多通道多频高频地波雷达DDS数字信号源的设计

Design of Multi-Channel Multi-Frequency HF Ground Wave Radar DDS Digital Signal Generator

采用直接数字频率合成技术（DDS）产生多频高频地波雷达信号波形，使用现场可编程门阵列（field programmable gate array，FPGA）设计多通道多频高频地波雷达DDS数字信号源，提出了运用FPGA芯片实现该信号源的一种方案．该方案的系统组成包括PC机软件、LXI接口电路、控制模块、多通道DDS系统和加法器．该信号源输出为四通道单频信号及四通道信号加权叠加合成的多频信号．系统输出频率为3～30MHz，输出信号无杂散动态范围（SFDR）优于62dB，输出信号相位噪声优于132dB／Hz，实验结果可满足多频高频地波雷达发射和接收系统的要求．

The direct digital synthesis techniques （DDS） could often be used to generate multi-frequency HF ground wave radar signal waveform. Using the field programmable gate array （FPGA） to design the DDS signal generator is more flexible than the use of dedicated DDS chip. The FPGA chip is used in desig- ning the multi-channel multi-frequency HF ground wave radar DDS digital signal generator. This system could include the PC software, LXI interface circuit, control module, multi-channel DDS system, and the Adder Module. The output of the DDS signal generator will be four-channel single-frequency signal and multi-frequency signal which is synthesized by the four-channel. The output frequency band is 3-30 MHz. What is more, the output signal spurious-free dynamic range （SFDR） is better than 62 dB. Besides, the output signal phase noise is better than 132 dB/Hz. After the designing and the experimental testing, the DDS Signal Generator meets the requirements of transmitting and receiving system of Multi-Frequency HF Ground Wave Radar.