Digital Spectrum Analyzer, The Baseband Processor Is Designed To Transform,

In this dissertation, the design details of a baseband converter are presented. This converter is to join the RF receiver in the SHAO VLBI Station and the S80S1024 Digital Correlation Spectrometer, the joint is aimed to realize the single antenna observation of molecule spectral line.The converter system adopt super-heterodyne structure and image rejection structure toward different bandwidth. System included a PLL synthesizer, mixers, filters, amplifiers, attenuators, and a clock signal generator. According to the requirement of the input and output, each part is analyzed and proved.The theory of frequency synthesizer, mixer and filter is simply but adequately introduced first. Then, the design of each part in the system is expatiated. Some test data and problems are discussed at last.