Based On Generic Software Radio Modulation, Despreading Demodulator,

Software Radio (SWR) is a kind of new radio communication architecture which was first proposed in 90's in last century. Its basic idea is to realize all kinds of radio communication functions by software programming based on a programmed hardware platform which is all-purpose, standardized and modularized. Then new functions can be easily realized by adding, amending and upgrading the software.An all-purpose modem has been designed, which is based on the idea of Software Radio. Signal can be transmitted in DS/D8PSK, DS/DQPSK or DS/DBPSK by this modem. Both the digital circuit and analog circuit have been used in the modulator. The modulator can be implemented easily by this method, and achieve better performance. The FPGA and DSP architecture has been used in the digital correlator, by which the spread spectrum signal can be demodulated at the intermediate frequency. The modem not only can work at the current transmission mode, but also can be upgraded in future.The primary content in the paper is as follow:In Chapter 1, it introduces the theory of the anti-jamming and spread spectrum technology. Then the background of the project and the task I did have been presented.In Chapter 2, it introduces the basic theory of the Software Radio, which includes the architecture of Software Radio, the sampling theory and multi-rate signal process.In Chapter 3, the algorithm of modulation and demodulation has been given.In Chapter 4, it introduces the hardware frame of the modem, which includes some chips'introduction and the implementation of some key circuit.In Chapter 5, the problem appeared in debugging has been analyzed. Then the testing result of the modem has been given.Finally, a conclusion of the whole paper is drawn, discussing the advantages and disadvantages of the modem.