Research On Programmable Signal Generator Based On DDS Technology

Digital direct frequency synthesis(DDS) is a new frequency synthesis technique introduced in early 70s, its digital structure meets many requirements of modern electronic system, so this technique grows rapidly. Using single-chip microcomputer, this paper developes a new function waveform generator. The paper discusses the realization of sine wave, square wave, triangle wave signal and various parameters of the signal waveform control,the application of tree-like data structure to achieve dynamic menu, the realization of intelligent people machine dialogue.Firstly, the development of frequency synthesis technique is expounded, various kinds frequency synthesis technique's feature is compared, at last, present situation and development trends of DDS are introduced.Secondly, basic theories and mathematical synthesis of DDS are introduced, what's more, ideal frequency spectrum and nonideal frequency spectrum of DDS technique are analyzed.Thirdly, design proposal of supply oscillator and implementations of software and hardware are bring up on the basis of theoretical research. Hardware circuit divides the whole system into several parts: single-chip microcomputer control and interface circuit, AD9835 chip, wave filtering, amplitude control, waveform conversion, waveform select and other modules. Every module is given elementary diagram and is analyzed.Finally, software is compiled by Keil C language in order to realize motion menu, keyboard scan, waveform select, frequency system conversion, AD9835 interface call, FSK frequency register select, amplitude stepping increase and decrease interface call and other functions.The experimental result shows that multi-waveform supply oscillator designed in this paper based on DDS technique meets preliminary design requirements.