【正文】 ormation bandwidth of 300Hz 3400Hz, television image information bandwidth of order to make full use of 3 frequency resources, which are roughly the same as far as possible the signal bandwidth to transmit the radio munication bandwidth RF signals with the mass of information is parable to the as the AM signal used to transmit voice messages, voice messages of their bandwidth for twice the bandwidth。Chirp frequency system is a linear extension of the process of of a number of ways of hybrid systems are often applied. 2 The most important measure of spreadspectrum system is an indicator of spreading gain, also known as processing is precisely because of the spread spectrum system itself with its performance characteristics with a series of advantages. The purpose of spread spectrum munication studies and significance Spread spectrum munication is an important branch of munication and channel the direction of development of munication technology, with strong antiinterference ability, confidentiality, and is easy to realize the advantages of multipleaccess munications, so the technology is receiving increasing recent years, with very large scale integrated circuit technology, the rapid development of microprocessor technology, as well as the application of some new ponents, spread spectrum munications is technically feasible to enter a new level, not only in an important military munications status, and are quickly perated into the personal munications and puter munications and other civilian areas, to bee the new century, the most potential of munication study is spread spectrum munication with farreaching significance, I through the thesis the design, conduct indepth study of the spread spectrum munication technology and its applications for simulation, knowledge will be summarized and summed in order to consolidate the basic knowledge of munications for the After the individual to lay a foundation to study and work. 2 The basic principles of spread spectrum munication The definition of spread spectrum munication The socalled spread spectrum munications, can be simply expressed as follows:Spread spectrum munication technology is a means of information transmission,Share some of its signal bandwidth is much larger than the minimum mass of information necessary bandwidth。Frequencyhopping system using pseudorandom code to control the carrier frequency in a wider band of the change。 Spread Spectrum Communication System and MATLAB Simulation ABSTRACT This thesis expounds the basic principles of spread spectrum munication , and then the article mainly acts according to the Shannon theorem and tan oak Czechoslovakia you Nepal may the husband latent antijamming theory,With the aid of MatLab toolbox and Monte Carlo simulation algorithm,it has established the direct sequence spread spectrum munications system simulation model which does not have when the disturbance through the analysis error rate simulation curve and theory predicted value,had proven constructs the simulation model the accuracy. Key words： Spread spectrum； munication； MATLAB 1 Introduction Spread Spectrum Communication System Spread spectrum munication, namely, spread spectrum munications (Spread Spectrum Communication), with fiberoptic munications, satellite munications, with access to the information age as the three major hightech munications spectrum munication is to send the information to be pseudorandom data is coded (spread spectrum sequence: Spread Sequence) modulation, spread spectrum and then the realization of transmission。 the receiving end is using the same modem code and related processing, the restoration of the original spectrum munication system has three main characteristics. Carrier is an unpredictable, or socalled pseudorandom broadband signal. Carrier data bandwidth than the modulation bandwidth is much wider. Receiving process is generated by local broadband carrier signal and receiving a copy of the signal to the broadband signal to achieve. The main way of spread spectrum are as follows:Direct Sequence Spread Spectrum (DSSS) using highspeed pseudorandom code on to the lowspeed data transmission spread spectrum modulation。TH is the data transmission time slot is a pseudorandom。The expansion of the band through a separate code sequence to plete, using the method of coding and modulation to achieve, with the mass of information has nothing to do。Television broadcasting RF signal bandwidth is only the video signal bandwidth more than are among the narrowband FM signal, or pulse code modulation signals, their bandwidth and the information ratio of bandwidth to only a few spectrum munication signals and information bandwidth than the bandwidth of up to 100 1000, belonging to broadband use such a wideband signal to transmit information? Do not waste valuable resources in the frequency of it? 2)The use of spreadspectrum code sequence modulation signal approach to broadening the spectrum. We know that in time limited signal, its spectrum is example, very narrow pulses, the spectrum is very bandwidth is inversely proportional to its approximate microsecond pulse bandwidth is about , if the use of limited and narrow pulse sequence has been modulated by the mass of information it may give rise to very broadband described in the following direct sequence spread spectrum system is the method used to obtain spread spectrum signals. This very narrow pulse sequences, the code rate is very high, as the spreading code be noted here that the spreading codes used by the mass and sequence data is not relevant, that is to say it and in general the same si