By complementing the proposed scheme with methods to estimate the fractional code delay , the acquisition unit an provide high quality delay estimates such that it can instead of the delay locked loop in the traditional ds receiver . after dispreading successfully , this dissertation introduces a method to estimate the doppler - shift directly from some samples based maximum likelihood estimation , and then revise it forwardly 在成功解扩之后,本文利用最大似然估计从l个样点中直接估计出残余多普勒频偏,并进行前向频偏校正,来代替传统扩频接收机中的科斯塔斯环,经仿真证明该方法的估计精度完全满足解调的要求。
Most of the lectures on nbi suppression assume that the spread spectrum signal and the background noise are white . this assumption cannot stand up in digitalized receiver because of the if oversampling and digital low pass filtering in digitalized receiver . the code - aided optimal filtering is studied extensively in the circumstance of oversampling and colored background noise 以往的扩频抗干扰文献多将扩频信号和背景热噪声假设为白噪声,由于在数字正交解扩解调中采用过采样和数字低通滤波,这一假设在数字化扩频接收机中并不成立。
