通过计算DTMF信号的DFT对DTMF信号进行检测，在给定8个频率上的能量对信号进行测量，同时判断出每个频率对应的DFT的频率采样点。-By computing the DFT of the DTMF signals to detect the DTMF signals, measurement of the signal energy in eight frequency given, determine the frequency of sampling points for each frequency corresponding to the DFT.