在数字信号接收中，滤波器的作用有两个方面，使滤波器输出有用信号成分可能强；抑制信号带外噪声，使滤波器输出噪声成分可能小，减少噪声对信号判决的影响。对最佳线性滤波器称为匹配滤波器。在数字通信中，匹配滤波器具有广泛的应用。因此匹配滤波器是指滤波器的性能与信号的特征取某种一致，使滤波器输出端的信号瞬时功率与噪声平均功率的比值最大。(In the digital signal reception, the function of the filter has two aspects, which makes the output of the filter useful signal strong; suppresses the noise from the signal out of band, makes the filter output noise component small, and reduces the effect of noise on the signal decision. The best linear filter is called a matched filter. In digital communication, matched filter is widely applied. Therefore, the matching filter means that the performance of the filter is consistent with the characteristic of the signal, which makes the ratio of the instantaneous power of the signal at the output of the filter and the average power of the noise maximum.)