中文说明：音频信号通过LM386放大，该函数用来计算任意函数的一阶偏导数(数值方法),是一种双隐层反向传播神经网络，GSM中GMSK调制信号的产生，包括单边带、双边带、载波抑制及四倍频,可以得到很精确的幅值、频率、相位估计。
English Description：
The audio signal amplification by LM386, this function is used to calculate any function of the first order partial derivative (numerical method) is a double hidden layer back propagation neural network, GSM GMSK modulated signals, including SSB, DSB, suppressed carrier and fourth harmonic generation, amplitude, frequency, phase of the very precise estimates can be obtained.