基于自适应均衡的超声波穿墙通信回波消除

Ultrasonic Through-Thick-Metal-Wall Communication with echo cancel ing Based on Adaptive Equalizer

超声波通信在船舶、大型密闭容器等电磁屏蔽环境中具有特别的优势。但超声波信道的多径效应导致的码间干扰限制了超声波通信速率,因此需要消除回波信号来降低系统的码间干扰。超声波信道通常是时变的,需要系统能够自适应地消除回波。文章利用基于LMS的自适应均衡器辨识出信道回波传递函数,并利用回波的软消除方法实现回波消除。采用Xilinx System Generator搭建系统模型,通过初始化指令自动生成250阶的横向滤波器结构。最后通过仿真验证了方法的可行性。

Ultrasonic communication system has special advantages over electromagnetic communication system in some spe- cific environment, such as vessel or closed container. But the multipath effect of the ultrasonic channel may cause the intersym- bol interference （ISI）. With the increase of the symbol rate, the ISI may lead to serious symbol error, which makes it impossible to increase the symbol rate without dealing with the echo problem. Since the ultrasonic channel could be time variant, it is necessary to introduce an adaptive filter to the ultrasonic communication system. This paper describes the structure of the LMS- based equalizer, which is used to identify the transfer function of echo and eliminate the echo with soft filtering. This system was designed with a 250-order adaptive equalizer by the initialization command in System Generator. Finally, the feasibility of this system was proved by simulation.