Composite Binary Offset Carrier Signals Research Articles

SSCM: An Unambiguous Acquisition Algorithm for CBOC Modulated Signal

Composite binary offset carrier (CBOC) signal has been widely researched in GNSS. The main ingredient of CBOC signal is BOC(1,1) signal. Usually, the acquisition method for BOC(1,1) signal is used to capture CBOC signal, while the research of special acquisition method for CBOC signal is rare. In this letter, according to the principle and characteristics of CBOC signal, a special side-peak cancellation method (SSCM) is proposed and simulated. In this method, two special auxiliary signals are introduced. And the local reference signals are obtained by multiplying the data channel signal and pilot channel signal by the auxiliary signals. The cross-correlation results from the received pilot signal and the two local pilot signals with different auxiliary signals will subtract from one another. Then, side peaks of correlation function and in-band noise of pilot channel are suppressed, while the data channel has the same operation results. At last the outputs of pilot channel and data channel will be added up to make full use of the received signal power. By this way, the acquisition efficiency, accuracy, and adaptability to low signal-to-noise ratio (SNR) conditions for CBOC signal have been improved, alongside possible solution when the GNSS receiver works in a critical environment.

A novel unambiguous composite binary offset carrier(6,1,1/11) tracking based on partial correlations

This paper proposes a novel unambiguous correlation function for composite binary offset carrier (CBOC) signal tracking based on partial correlations. In the proposed scheme, first, we partition sub-carriers of the CBOC signal into partial sub-carriers, and subsequently, we obtain partial correlations by correlating the partial sub-carriers with the received CBOC signal. Finally, a novel unambiguous correlation function with no side-peak is constructed by combining the partial correlations in a specially designed way. Unlike the conventional schemes, the proposed scheme does not require any auxiliary signal and from numerical results, it is found to offer a better tracking performance than those of the conventional schemes in terms of the tracking error standard deviation (TESD) and multipath error envelope (MEE).

Pseudo-Correlation-Function Based Unambiguous Tracking Technique for CBOC (6,1,1/11) Signals

Binary Offset Carrier (BOC) signal planned for future Global Navigation Satellite System (GNSS) provided better positioning accuracy and smaller multipath error than GPS C/A signal. However, due to the multiple side peaks in the auto-correlation function (ACF) of the BOC modulated signals, a receiver may false lock onto one of the side peaks in the tracking mode. This false lock would then result in a fatal tracking error. In this paper, we propose an unambiguous tracking method for composite BOC (CBOC) signals to mitigate this problem. It aims to reduce the side peaks of the ACF of CBOC modulated signals. It is based on the combination of traditional CBOC correlation function (CF) and reference CF of unmodulated pseudo- random noise code (PRN code). First, we present that cross-correlation function (CCF) with unmodulated PRN code is close to the secondary peaks of the traditional CBOC. Then, we obtain an unambiguous correlation function by subtracting traditional CBOC ACF from these CFs. Finally, the tracking performance for the CBOC signals is examined, and it is shown that the proposed method has better performance than the traditional unambiguous tracking method in additive white Gaussian noise (AWGN) channel.

합성 이진 옵셋 반송파 신호 추적을 위한 새로운 비모호 상관함수

In this paper, we propose a novel unambiguous correlation function for composite binary offset carrier (CBOC) signal tracking. First, we observe that a sub-carrier of CBOC signal is seen as a sum of four partial sub-carriers, and generate four partial-correlations composing the CBOC autocorrelation. Then, we obtain an unambiguous correlation function with a sharp main-peak by re-combining the partial correlations. From numerical results, we confirm that the proposed unambiguous correlation function offers a better tracking performance than the conventional correlation functions in terms of the tracking error standard deviation and multipath error envelope.

Two-Step Galileo E1 CBOC Tracking Algorithm: When Reliability and Robustness Are Keys!

The majority of 3G mobile phones have an integrated GPS chip enabling them to calculate a navigation solution. But to deliver continuous and accurate location information, the satellite tracking process has to be stable and reliable. This is still challenging, for example, in heavy multipath and non-line of sight (NLOS) environments. New families of Galileo and GPS navigation signals, such as Alternate Binary Offset Carrier (AltBOC), Composite Binary Offset Carrier (CBOC), and Time-Multiplex Binary Offset Carrier (TMBOC), will bring potential improvements in the pseudorange calculation, including more signal power, better multipath mitigation capabilities, and overall more robust navigation. However, GNSS signal tracking strategies have to be more advanced in order to profit from the enhanced properties of the new signals.In this paper, a tracking algorithm designed for Galileo E1 CBOC signal that consists of two steps, coarse and fine, with different tracking parameters in each step, is presented and analyzed with respect to tracking accuracy, sensitivity and robustness. The aim of this paper is therefore to provide a full theoretical analysis of the proposed two-step tracking algorithm for Galileo E1 CBOC signals, as well as to confirm the results through simulations as well as using real Galileo satellite data.

Research and implementation of tracking algorithm for CBOC modulation navigation signal

With 4-level Sub-carrier, the Composite Binary Offset Carrier (CBOC) signal increases significantly difficulty of processing baseband code in navigation receiver. This paper analyzes the tracking performance of CBOC(6,1,1/11) signal, and improves the TM61 tracking algorithm according to the characteristic of sub-carrier. This method adopts BOC(1,1) to synchronize the signal at the initial stage of tracking, and uses BOC(6,1) to enhance the accuracy of tracking after achieving stable synchronization. Finally, the proposed method is validated by independently developed platform hardware. The results show that under the premise of ensuring accuracy of tracking, the proposed method effectively solves the problem of false locked caused by multiple peaks of BOC(6,1) autocorrelation function, and reduce the request of accuracy of acquisition.