University:
College
Course:
College Engineering
Academic year:

2023
Views:

441

Pages:

3
Author:

Dipin K.

Spread Spectrum * The Importance chum is that it can provide protection against spread spectrum externally genuated intufering (jamming) signal with finite poure. This is done by spreading. Protection against Jamming Make the signal assxpуд minimum bandwidth necessary bandwidth far in to transmit it. excers of the Sigeal spreading frequery. BW Frequeny ie after spreading signal will have Thus the transmitted ignal appearance. Like vappuparna. undetected by a nose coill be able to propagate anyone. 50 spread spectrum signal is highly secure.communicatio." Spreading of signal will be done wing Sp PN. Sequence met? Tot) Desirise device orfres cct) mct)= bct) (1) Thushelt no. (bk) binary data Polas NRZ Signals [11] [CK] Prisequence bet) signal (C) PN signal. The spread spectrum modulation at the transmistes acheived by multiplying Ct) and bets using a product modulator multiplier. According to Fourier Trans form theory Mutiplication of signals produces a signal whose spectrum equals the convolution of the spectra of the two component agnals". Thus if the message bet) is narrow band and PNsignal wideband, the product signal met aill have a spectrum nearly the same as the wideband Pl signal. that le PN Sequence perform the role of spreading code. bit) [JCLE] [JC)] The transmitted signal mcts = C(t).bct). The received signal rets mets+ ilt) = ccxbq+ict) To Yecover dep despread the s -signal, the received signal res applied to a demodulator, followed by integrator of devision device Ac At the receives Z(t)=((+)-rct). Le *t)* PN sequence = (+).[mct)+ict)] = C(t) [((t) bustits] L = cts.bct)+((t). ICE). bets is multipled tovice by CLt). icts multiplied by cets only once. In the equation 2(t)=C²(+) bet)+cc+).ict) 2. cct) = 1 * Clitsis #1 so @24s will be always 1 So Zct = bct)+ ctx.ict) 1 is the ft team is the original data bet) 2hd term c(t).ict) power will be redured and cwhen icts multiplied with clt), its it coill be spreaded to a high bandwidth. in the team bct) + C(+).ict) bets is narrowband information signal C113-1(+) is spreaded wide band noise signal. So curing a filter (Integrator) we can recover the data. In the time durahón Otolb the result 'v' will be given ← the signal will be integrated and iven to decision device. The decision rale is if voo signal is V20 signalin le