脉冲发生测试.此程序为AD9850（DDS）直接数字频率合成器C语言源码。用125M的有源晶振，频率无失真输出可达到40M。-Impulse test. This procedure for the AD9850 (DDS) Direct Digital Frequency Synthesizer C language source code. With 125M active crystal, the frequency output can be achieved without disto