When the echo signal is unweighted, and the input frequency is just equal to an FFT bin frequency, the matched state is reached, the output SNR takes the maximum and the detectability is optimal.

• 当回波的输入信号未被加权，且其频率恰好等于FFT滤波器组的某一中心频率时，称为匹配状态，其输出信噪比最大，检测性能最好。