采用块更新和NLMS算法的线性回波消除器实现

摘要

This article describes the way to realise line echo canceller (LEC) on TMS320C54X series of 16-bit fixed-point digital signal processors. Two different specific implementations for adaptive transversal echo canceller filter are discussed in detail; the block update and the Normalized Least Mean Square ( NLMS, or stochastic gradient). The cycle counts for kernel code and the valuation of memory requirements in regard to two implementation ways of LEC are presented, the error outputs of LEC in regard to two algorithms of the number of tap and the iteration step size are tested and recorded. Based on the features of the TMS320C54X DSP, the hardware and software of the chips are used fully and efficiently in implementations. It proves that the scheme is easy to realise and control, and the performance and the reliability are all greatly enhanced. The ultimate choice of two different algorithms should be made after being tested in practical telephone network environment and according to industry standards.%描述采用16位定点DSP处理器TMS320C54X系列实现线性回波消除器的方法.详细讨论两种不同的自适应横向回波消除滤波器的具体实现,即块更新和归一化最小均方法NLMS(随机梯度法).给出LEC两种实现方式内核代码周期数及内存要求的估值,测试并记录LEC两种算法基于抽头数和迭代步长的误差输出.结合DSP芯片的特征,该方法充分有效地利用了其软硬件资源.经验证,该方案易于实现和控制,性能以及可靠性均得到大幅增强.对于两种算法的选择,应在实际的电话网络环境中,根据工业标准测试作最终判断.