基于FFT的直扩系统中弱信号捕获方法

Acquisition based on FFT for weak signals in direct sequence spread-spectrum signals system

针对直扩系统中低信噪比环境下完成对伪码的捕获困难的问题,提出了利用多次相关累加提高接收机灵敏度的方法。并采用多段数据延时方法解决了相关累加过程中跨越数据跳变沿的问题。利用FFT和IFFT代替相关运算减少了运算量。并利用实时判决在高信噪比下省去不必要的操作减少了捕获时间。利用MATLAB仿真证明方法可行,既可在高信噪比下用较少资源完成捕获,又可在低信噪比下完成捕获。

Code acquisition in low SNR environment is a difficult problem in DSSS.Therefore,it is proposed to make use of coherent integration to improve the sensitivity of receiver.Using many parts of data which delayed a constant time between each other to solve the transition of data bits in coherent integration.And using FFT and IFFT operation to reduce the computational complexity.An adaptive decision method is introduced to leave out unnecessary operation and save acquisition time.The MATLAB simulation shows that this method is feasible.It not only can complete the acquisition at high SNR with less resources,but also can capture weak signals with favorable performance.