说明：  本程序用于检测音频文件中是否具有DTMF信号，若有则将其检出。 程序首先使用Goertzel算法求出以FRAMESIZE（默认200）为大小的一帧数据在8个DTMF频点上的能量。 对Goertzel算法的改进，对于系数的计算不是采用2*cos[2*pi*k/N]，而是采用2*cos[2*pi*fn/fs],这样能够降低误差。 确定了8个频点的能量后运用一系列判决门限来确定有没有DTMF信号，以及信号是什么。
(This procedure used to detect whether an audio file with a DTMF signal, if so, what will be its detection. Procedures to derive the first use of Goertzel algorithm to FRAMESIZE [default 200] for the size of data in an eight point DTMF frequency energy. Of the Goertzel algorithm for the calculation of coefficients instead of 2* cos [2* pi* k/N], instead of using the 2* cos [2* pi* fn/fs], this can reduce the error. Identified eight frequency energy use after a series of sentences to determine the threshold has no DTMF signal, as well as the signal is.)