Design and FPGA Implementation of Quadrature Multiplexed BOC Signals

Abstract

Quadrature multiplexed BOC signal (QMBOC) is a modulation signal adopted by China BDS-3 system and it is a time domain implementation method of MBOC modulation. BDS-3 uses QMBOC modulation to achieve compatibility and interoperability with GPS and Galileo signals. This paper uses the time domain expression of QMBOC signal to generate QMBOC signal in real time based on FPGA. The generator mainly includes four modules: clock management module, code generation module, carrier generation module and subcarrier generation module. By adopting a unified system clock and precise phase control, the phase relationship between the real part and the imaginary part of the QMBOC signal is ensured, and the strict alignment among the subcarriers, the primary code, the secondary code and the carrier is achieved. The results show that the method for real-time generation of the QMBOC signal is relatively simple, occupies less resources, and is easy to implement in engineering. The real-time generation of the QMBOC signal not only provides a module design reference for the baseband signal processing of the receiving terminal, but also provides a test signal for the signal reception.