单音多频信号的产生和识别，采用FFT变换。应用于电话拨号。是学习数字信号处理的大作业。-Tone multi-frequency signal generation and recognition, the use of FFT transform. Applies to telephone dial-up. Digital Signal Processing is the study of large operations.

DDS芯片AD9914编程，产生单音信号，双音信号以及调幅调相信号。 -AD9914 DDS chip programming, generating tone signal, dual tone signal, and the amplitude and phase signals.