Initial Improvements And Implement For Chip STEL-2000A Based On FPGA

In general wireless communication mobile systems, to minimize the transmission bandwidth is the goal of modulation and demodulation schemes. On the contrary, the spread spectrum technology expands the spectrum of the signal for transmission. The actual bandwidth of the spread spectrum signal is often several orders higher than the narrowband signal. However, some other advantages of it allow many users to use the same bandwidth simultaneously but do not interfere with each other. Therefore, the spread spectrum technology is usually used in multi-user systems which bandwidth efficiency is very high and have strong anti-jamming,anti-multipath capability.The main module of the spread spectrum system is generally realized by spread spectrum communication chips. Limited by the semiconductor manufacturing and the restriction of the design level, the production of these chips is late in China and the applications mainly focus on the remote tracking,intelligent home appliances and other civilian areas. At present, most applications still adopt foreign chips, even in defense projects. Taking into account the issue of the national security and the flexibility of chips, many projects which achieve the function of spread spectrum communication chips based on FPGA are implemented.In the paper, the widely used chip STEL-2000A is studied. A simple spread spectrum communication system is realized based on Xilinx's Virtex-Ⅱpro platform. Each module and the entire system are tested including the functional simulation and the timing simulation. The emphasis of this thesis are presenting the detailed matched filter module amplitude error analysis and proposing a more optimized approximate formula. In addition, a new look-up table method is proposed for the differential demodulator. The new method not only achieves the correct differential demodulation function but also is simple to realize,reduces the amount of computation and resource consumption which fully demonstrate the advantages of the improved method.