Please help me find the right device for an arbitrary waveform generator that can be programmed to do something like this: output a DC voltage, maintain it for a specified amount of time, superimpose a modulating signal over it with frequency swept between programmed values, stop the modulation, ramp the DC voltage to another level, apply a different modulation, etc. I am not sure whether a DDS device is the part suitable for this task. For example AD9913. Can these devices also generate a non-zero DC voltage and have modulation applied to it? Thank you.