Signal Processing And Implementation Of Waveform Generation For Stepped Frequency Radar

As an instantaneous narrowband and synthetic wideband waveform, stepped frequencyradar signal has been widely employed in many applications. It allows high rangeresolution with modest requirements of the receiver A/D sampling frequency. In this paper,research on the key signal processing methods and implementation of waveform generationin the stepped frequency radar is mainly discussed as follows:Firstly, the processing methods in the stepped frequency radar signal are studied fromtwo points of views with frequency-time and time-frequency transformations. Then, theeffects due to target motion on the processing are analyzed, and the velocity estimationmethod based on cross-correlation of range performance is discussed with detail simulation.Then, the design of stepped frequency signal waveform constraints is analyzed, and theparameter design criteria of HPRF PD stepped frequency radar is given. Finally, a methodof phase difference is proposed to resolve range ambiguity, the waveform to obtain bothunambiguous velocity and high resolution ranging is derived and verified with simulation.Secondly, aiming at the detection and imaging of targets in interference, the uniqueanti-clutter characteristic of the stepped frequency radar is firstly analyzed. Then thedifferent location of folded clutter and motion target in IDFT HRRP is discussed, anddifferent target detection method is proposed due to different speed. The simulation resultsindicate that the methods are feasible. At last, the good anti-interference capability ofstepped frequency radar to active interference such as sighting frequency narrowbandinterference, broadband noise interference and RF memory repeater interference etc. arestudied and simulated.Finally, the basic theory of using direct digital frequency synthesis (DDS) technologyto generate stepped frequency signal is researched. Then two hardware design based onDDS chip and DAC chip are implemented and the DDS boards are programmed anddebugged. At last, the experimental results using one of the radar system are presented.