AD9833的扫频程序，实现连续没有中间横线的扫频。注意：AD9833有个切换的平滑功能，但是由于平滑时输出为中间直流，所以会有一条线，但这样打扫频平滑，关闭平滑后，没中间的直流，但会跳。-The AD9833 sweep program, and continuous with no intermediate horizontal sweep.Note: the AD9833 switch smoothing function, but

Intermediate DC output smoothing, so there will be a line, but this cleaning frequency smoothing, after smoothing is turned off, not the middle of DC,

But will jump.