Research On Baseband Conversion Algorithm Of VLBI Data Acquisition Terminal

The international VLBI digital baseband conversion terminal technologies are more mature than them in China.This paper first introduces the research status of digital data acquisition terminal in China and foreigns.Then it elaborates the basic theories needed in research data acquisition terminal baseband conversion algorithm,and points out that it is necessary to research efficient baseband conversion algorithm.In order to realize the full probability acquisition,the implementation scheme of channelized receiver based on the polyphase filter is proposed.This implementation scheme divide the signal into some channels in frequency domain,convert the signal to the base-band signal in digital down converter and send the base-band signal to the data analyzing computer.The most difficult work is to design the algorithm of the digital down converter.In this paper,Matlab is used to verify the polyphase filter based on the odd and even arrangement of the complex signals.By comparing the input and output signals,the effectiveness of the algorithm is verified.Then the polyphase filter of the complex signal in even and odd arrangement is realized by FPGA.After the processed of the output signal,we found that the function of the polyphase filter bank is achieved successfully.