Design And Implementation Of Baseband Signal Processor For The Multi-mode IFF Interrogator

The IFF(Identificator of Friend or Foe) achieves the recognition of thecharacteristics of friend or foe by the following steps.First, the interrogator transmits aseries of RF pulses, then the target equipped with a transponder recieves the pulses andreplys, and this way is based on secondary radar technology. And this is the main way toidentify friend or foe at home and abroad. Therefore, the research and analysis of IFFbased on sencondary radar technology are very important.The main content of the thesis contains the background information of IFF,secondary radar system, the hardware structure of the baseband processor system andthe analysis and implementation of the baseband processing algorithm. The system canprocess most modes of sencondary signal such as mode1, mode2, mode3/A, mode C,mode4and mode5. The signal processing is based on the FPGA+DSP hardwarestructure. The generation of interrogation sinal, detection of effective pulse position,rising edge and falling edge, decomposition of pulse and frame detection are completedin FPGA. And the functions of dephantom, defruit, extracting code, analyzing theconfidence of the code, RS coding/codec, Walsh coding/codec and communicationsecurity encryption/decryption are implemented in DSP. After tested, the basebandsignal processor can generate interrogation signals and process the replys in accordancewith the design requirements stably. Particularly, the response processing system canobtain desired effect in high-density environment where frames are seriouslyoverlapped.