Based Fpga Digital Frequency Synthesis Systems Design And Implementation,

This work is beforehand studies work that Chinese aerospace science and technology group the seventh institute, mainly take XX radar as background, produce the jump frequency signal and the chirp signal that XX radar need. This project examines the significance of the pre-research by this master Coherent Frequency Hopping Synthesizer key technology for the enterprise high-performance full coherent follow-up radar system transmitting and receiving signals of high purity and other weak signal capability to provide technical support, In the anti-clutter, with the frequency of asynchronous, active interference, to provide some technical support, comprehensive system for the follow-up frequency engineering technical reserves, enhance their own R & D capability.The main contents of this project is through the direct digital synthesis (DDS) + direct analog frequency (DS) mode hybrid synthesizer reference signal of the full realization of coherent, low phase noise, low spurious, high frequency agility and generation lines Of frequency hopping signals. The project is divided into two parts, both digital and analog. In this thesis, the digital part, some of the major figures from the two AD9852 chips and an FPGA chip composition.This thesis introduces the development of the frequency synthesizer, FPGA-based implementation described the significance of DDS technology; then introduces the basic theory of DDS; then introduced the basics of FPGA, such as structural features, development processes, tools, etc; then introduced the use of FPGA realization of direct digital frequency synthesis (DDS) in principle, circuit structure, optimization methods. Focus on DDS technology implementations in the FPGA in the given part of the VHDL source. First, the process of software generated chirp signal process design, process design frequency hopping signal generator. Then follow the process design algorithms to calculate specific AD9852 have different cycles, different pulse width of chirp and frequency hopping signals required work mode state, the starting frequency, frequency increment, the amount of frequency step, and the frequency of the initial dose, frequency increment, the frequency step into the frequency control word in hexadecimal and tabulation, the chirp signal through the FPGA and the frequency hopping signal control word table exists FPGA-ROM. LFM signal generation and frequency hopping process, FPGA look-up table according to the frequency control word using the appropriate method to remove from the ROM in accordance with the frequency control word is written prior agreement of the timing relationships DDS, the AD9852 to achieve through the FPGA software control of the output signal process.Designed by the digital frequency synthesizer with high-performance, cost-effective, simple circuit structure and other characteristics; Finally, physical hardware, photos and test results, test results show that the system can meet the design requirements of the indicators, a good FH signal generating complete and chirp signals.