Applied Research On Digital Technology In MMW High Resolution Radar System

Stepped Frequency Radar (SFR) is a type of one dimension high range resolution radarprovided with wideband by using frequency-field- synthesizing method. It characterizesinstantaneous narrow band signal, but synthesized wide-band signal, thus makes dataacquisition and signal processing easier.Radar digitization is a trend of radar development. Application study of digital techniqueapplied in millimeter wave high resolution radar is a necessary requisition of modern radartechnique.This dissertation gives a completely survey to digital technique application in radar (radardigitization technique) and the technological research approach of radar digitization. Itpoints out that radar digitization includes replacing analog components with digitalalternatives, digital signal generation,digital beam forming and digital signal processing,etc.This dissertation presents a new method of generating complex waveforms of frequencystepped pulse and CHIRP with DDS technology. When designing the MMW HRR homingsystem, CHIRP wave form with great time-bandwidth product(125) and short time pulseare used in the same system to solve the incompatible problem of long rafige detection andshort range blind area, greatly enlarge the radar homing system's operating scope. Whenadopting Digital Down Conversion (DDC), in the band pass sampling process millimeterwave down conversion is made at the same time, so made it easy to realize in engineering,The optimum sampling frequency of band pass sampling are calculated and optimized. Soby using the state-of-art integrated circuit MMW direct sampling is realized. Only oneA/D converter is needed to complete complex quadrature translation and digital downconversion, get in-phase component and quadrature component in digital field, and also,after intra-pulse compression is done, the signal-to-noise ratio is raised, and inter-pulsecompression is done in digital field, and finally, high range resolution profile is got.Two-step stretch processing method for MMW high-resolution RADAR is presented.On the basis of theoretical research, this dissertation presents control method of DDSdevice, control. DDS chip with a microcontroller, produce the baseband pulse of linearfrequency modulation (Chirp), integrate stepped-frequency pulse with Chirp, realizeself-adaptation switch-over between two kinds of wave forms, and experimental resultsare presented. Implementation of inter-pulses costas FH high resolution MMW radarsignal using dds technology is included.