Goertzel算法是DTMF信号检测的核心，它利用二极点的IIR滤波器计算离散傅立叶变换值，快速有效的提取输入信号的频谱信息。-Goertzel algorithm algorithm is DTMF signal detection at the core, It uses two poles of the IIR filter calculating the discrete Fourier transform value rapid and effective extraction of the input signal spectrum of information.