Research Of Wideband Signal Generation Based On Interpolation Digitaly

As the development of modern military technology,the challenge the radar facing is increasing,thus the development of wideband radar technology has become an important developing direction, and the wideband waveform generation will become an essential research part.Wideband radar requires that signal has wide inpulse width, bandwidth as well as high stability and arbitrary shape.The modern DDS-based waveform generation technology has the advantage of high frequency and phase resolution, high stability and programmable. It meets the needs of modern radar’s waveform generation.This thesis studied two methods of wideband signals generation based on digital interpolation technique, including quadrature modulation after interpolation of baseband signal and bandpass filtering after interpolation of low-IF wideband signal, and finished simulation and comparison of the two methods through specific design examples, additionally FPGA simulation for the first method. The main work is as follows:1.Under the request of wide-band and high-IF, proposed improvements for the structure of quadrature modulation after baseband interpolation, achieved a multi-channel quadrature modulation structure based on polyphase theory and made improvements for polyphase filter using it’s symmetry.2. For a specific example,finished FPGA simulation of the advanced structure, completed simulation of every individual modules.3. Proposed a new method of wideband signal generation,it’s based on bandpass filtering after interpolation of low-IF wideband signal.Deduced the designing parameter of the low-IF signal, proposed it’s high-efficient polyphase structure, finishd the theoretical simulation of this new generation.4. Comparished the two methods, and analysised their adaptation conditions.