nonlinear I/Q data is beneficial to preserve the accuracy of data processing. Because noise is unknown or time-varying, the filter should have the ability to respond to the changes of environmental noise. The innovation of measurements is used to estimate the covariance matrix of measurement noise in real time. Finally, a comparison is carried out between the present algorithm and the vector tracking algorithm based on discriminator. The test results show that the code phase error and the carrier frequency error are smaller, and the accuracy of navigation solution is also higher.

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