Multipath is one of the dominant error sources of code tracking in indoor, urban district and other harsh environments. In order to eliminate multipath interference, a BAP-UKF method is introduced to estimate the multipath parameters of the weak GPS signal. For suppressing noise, interference and improving the signal to noise ratio, this method uses an block-averaging signal pre-processing method to process the received weak GPS signal. The signal after pre-processed through the multipath correlators. The in-phase or quadrature phase values are used as the observational measurements of unscented Kalman filter to estimate the code tracking＇s multipath parameters such as amplitude ,code delay,phase,carrier Doppler. The simulation results show that this method can effectively estimate multipath parameters of weak GPS signal,which carry noise ratio is down to 21 dB-Hz,so it proves the effectiveness of this method.%在室内、城市中心等恶劣环境下,多径效应已成为码跟踪的主要误差源.采用一种数据块平均预处理一无迹卡尔曼滤波器(BAP-UKF)方法来估计微弱GPS信号的多径参数,该方法采用数据BAP方法处理接收到的微弱GPS信号,以抑制噪声和干扰,提高接收信号的信噪比;经过BAP的信号通过多径相关器后的同相或正交相值,将作为UKF的观测量来估计码跟踪时的多路径的幅值、码延时、相位、载波多普勒等参数.仿真结果表明:该方法能够有效地估计出载噪比低至21dB-Hz的微弱信号多径参数,从而证明了其有效性.
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