直序扩频系统中频信号的同时解扩解调方法

常规直序扩频接收机将中频信号的解扩、解调分立进行,获得的处理增益为扩频码的周期。对于输入信噪比极低的系统,该处理增益难以满足系统低误码率的要求。在基于软件无线电的直序扩频系统中,接收机可以对中频采样信号同时进行解扩解调,分析表明,当采样率满足一定条件时,能够获得比常规方法更高的处理增益,适宜在低信噪比系统中应用。

Simultaneous Despread and Demodulating Method of IF Signal in DSSS System

The normal receivers of DSSS system despread and demodulate the IF signal separately, their process-gains are the period of the pseudo-noise sequence. But these process-gains usually cannot satisfy a low bit-error-rate if the signal-noise-ratio of input signal is very low. In a DSSS system based on the software radio, the receiver can despread and demodulate the IF signal simultaneously. It can be proved that this method can get a higher process-gain when the sample rate meets a certain condition, so it can be used in a low signal-noise-ratio system.