Browsing by Author "Elmabruk, Kholoud Khaled"

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Citation Count: ELMABRUK, K.K. (2012). Design of a jammer for spread spectrum signal using matlab simulation. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü.
Design of a jammer for spread spectrum signal using matlab simulation
(2012) Elmabruk, Kholoud Khaled
The term spread spectrum is today one of the most popular terms in the radio engineering and communication community. Since, code division multiple access “CDMA” is a form of spread spectrum, a family of digital communication techniques that have been used in military applications for many years. Originally there were two motivations: either to resist enemy efforts to jam the communications “anti-jam, or AJ”, or to hide the fact that communication was even taking place, sometimes called low probability of intercept “LPI”. It has a history that goes back to the early days of World War II. In the late 1940's the proposed theoretically use of CDMA for civilian mobile radio applications is novel, but the practical application in the civilian marketplace did not take place until 40 years later. Nowadays, because of the dramatic growth of using the communication devices in every day’s life, and since this usage is sometimes has to be disturbed for some reasons, so to achieve this jammers are used. In practice, many types of jammers such as partial band noise jammer, pulsed noise jammer, and single-tone jammer are used. While this thesis studies the jammer design differently, by using the same spreading codes which spreads the message signals. This thesis addresses a study of designing a jammer for spread spectrum signal by analyzing the performance of the system using the MATLAB simulation. To achieve this, after a brief introduction the principles of the spread spectrum systems are explained in details, then the techniques of the detection which are used to retrieve the message signal are presented. Finally, the implementation of the design based on using the same spreading codes, which are used by the jammed system itself. Each of Gold, PN, and Kasami codes is used not only to spread the message signals but also to jam them. The channel is assumed to be an Additive White Gaussian Noise “AWGN”, and the suboptimum detector is used to retrieve the messages. According to the simulation results the designed jammer perform close to the theoretical jammer at a low signal to noise ration “SNR”, and increasing the code length diverge the designed jammer from the theoretical, in contrast the effect of increasing the number of users is opposite.