Delta-sigma-based Radar Waveform

With the development of digital technique, digital radar has received broad application.The radar waveform generation has run to digital technique from analogue technique.The waveform generation based Delta-Sigma modulator use oversampling and noise shaping technique, can acquire analogue waveform with high SNR by 1 bit D/A converter. This technique overcome the disadvantage of the current methods based PCM which always has high spurious and can be used as an alternative to current methods for LO and RF transmission waveform production. The dissertation discuss the key technology of Delta-Sigma waveform generation, including: the theory and structure of Delta-Sigma Modulator; the stability analizing and optimization for high order modulator; the structure of bandpass modulator. A test board based FPGA has been designed to verify the waveform generation technology based Delta-Sigma modulation. The test board transfers wave data from PC by USB2.0, can generate a 2.488GHz 1 bit stream. The board realizes the waveform generation based lowpass or bandpass modulator with a sample rate of 2.488GHz, can be used to generate the baseband I,Q waveform or IF waveform.The main work in this dissertation is as follows:1.The noise transfer function of high order lowpass and bandpass modulator have been designed and the simulation of the modulator has been completed.2.A scheme of 1 bit Delta-Sigma waveform generation system with a 2.488GHz sample rate has been presented.3.The scheme graph and PCB design of the test board have been completed.4.The timing design of the test board has been completed.5. The hardware's debug of test board has been completed and the testing results have been given.