伽利略搜救系统多路信号融合及信噪比估计算法

Research on SNR Estimation and Fusion of Multi-channel Signals in Galileo SARSAT

伽利略搜救系统各通道代表不同的接收路径,同一时刻各通道输出的同源信号必须以合理的方式结合。根据多传感器融合原理,设计联合解调算法。首先计算各通道信号的信噪比,再利用信噪比信息实现各路信号的加权融合。对于信噪比估计,在高信噪比条件下采用判决反馈方法,而对于低信噪比条件则采用平方法,以适应系统信噪比动态范围大的特点。针对伽利略系统的特点,将判决反馈算法和平方算法推广应用到1.1弧度BPSK调制体系,并提出用三角函数计算正交支路功率的信噪比估计算法。仿真结果表明,信号融合和信噪比估计组合的联合解调算法能够有效地提高系统误码率性能。

Galileo SARSAT ground station might receive multiple replicas of a common beacon,and each is derived from the path dif- ferent from others.A joint demodulation algorithm is devised to combine these replicas in a proper way.Borrowing the thought of multi-sen- sor data fusion,the algorithm first computes the SNR of each replica,and then makes weighted combination according to SNR.As to SNR computation,the algorithm toggles between Decision Feedback Method and Square Method to accommodate the high dynamic SNR of the system.Both methods are extended to comply with the 1.1 BPSK scheme of Galileo system.A modification to the Square Method that cal- culates quadrature component power by exploiting its inherent rehtionship with in-phase component is also proposed.Simulation proves that the joint demodulation algorithm and associated SNR computation method can be used to promote the BER performance of the system.