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(Goertzel algorithm is the core of DTMF signal detection. It uses the two-pole IIR filter to calculate the discrete Fourier transform value, and extracts the spectrum of input signal quickl