Adaptive Digital Signal Processing and Its Application to Comnmunication Systems

1.复自适应IIR陷波滤波器的稳态分析本文提出了一种新的复数自适应无限冲激响应(IIR)陷波滤波器结构，可用于通信和雷达系统中的复正弦波检测。提出的结构是基于梯度算法的。对稳态系数的波动进行了定量分析。结果表明，方差复系数的波动不依赖于输入正弦波的角频率。计算机模拟的结果也证实了理论预测。基于IIR陷波的自适应窄带干扰抑制提出了一种基于格型自适应IIR陷波的简化自适应算法来改善直接序列扩频通信系统的性能。这种改进是通过抑制接收的直接序列扩频二进制相移键控(BPSK)信号中的窄带干扰来实现的。除了与输入加性高斯白噪声有关的噪声外，还分析了稳态变系数波动引起的泄漏正弦噪声。利用陷波和伪噪声(PN)相关器输出的统计特性，证明了使用干扰抑制滤波器可以改善直接序列扩频系统的性能。计算机模拟结果用于确认解析推导的表达式。

1. Steady-State Analysis of Complex Adaptive IIR Notch FiltersWe present a new structure for complex adaptive infinite impulse response (IIR) notch filter which is useful for the detection of a complex sinusoid in communication and rader systems. The proposed structure is based on gradient algorithm. A quantitative analysis for the steady-state coefficient fluctuation has been obtained. It has been shown that the variance complex coefficient fluctuation does not depend on the angular frequency of the input sinusoid. The results of computer simulations are also shown which confirm the theoretical prediction.2. Adaptive Narrow-Band Interference Suppression Using IIR Notch FilterImprovement of direct sequence spread spectrum (DSSS) communication systems' performance using a lattice based adaptive IIR notch filter with a simplified adaptation algorithm is presented. The improvement is shown to be achieved by rejection of a narrowband interference in a received DSSS binary phase shift keying (BPSK) signal. Apart from noise associated with input additive white gaussian noise, noise attributed to leakage sinusoids due to fluctuation of steady-state variable coefficients is also analysed. Using statistical properties of notch filter and pseudonoise (PN) correlator outputs, improvement of the performance of a DSSS systems gained by the use of interference rejection filter is shown. Computer simulation results are used to confirm analytically derived expressions.