| Spread Spectrum communication takes an important part in military communication and in civil communication. Especially in recent years, code-division multiple access(CDMA) system based on spread spectrum communication is widely used in mobile communication.Software radio is a new kind of wireless communication structure. Its basic idea is that on a fixed hardware, man can download different software to realize different modulating patterns. When doing this, the change and upgrade of the system are convenient and cheap, and different systems can communicate effectively.This paper brings forward the idea that we can combine Tame Spread-Spectrum technology and software radio technology in one military communication system. Such system is compatible, and it is difficult to be jammed. The paper also analyzed the mathematic model of software radio structure and its three kinds of structures, and compared the advantages and disadvantages of each kind. On the basis of the third kind structure(the modulator in simulative field) , the paper gave out a method to realize the software radio digital hardware modulator which can perform the function of ASK, PSK, DPSK, MASK, QPSK, DQPSK, QAM, OQPSK modulations, using the apparatus of DSP and CPLD. The test showed that the modulator can meet the request of system design. Modulators of the other two kind software structures and some advanced modulating patterns are also worth being studied.
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