Research Of Direct Digital Synthesis Technology Implementation

Direct Digital Frequency Synthesis (DDS) is a technology that synthesis directly required frequency departure from the concept of the phase. The normal structure includes frequency cumulation, phase addressing and low pass filter. It has great advantages of frequency stability, high frequency resolution, speed of frequency switching, simple analysis of phase noise and spurious, small size and low power. The Arbitrary Waveform Generators based on DDS technology have developed rapidly in recent years.This thesis mainly discusses the Direct Digital Frequency Synthesis (DDS) technique and its applications. Arbitrary Waveform Generator (AWG) designs which base on DDS technique are carried out through the FPGA platform and the ARM platform. The study is in-depth through the comparison between the different platforms.First of all, this thesis introduces the features of Direct Digital Frequency Synthesis (DDS) technique and gives a new structure of the Arbitrary Waveform Generators (AWG) base on DDS technology. This kind of AWG does not need to reload the ROM charts during changing the different types of waveform. The working principle and the technical performances of this AWG based on DDS technology are given. The design process and target parameters are Determined.Then, the ideal signal generator mathematical model is build and simulated. The main performance parameters of the AWG system are gained. The stray signals are analyzed in detail. This thesis also shows the noise model under the unideal situations. The main parts of the spurious signal contain: the error of phase calculation, extent error and unlinearity of DAC. This thesis counts the 3 parameters based on the noise model.Then, as a contrast, this thesis analyses the advantage and disadvantage between the different platforms, and determines the hardware to be used. Based on the ideal of model design as theory, this thesis also designs the function of the system which contains: frequency accumulation, phase addressing, output control and the charging of mode changing. The DDS signal generators are designed on the FPGA system and ARM system, the simulation results and download results are given and analysed in-depth.Finally, the design of the DDS signal generator based on the WinCE embedded operating system is shown. The transplant processes and design methods of mail hardwares and the whole customization processes of WinCE operation system are given. The thesis designed the application software based on the hardware and operation platform, and the the system is downloaded successfully. The results satisfied the design requirements. In addition, the thesis analyzes the remaining issues of the present DDS signal generator design under WinCE system and puts forward ideas to improve system performance.