Study And SDR Implementation Of Digtal Base-Band Speech Enhancement Algorithm

In the wireless communication system,the speech signal is corrupted acoustically by noise between the way from transmitter to receiver.As a result, the quality of speech signal is degraded more or less.in severe cases,we can't communicate completely.Numerous methods are designed to solve this problem.for example,speech enhancement algorithms is an effective one.Noise changes in different situations,so we can't find a versatile speech enhancement algorithms that work effectively in all practical enviroment.This thesis is based on software defined radio(SDR) hardware platform which applied in shortwave serial wireless communication system. So We focus on finding a method to enhance speech corrupted by broadband noise which is a very common noise in this communication system.This thesis includes two parts:1.Theory research and simulation works about speech enhancement algorithms.2.Construction of speech enhancement system based on the SDR hardware platform.Following is the main work:In the first part, we introduce some basic principles,then study the noise estimation algorithm based on minimum tracking method which was designed by R.martin and improved lately himself.finally,we give a speech enhancement algorithm combining spectral subtraction and perceptual auditory masking effect.Simulation result shows that this algorithm provides good performance.The second part discusses the establishment of the SDR hardware platform and implementation of the speech enhancement system. At last,we do some optimization works for this real-time system.