A MBOC Signal Tracking Algorithm based on Split Processing Technique

Abstract

Multiplexed binary offset carrier (MBOC) spreading modulation will be widely applied in the next generation Global Navigation Satellite System (GNSS). The MBOC(6,1,1/11) power spectral density is a mixture of BOC(1,1) spectrum and BOC(6,1) spectrum, which has no restrictions on the time waveforms to produce the spectrum, allowing flexibility in implementation. For example, the time-multiplexed BOC (TMBOC) is used by GPS L1C, the composite BOC (CBOC) is used by Galileo E1 OS and the quadrature multiplexed BOC (QMBOC) is used by BDS B1C. The BOC(6,1) component is selected for the MBOC signals in order to narrow the auto-correlation peak, thereby improving the code tracking accuracy and anti-multipath performance. As in traditional MBOC tracking method, the BOC(1,1) component and the BOC(6,1) component are processed at the same time and then a composite autocorrelation function is generated, which has some flat or reversed slope near the main peak. Moreover, the method does not take full advantage of the BOC(6,1) performance as the ranging accuracy can be improved further. This paper investigated a tracking algorithm for MBOC signals based on split processing of the BOC(1,1) and BOC(6,1) components, which had been inspired by GPS L2P semi-codeless tracking technique. As in the proposed method, the BOC(1,1) and BOC(6,1) components are considered as two independent signals who share a common carrier. The receiver acquires the BOC(1,1) component and tracks it with a short integration time to adapt to dynamic environments. A longer integration time is then used for tracking the BOC(6,1) component to obtain a higher signal to noise and a better ranging accuracy. For sake of better utilizing the BOC(6,1) component, a closed loop architecture and an open loop architecture are proposed and investigated in the paper. As the two components are processed separately, the ranging potential of MBOC signals is going to be further developed without comprising the dynamic performance.