Optimal design of digital IF processing in HFGWR

Software radio has become the focus of research in communication. Radar based on software radio technology overcomes the simplification and inflexibility of conventional radar. Digital IF, one of its key technologies, is a typical application of multi-rate signal processing theory. The paper studies the high decimation ratio of the digital downconverter in HF ground wave radar (HFGWR), and especially analyzes a multi-stage decimation algorithm based on CIC (cascaded integrator-comb) filter and HB (half-band) filter. In comparison with the single stage polyphase design, the optimal design can save 92.6% of the logic resources, and it can be well implemented in one DSP chip (such as ADSP21062) for four receiver channels. Furthermore, the filtering performance is better than the design requirements.