C-band NLFM Pulse Radar System Design and Predistortion Technique to detect SDR based Transponder

Software Defined Radio (SDR) based transponder can take advantage of low cost, low complexity and flexible digital signal processing through on-board processor. It is also suitable for transmitting and receiving signals of relatively diverse frequency bands by adjusting internal LO and VGA gain and can perform various modulation processes at the baseband end. This study discusses the design of C-band NLFM pulse radar system for detecting and communicating SDR based transponders and the predistortion technique for system response linearization. Nonlinear frequency modulation (NLFM) waveform have utilized to suppress sidelobes level and chirp pulse radar topology have also used for SNR enhancement. Digital predistortion (DPD) technique was implemented to minimize nonlinearity of the radar system response. Amplitude weighting coefficients were calculated through acquired data on the transceiver board by performing system loop-back test. The coefficient was utilized to linearly compensate input signal for nonlinear radar system responses.