从普通PC声卡中产生出一对正弦波信号。可设置频率、幅度、相位差。当作信号发生器时，频率和相位差都有较高的精度，能满足一般要求-From the ordinary PC sound card produced a pair of sinusoidal signals. Can set the frequency, amplitude, phase difference. As a signal generator, the frequen