부상관함수 결합에 기반한 Cosine 위상 BOC 코드 추적 기법

Binary offset carrier (BOC) signal synchronization is based on the correlation between the received and locally generated BOC signals. Thus, the multiple side-peaks in BOC autocorrelation are one of the main error sources in synchronizing BOC signals. Recently, a new correlation function with no side-peaks was proposed for sine or cosine phased BOC signal synchronization by the authors [7]. In this paper, we propose a novel correlation function for composite binary offset carrier (CBOC) signals by using the similar method to that in [7], which has a better power ratio than the CBOC autocorrelation.

The recent researches on the tracking of binary offset carrier (BOC) modulated signals have been studied focusing onresolving the ambiguity problem caused by the multiple side-peaks in BOC autocorrelation. In this paper, we proposea novel unambiguous BOC tracking scheme with an improved tracking performance by using partial-pulses of BOCsignals. Firstly, we observe that a sub-carrier consists of two partial rectangular pulses referred to as partial-pulses,and then, generate multiple partial-correlations composing the BOC autocorrelation. Finally, a correlation function withno side-peak is constructed by combining the partial-correlations, and then, a delay lock loop employing the proposedunambiguous correlation function adjusts the phase of the local BOC signals. From numerical results, it is confirmedthat the proposed scheme provides a better tracking performance than the conventional schemes in terms of thetracking error standard deviation.

With the rapid development of Global Navigation Satellite Systems (GNSS). The binary offset carrier (BOC) signal was proposed to separate new navigation signal from traditional BPSK in frequency and it has better accuracy and anti-multipath performance compared with the BPSK of the same code rate. But the ambiguity caused by the multi-peaks of auto-correlation function makes traditional acquisition technique not applicable to BOC.A novel unambiguous acquisition algorithm for sine BOC signals is proposed in this paper. There are two types of local reference signals: the BOC signal and a designed binary auxiliary signal. They are both correlated with the received signals. Then, a correlation function unambiguous for acquisition of BOC signal is obtained by multiplying the two correlation results. In the acquisition stage of BOC(10,5), the detection probability of the proposed method is approximately 1.5 dB better than that of GRASS and 2 dB better than that of SPAR. For BOC(14,2), the detection probability advantages of the proposed method increase to 6 dB and 7.5 dB . In conclusion, the proposed method can eliminate ambiguity and has significant performance advantages compared with the above methods.

It is well known that code and carrier-phase multipath, which has been under study for over two decades, is the limiting error sources in high-precision differential GPS applications. In virtually every study, however, the effects of autocorrelation function are considered little. This article focuses on the bounds of code and carrier-phase multipath error in terms of GNSS (Global Navigation Satellite Systems) signals autocorrelation functions, which result from a fundamental theoretical description and mathematical modeling of GNSS receiver. Firstly, an overview of the characteristics of the BOC (Binary Offset Carrier) signal ACF (autocorrelation function) is given in the paper. The impact on the DLL (delay-lock loop) and PLL (phase lock loop) discriminator functions are derived in the followed section and consequently a general description of multipath errors are obtained for the BOC signals. This quantifies the influence of limited bandwidth on receiver tracking error due to multipath. Finally, the simulation results show a distinct change in the error envelope for BOC signals from which has been got using current GPS C/A code signal.

The optimized design of the spreading modulation technique is considered to be the major way to achieve both spectrum compatibility and performance improvement. To allow a variety of signals to share the limited frequency band of GNSS and further improve the signals’ ranging accuracy and anti-interference performance, several new spreading modulation techniques have been proposed in recent years. In this chapter, we will introduce a variety of typical spreading modulation techniques such as BPSK with rectangular chips (BPSK-R), binary offset carrier (BOC), binary coded symbol (BCS), composite BCS (CBCS), time-multiplexed BOC (TMBOC), composite BOC (CBOC), quadrature multiplexed BOC (QMBOC), as well as alternative BOC (AltBOC). The processing ambiguity threat of BOC and MBOC signals and possible solutions are also discussed. Considering that in the next-generation GNSS implementations, new requirements and new constraints will constantly emerge and new modulation methods will be needed, this chapter is not meant to be regarded as a review of the development of navigation signal modulation technology, or an interpretation of the signal formats being used by several major satellite navigation systems. Instead, we regard the spreading modulations used in satellite navigation signals as general techniques and focus our discussion on the principles of these modulation techniques and the design ideas behind their generation processes.

Several new global navigation satellite system modulations adopt a binary offset carrier (BOC) subcarrier to shape the signal spectrum, increase the frequency separation and improve the tracking performance. BOC modulated signals are, however, characterised by ambiguous multi‐peaked correlation functions and several techniques have been proposed in the literature to solve the problem of locking into secondary peaks. In this study, a novel unambiguous BOC tracking technique, the double phase estimator (DPE), is designed to account for the effect of signal bandlimiting. The DPE is an effective alternative to the double estimator (DE) tracking technique where the subcarrier lock loop is replaced by a subcarrier phase lock loop. In the presence of signal bandlimiting, the DPE is able to generate local signal replicas matched in a better manner to the input components, outperforming the DE. The performance of the DPE is thoroughly characterised and the processing of real wideband BOC signals is used to demonstrate the effectiveness of the algorithm proposed. In addition to this, the DPE requires a lower computational load than the DE and thus should be adopted for the processing of wideband BOC signals.

The global navigation satellite system (GNSS) signal modulation type plays a crucial role in determining the performances of positioning, navigation and timing (PNT) services. Currently, the binary offset carrier (BOC) modulation signal and binary coded symbol (BCS) modulation signal are both bipolar signals, which greatly restrict the room of improving the GNSS signal performance. Therefore, multi-level coded symbol (MCS) modulation has received great attention in the field of GNSS signal design. The MCS modulation is the most extensive step-coded symbol modulation mode, where BOC modulation and BCS modulation are its special cases. Since the waveform symbol of the MCS modulation signal can be arbitrarily valued, the optimal GNSS signal can be designed. However, like the BOC modulation signal, the MCS modulation signal also has the problem of ambiguous tracking, and then results in a large pseudo range measurement error, which is unacceptable for the new generation GNSS with high accuracy. In recent years, the unambiguous tracking of GNSS signals has become a hot research subject in the navigation signal processing domain and many methods are presented, and those methods can be divided into three categories:BPSK-like method, bump jump (BJ) method, and side-peak cancellation (SC) method. However, these methods are designed for BOC signal, and they are not suitable for MCS signal. Therefore, in this paper we propose a general unambiguous tracking algorithm based on the pseudo correlation function (PCF), which is suitable for MCS modulated signals. Firstly, the unitary expression of MCS modulated signal based on waveform value vector is given, then the unitary formula of cross-correlation function for MCS signal is derived and the definition of PCF is given. Then the constraint condition which should be satisfied to realize unambiguous tracking is analyzed in depth, and the universal constructing method of two reference signals and the relationship between each other are derived according to this constraint condition, which brings great convenience for solving the specific MCS signal. The code tracking loop model of GNSS receiver based on the proposed method is illustrated. It is observed that the proposed method can receive different MCS signals under the same receiver loop framework, and can simplify the design of the receiver while eliminating the tracking ambiguous problem. Finally, as a special case of MCS signal, the applications of the proposed method in four kinds of BOC signals are discussed respectively, and then the waveform value vector of the reference signal and the unitary expression of code discriminator are derived. Simulation results show that the proposed method can effectively solve the ambiguous tracking problem of MCS signal, which has good performance and broad application prospect.

The long spreading code and the binary offset carrier (BOC) modulation technique are used in the next-generation Global Navigation Satellite System (GNSS) to improve positioning performance and to reduce inter-GNSS interference; however, the signal acquisition process of a GNSS receiver can take more time and requires additional hardware resources than legacy Global Positioning System (GPS) receivers. This paper presents the BOC 2-D compressed correlator (TDCC) technique for the fast acquisition of the next-generation GNSS signals. In the proposed BOC-TDCC, signal power in neighboring code-phase hypotheses and Doppler frequency hypotheses can be coherently combined and tested by a single compressed correlator in the first stage, and the conventional correlator-based serial search technique is employed in the second stage to test each hypothesis combined in the first stage. The performance of the BOC-TDCC is demonstrated with numerous Monte Carlo simulations and tested with real data. The BOC-TDCC has much lower mean acquisition time (MAT) than other conventional search schemes, which demonstrates that the BOC-TDCC is an effective search scheme for next-generation GNSS signals.

Multipath is a dominant source of positioning errors in global navigation satellite system receivers. It is difficult to design multipath mitigation techniques for binary offset carrier (BOC) signals due to the complicated autocorrelation function of BOC signals and localized variations of multipath. In this paper, a dual high resolution correlators (DHRC) technique is proposed for BOC signals to mitigate code and subcarrier multipath errors, as well as the carrier multipath error that is neglected by common techniques. Based on the concept of dual binary phase-shift keying (BPSK) tracking, the BOC signal is decomposed into two BPSK signals located in the upper and lower sidebands, respectively, thereby transforming the multipath mitigation in the BOC signal into the multipath mitigation in the upper and lower sidebands. Two narrow correlation functions of the upper and lower sidebands are synthesized using multiple correlation values, so the multipath outside the main peak of the synthesized correlation function is eliminated. The peak value of the synthesized correlation function is reduced from the original ACF, resulting in a large noise error. Therefore, a complementary filter is designed to compensate the noise error. Theoretical analysis and simulation results demonstrate that the DHRC technique with complementary filters can significantly mitigate multipath errors for BOC signals with slight thermal noise performance loss.

SummaryIn this paper, we propose an efficient method for eliminating ambiguity in the acquisition and tracking processes of binary offset carrier (BOC)‐modulated signals. Our contribution is realized in two stages. The first one is based on the use, at the receiver end, of optimized locally generated subcarrier sequences to get a completely unambiguous composite correlation function (CF). This first stage is used to initialize and control the second stage of the proposed method designed on the basis of a maximum likelihood algorithm (MLA) to mitigate, specifically, multipath (MP) effect. In fact, the idea is to combine, in this second stage, the received signal (affected by noise and MP) with a set of locally generated ideal BOC(m,n)‐modulated signals, which are delayed and weighted by the MLA‐estimated parameters of delays, amplitudes, and phases of all the MP signals, to obtain an unambiguous CF with better performance. The simulation results, based on MATLAB tool, have demonstrated that the proposed method effectively eliminates the ambiguity problem. Besides, a comparative study with several methods has shown that the proposed method grants better performance than the most popular techniques.

With the development of satellite navigation technology, BOC (Binary Offset Carrier) signals are proposed and applied in navigation system. However, in the advantages of enhancing the utilized rating of the band resource, some new problems are also emerging in the acquisition processing. On the basis of analyzing the limitations of the existing methods in suppressing side peaks, a NCCFR (New Cross-Correlation Function Reconstruction) algorithm is proposed, in which different modulation coefficients are used to construct correlation function with a shifter phase. The simulation results show that the new algorithm can suppress first side peaks and restrain other side peaks.

The tracking accuracy of baseband Delay Locked Loop (DLL) with narrow loop band is studied. The equivalent phase discrimination model of code delay correlator is provided, and the correlation functions and power spectrum density functions of correlator output port noise and its equivalent noise at the input port are developed, then the simplified calculation equation of the tracking accuracy of linear DLL with narrow loop band is deduced.

The authors present a nonconventional joint data demodulation-pseudo-noise (PN) code tracking scheme for direct sequence (DS) spread-spectrum (SS) signals which solves problems of component imbalance and sensitivity with hardware simplicity and no performance degradation. An integrate-and-dump Costas loop is used for carrier recovery and data demodulation of the SS signal. Both data and carrier are then used to derive the baseband error signal of the code tracking loop. Moreover, a single passband correlator is used to perform the early-late correlation, leading to a hardware complexity equivalent to that of the tau-dither scheme, but without its loss in performance. Results of a thorough theoretical analysis of the system in an additive Gaussian noise (AWGN) environment are reported. They provide performance curves in terms of steady-state jitter and mean time to first lock loss. A superior jitter performance for low values of E/sub b//N/sub 0/ with respect to a traditional noncoherent delay lock loop (DLL) is shown, along with the potential gain of Manchester coding upon the more usual NRZ format.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Navigation signals are the basis of satellite navigation systems, which determine the navigation systems' performance (such as tracking accuracy, anti-interference capability etc.), and are determined by some constraints (such as radio frequency resources, construction cost, technology level etc.). The aim of signal design is to select "proper" signals considering these above factors and make tradeoffs between performance and constraints. This paper will summarize the signal structure evolution of present satellite navigation and conclude some principles and issues which will be greatly valuable to our 2nd satellite navigation system. There's four main satellite positioning systems presently, the U.S. Global Positioning System (GPS), the Russian Global Navigation Satellite System (GLONASS), the Europe Galileo satellite navigation system and the Chinese BD-1 satellite positioning system. Among these systems, the signal characteristics of GPS and Galileo are good reference to our 2nd satellite navigation system. The improvement of GPS signals is a main aspect of GPS modernization. The aim of GPS modernization is mainly to modernize its signal structure so as to improve the whole systems' performance. The signal structure of Galileo has been revised for several times, and its present signal is the results of long time signal design. From GPS modernization and Galileo signals status, we can summarize some key specifications of navigation signals and some technologies to support these specifications. Based on this, we'll discuss some problems which should be attentive in our country's 2nd satellite navigation system and give some suggestions. This paper is organized into five sections. The first section will give a brief introduction of present satellite navigation system and their main features. Section two will review the GPS and Galileo signals structure evolution, including GPS modernization, Galileo signals status and the comparison of two systems' signals. In the third section, the relationship between signal parameters and system performance will be analyzed, including RF signal characteristics, modulation type, ranging code (such as code type, length and rate) and navigation data. In section four we will discuss some inspiration and technologies concerning our 2nd satellite navigation system, such as the use of multiple frequency signals (ionospheric delay estimation and carrier ambiguity resolution), pilot tones & dataless channel, binary offset carrier (BOC) modulation, and so on. The last section is conclusion, in which the whole paper will be retrospected and some useful conclusion will be given.

To address the issue of reduced motion accuracy in tracked sandblasting robots caused by nonlinear slippage on steel grit-covered hard surfaces, a hierarchical control framework combining model and data learning is proposed to enhance dual-motor coordination precision and terrain disturbance suppression capability. The inner layer employs a slip-mode control-cross-coupling (SMC-CCC) algorithm, combined with a novel composite approach law, to simultaneously optimize motor tracking error and synchronization error. The outer layer employs a coupled simulation of multi-body dynamics and discrete element method (MBD-DEM) to generate high-fidelity data, which trains a radial basis function neural network (RBFNN) to predict and compensate in real time for slip disturbances caused by track-ground interactions. The standard deviation of dual permanent magnet synchronous motor synchronous error decreased to 1.12, while the standard deviation of tracking error dropped to 7.86. After RBFNN compensation, vehicle lateral deviation was reduced to 70.08 mm—a 92.28% decrease compared to the uncontrolled condition—with slip rate stabilizing between 20% and 25%. In summary, the proposed hierarchical framework effectively addresses motion instability issues beneath steel grit surfaces: SMC-CCC ensures motor coordination precision, while RBFNN achieves adaptive compensation for nonlinear slippage based on MBD-DEM data, providing a viable solution for high-precision motion control in complex terrain.