[help] How Can I simulate a basic DDS ?

How can I simulate a basic DDS(direct digital synthesizer) ?

I have tried to use Matlab and simulink,in fact I really built a basic DDS,but the problem is I don't know how to analyze the spectrum of the DDS.I used the spectrum tool of the simulink,but I can't get the correct result.

Someone suggest me to simulate the dds using SystemView,but I have never used SystemView before......

Who can give me an example?

I dont you that whether you try to use fix-point representation on simulink. What exactly you expect from the spectrum?