scholarly journals Unambiguous Acquisition/Tracking Technique Based on Sub-Correlation Functions for GNSS Sine-BOC Signals

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 485 ◽  
Author(s):  
Fang Hao ◽  
Baoguo Yu ◽  
Xingli Gan ◽  
Ruicai Jia ◽  
Heng Zhang ◽  
...  
Keyword(s):  
Random Noise ◽  
Tracking Error ◽  
Satellite System ◽  
High Order ◽  
Signal Acquisition ◽  
Phase Detection ◽  
Binary Offset Carrier ◽  
Side Peak ◽  
Phase Discrimination ◽  
Coherent Integration

The autocorrelation function (ACF) of the Binary Offset Carrier modulation (BOC) signal for Global Navigation Satellite System (GNSS) has multiple peaks, ambiguity is easily generated during the synchronization of the baseband signal. Some methods have been proposed to remove the ambiguity, but the performance is not suitable for high-order BOC signals or does not maintain narrow correlation characteristics. This paper proposes a sub-function reconstruction synchronization algorithm to solve this problem, of which the key is to design a new local auxiliary code: the local Pseudo-Random Noise (PRN) code is divided into several new codes with different delays. The auxiliary code performs a coherent integration operation with the received signal. Then, a correlation function without any positive side peaks is obtained by multiplying the two correlation results to make the acquisition/tracking completely unambiguous. The paper gives a design scheme of navigation signal acquisition/tracking and deduces the theoretical analysis of detection performance. The phase discrimination function is provided. The performance of the method is analyzed from both theoretical and simulation aspects. Compared with the Binary phase shift keying-like (BPSK-LIKE) method, Subcarrier Phase Cancellation (SCPC) method and the Autocorrelation Side-Peak Cancellation Technique (ASPeCT) method, the proposed method has the best detection probability for the acquisition, which is 0.5 dB-Hz better than ASPeCT. For tracking, the proposed method performs best in terms of phase-detection curve, anti-multipath performance, and anti-noise performance. For high-order BOC signals, the SRSA technique successfully removes the false lock points, and there is only one multipath error envelope, and the code tracking error is almost the same as the ASPeCT method.

scholarly journals An Unambiguous Synchronization Scheme for GNSS BOC Signals Based on Reconstructed Correlation Function

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1982
Author(s):  
Xiyan Sun ◽  
Shaojie Song ◽  
Yuanfa Ji ◽  
Xingli Gan ◽  
Suqing Yan ◽  
...  
Keyword(s):  
Correlation Function ◽  
Detection Probability ◽  
Cross Correlation ◽  
Tracking Error ◽  
Modulation Method ◽  
Specific Method ◽  
Multipath Mitigation ◽  
Side Peak ◽  
Zero Crossing ◽  
Phase Discrimination

Binary offset carrier (BOC) modulation is a new modulation method that has been gradually applied to the Global Satellite Navigation System (GNSS) in recent years. However, due to the multi-peaks in its auto-correlation function (ACF), it will incur a false lock and generate synchronization ambiguous potentially. In this paper, an unambiguous synchronization method based on a reconstructed correlation function is proposed to solve the ambiguity problem. First, through the shape code vector constructed in this paper, the general cross-correlation function (CCF) expression of the BOC modulated signal will be obtained. Based on the features of the signal correlation function, it is decomposed into a matrix form of trigonometric functions. Then, it generates two local signal waves using a specific method, then the proposed method is implemented to obtain a no-side-peak correlation function by reconstructing the cross-correlation between the received signal and the two local signals. Simulations showed that it fully eliminates the side-peak threat and significantly removes the ambiguity during the synchronization of the BOC signals. This paper also gives the improved structure of acquisition and tracking. The detailed theoretical deduction of detection probability and code tracking error is demonstrated, and the corresponding phase discrimination function is given. In terms of de-blurring ability and detection probability performance, the proposed method outperformed other conventional approaches. The tracking performance was superior to the comparison methods and the phase discrimination curve only had a zero-crossing, which successfully removed the false lock points. In addition, in multipath mitigation, it outperformed the ACF of the BOC signal, and performs as well as the autocorrelation side-peak cancellation technique (ASPeCT) for BOC(kn,n) signals.

Generalised Theory on the Effects of Sampling Frequency on GNSS Code Tracking

2017 ◽  
Vol 71 (2) ◽  
pp. 257-280 ◽  
Author(s):  
Vinh T. Tran ◽  
Nagaraj C. Shivaramaiah ◽  
Thuan D. Nguyen ◽  
Joon W. Cheong ◽  
Eamonn P. Glennon ◽  
...  
Keyword(s):  
Tracking Error ◽  
Satellite System ◽  
Sampling Frequency ◽  
Code Rate ◽  
Integer Multiple ◽  
Delay Locked Loop ◽  
Coherent Integration ◽  
Baseband Signal Processing ◽  
Residual Code ◽  
Global Navigation Satellite

Synchronisation of the received Pseudorandom (PRN) code and its locally generated replica is fundamental when estimating user position in Global Navigation Satellite System (GNSS) receivers. It has been observed through experiments that user position accuracy decreases if sampling frequency is an integer multiple of the nominal code rate. This paper provides an accuracy analysis based on the number of samples and the residual code phase of each code chip. The outcomes reveal that the distribution of residual code phases in the code phase range [0, 1/ns), where ns is the number of samples per code chip, is the root cause of accuracy degradation, rather than the ratio between sampling frequency and nominal code rate. Doppler frequencies, coherent integration periods, front-end filter bandwidths and received Carrier to Noise ratios (C/N0) also influence receiver accuracy. Also provided are a sampling frequency selection guideline and new proposed estimates of the correlation output and the Delay Locked Loop (DLL) tracking error, which can be applied to precisely model GNSS receiver baseband signal processing.

Galileo E5 Signal Acquisition using Intermediate Coherent Integration Time

2019 ◽  
Vol 72 (3) ◽  
pp. 555-574
Author(s):  
Jérôme Leclère ◽  
René Landry
Keyword(s):  
Partial Correlation ◽  
Correlation Method ◽  
Satellite System ◽  
Integration Time ◽  
Signal Acquisition ◽  
Coherent Integration ◽  
L5 Signal ◽  
Galileo E5 ◽  
Low Sensitivity ◽  
Global Navigation Satellite

The acquisition of modern Global Navigation Satellite System (GNSS) signals may be difficult due to the presence of a secondary code. Indeed, short coherent integration times should be used without non-coherent integration, which implies a low sensitivity; or long coherent integration times should be used, requiring synchronisation with the secondary code and thus a full correlation, which implies a significant computational burden, especially for signals with long secondary codes such as the Galileo E5 signal. A third option that lies between the previous two is to perform a partial correlation using less than one secondary code period as input, however this is less efficient in terms of complexity than using an entire secondary code period, and the code's autocorrelation properties are completely changed. The authors recently proposed a method based on combining secondary code correlations, allowing the use of intermediate coherent integration times with the possibility to do non-coherent integrations, and the method was successfully applied to the Global Positioning System (GPS) L5 signal. This paper studies the application of the method to the Galileo E5 signal, compares it with the partial correlation method, and discusses the case where less than one secondary code period is used as an input

scholarly journals PERFORMANCE OF GNSS CARRIER-TRACKING LOOP BASED ON KALMAN FILTER IN A CHALLENGING ENVIRONMENT

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 1687-1693 ◽  
Author(s):  
Y. Luo ◽  
C. Yu ◽  
J. Li ◽  
N. El-Sheimy
Keyword(s):  
Kalman Filter ◽  
Model Simulation ◽  
Random Noise ◽  
Dynamic Environment ◽  
Satellite System ◽  
Phase Lock Loop ◽  
Integration Time ◽  
Loop Model ◽  
Tracking Loop ◽  
Coherent Integration

<p><strong>Abstract.</strong> The global navigation satellite system (GNSS) recently plays an extremely important role in positioning, navigation, and timing (PNT) applications for the modernized automations and mechanizations, e.g., unmanned aerial vehicles (UAVs), unmanned ground vehicles (UGVs), military aircrafts, etc. Nevertheless, GNSS signals are very vulnerable to the influence of various interferences when they are received on Earth, and the reason why it happens is that the long line-of-sight (LOS) distance between the satellite and the receiver user dramatically reduces the power strength after the signal reaches at the ground. The weak GNSS signal is hard to be handled with traditional phase lock loop (PLL), especially in a dynamic environment. Again, the trade-off among the coherent integration time of tracking loop, received signal power strength, and signal or user receiver dynamics is still a tough and remained problem to be solved. The Kalman filter (KF) is always a promising tool to efficiently decrease the random noise for the tracking process. In our work, we evaluate the performances of the tracking loop modelled with both standard KF and extended Kalman filter (EKF). An adaptive algorithm for the covariance matrix of the process noise is contained in our system to increase the tracking ability in a weak and dynamic environment. Besides, a noise channel is also contained to automatically adjust the priori measurement covariance for the KF tracking loop model. Simulation results demonstrate the performance with the proposed technique.</p>

A Main Peak Extraction Method for High-Order BOC Signals

2017 ◽  
Vol 70 (5) ◽  
pp. 1153-1169
Author(s):  
Fang Liu ◽  
Yongxin Feng
Keyword(s):  
Estimation Error ◽  
High Order ◽  
Global Navigation Satellite Systems ◽  
New Method ◽  
Main Peak ◽  
Phase Estimation ◽  
Binary Offset Carrier ◽  
Side Peak ◽  
Satellite Systems ◽  
Decision Efficiency

Binary Offset Carrier (BOC) modulation signals have been applied in Global Navigation Satellite Systems (GNSS) because they offer a higher positioning accuracy and higher multipath rejection. However, there is a drawback in that the autocorrelation functions have multiple side peaks, meaning that this technique also leads to the large main peak estimation error problem and a low correlation decision efficiency problem. In this paper, we propose a new Main Peak Extraction (MPE) method for high-order BOC signals to solve these problems. In the new method, the synthesis cross-correlation function is established, and the geometry graph is formatted to calculate the estimation main peak. We eliminate all side peaks and improve the main peak phase estimation precision under the condition that the sub-carrier phase is offset. The results of the simulation demonstrate that the new method can achieve better main peak decision efficiency, side peak cancellation ability and phase estimation performance than traditional methods.

An Improved Acquisition Method for High-Order BOC-Modulated Signals Based on Fractal Geometry

2013 ◽  
Vol 846-847 ◽  
pp. 1185-1188 ◽  
Author(s):  
Hua Bing Wu ◽  
Jun Liang Liu ◽  
Yuan Zhang ◽  
Yong Hui Hu
Keyword(s):  
Fractal Geometry ◽  
Output Signal ◽  
Signal To Noise Ratio ◽  
High Order ◽  
Main Peak ◽  
Signal To Noise ◽  
Binary Offset Carrier ◽  
Simulation Results ◽  
Modulated Signals ◽  
Acquisition Method

This paper proposes an improved acquisition method for high-order binary-offset-carrier (BOC) modulated signals based on fractal geometry. We introduced the principle of our acquisition method, and outlined its framework. We increase the main peak to side peaks ratio in the BOC autocorrelation function (ACF), with a simple fractal geometry transform. The proposed scheme is applicable to both generic high-order sine-and cosine-phased BOC-modulated signals. Simulation results show that the proposed method increases output signal to noise ratio (SNR).

scholarly journals Design of Unambiguous Combined Tracking Loop for GNSS Complex Subcarrier Signal

2018 ◽  
Vol 36 (1) ◽  
pp. 176-181
Author(s):  
Xianzhi Luo ◽  
Hongwei Zhao ◽  
Hao Yan
Keyword(s):  
Satellite System ◽  
Tracking Loop ◽  
Tracking Accuracy ◽  
Multiple Correlation ◽  
Data Simulation ◽  
Side Peak ◽  
Main Loop ◽  
Modulation Signal ◽  
Global Navigation Satellite ◽  
Complex Exponential

Complex subcarrier modulation signal, is a kind of BOC signal which is used complex exponential function as subcarrier, has been widely applied in GNSS(Global Navigation satellite system). The existence of multiple correlation peaks of the autocorrelation function of the complex subcarrier signal, will cause the acquisition error and tracking to the side peak when the signal is synchronized. To solve this problem, an unambiguous combined tracking loop for complex subcarrier signals is proposed. In this loop architecture, the main loop completes the coarse synchronization with BPSK-like algorithm, and the assisted loop realizes the accurate tracking together main loop. In this paper, the dual estimate tracking algorithm and the side-peak cancellation scheme are employed respectively in the assisted loop. The performance of tracking accuracy and anti-multipath capability of the proposed architecture is analyzed, and the practicability is verified by using the actual collected data. Simulation and experimental results show that the tracking structure proposed in this paper is practical and has good performance of anti-noise and anti-multipath.

scholarly journals Self-Assisted First-Fix Method for A-BDS Receivers with Medium- and Long-Term Ephemeris Extension

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Zilong Shen ◽  
Jing Peng ◽  
Wenxiang Liu ◽  
Feixue Wang ◽  
Shibing Zhu ◽  
...  
Keyword(s):  
Dynamic Models ◽  
Rapid Development ◽  
Real Data ◽  
Satellite System ◽  
Time Interval ◽  
Signal Acquisition ◽  
Positioning Accuracy ◽  
Broadcast Ephemeris ◽  
Intelligent Logistics

As a sensor for standalone position and velocity determination, the BeiDou Navigation Satellite System (BDS) receiver is becoming an important part of the intelligent logistics systems under rapid development in China. The applications in the mass market urgently require the BDS receivers to improve the performance of such functions, that is, shorter Time to First Fix (TTFF) and faster navigation signal acquisition speed with Ephemeris Extension (EE) in standalone mode. As a practical way to improve such functions of the Assisted BDS (A-BDS) receivers without the need for specialized hardware support, a Self-Assisted First-Fix (SAFF) method with medium- and long-term EE is proposed in this paper. In this SAFF method, the dynamic Medium- and Long-Term Orbit Prediction (MLTOP) method, which uses the historical broadcast ephemeris data with the optimal configuration of the dynamic models and orbit fitting time interval, is utilized to generate the extended ephemeris. To demonstrate the performance of the MLTOP method used in the SAFF method, a suit of tests, which were based on the real data of broadcast ephemeris and precise ephemeris, were carried out. In terms of the positioning accuracy, the overall performance of the SAFF method is illustrated. Based on the characteristics of the medium- and long-term EE, the simulation tests for the SAFF method were conducted. Results show that, for the SAFF method with medium- and long-term EE of the BeiDou MEO/IGSO satellites, the horizontal positioning accuracy is about 12 meters, and the overall positioning accuracy is about 25 meters. The results also indicate that, for the BeiDou satellites with different orbit types, the optimal configurations of the MLTOP method are different.

Output tracking control of high-order nonlinear systems with dynamic uncertainties

2019 ◽  
Vol 42 (8) ◽  
pp. 1511-1520
Author(s):  
Zong-Yao Sun ◽  
Yu-Jie Gu ◽  
Qinghua Meng ◽  
Wei Sun ◽  
Zhen-Guo Liu
Keyword(s):  
Nonlinear Systems ◽  
Tracking Control ◽  
Tracking Error ◽  
High Order ◽  
Approximation Technique ◽  
Zero Dynamic ◽  
Adding A Power Integrator ◽  
Output Tracking ◽  
Output Tracking Control ◽  
Dynamic Uncertainties

This paper investigates the output tracking control problem for a class of nonlinear systems with zero dynamic. On the basis of adding a power integrator method and approximation technique, an appropriate controller is proposed to guarantee that the tracking error turns to a preassigned neighborhood of the origin. The systems under investigation allow unmeasurable dynamic uncertainties, unknown nonlinear functions and unknown high-order terms. As an application, two examples are provided to illustrate the effectiveness of a control strategy.

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