STUDY OF FREQUENCY HOPPED SPREAD SPECTRUM SYSTEM UNDER PARTIAL BAND NOISE JAMMING

Abstract

Spread-spectrum systems have been developed since about the mid - 1950's. The initial applications have been in the military anti jamming tactical communications, to guidance systems and to experimental antimultipath systems. It is being used now-a-days in commercial applications as well as in measurement and test equipments. 1.1 THE CONCEPT OF SPREAD SPECTRUM [1,2,3] By definition 113] "Spread Spectrum is a means of transmission in which the signal occupies a bandwidth in excess of the minimum necessary to send the information, the band spread is accomplished by means of a code which Is independent of data, and a synchronized reception with the code at the receiver is used for despreading and subsequent data recovery". According to the above definition PM. PCM and FM which also spread the spectrum of an Information signal do not qualify as spread the spectrum because the increase in bandwidth of the signal Is determined by the information signal. Process gain is the parameter which Is normally used to specify the quality of spread spectrum system. The process gain of spread spectrum (SS) system is the difference of output signal-to-noise ratio and input signal-to-noise ratio. It may be estimated by rule of thumb:..