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 fr