Richard writes: While working on a project I came across the DDS chips from Analog Devices. Especially the AD9835 was very atractive to me because of its super simple handling and small size. Normaly you would use such a chip as a VFO or for other, similar functions but I decided to use it as a “Soundcard” for a project to do various digital RF modes with a PIC microcontroler. Some would say “I can do this with just the PIC and dont need a DDS chip”. That’s true but you would waste a lot of program memory for things like sine tables etc. With this solution you will have more memory available for your programs and you will get better signals than you could produce with just the PIC.
A DDS Module based on the AD9835: [Link]