8.4 Spread spectrum communication systems 8.4.1 DSSS systems Chip,Te block diagram of a DSSS system is, symbol,Ts 几一0U m(0u① r(t) 8r(t 8r(T-t r0 0 t=T cos 2nft c(t) I(1) c(t) cos 2nft PSK modulator Channel- PSK demodulator A pseudo-noise or pseudo-random signal is a r noise-like signal generated from a noise-like data sequence,called PN code.c()is often given by c0=∑cnp-nI.) where {c,}is the binary PN codes of +1,p(1)is a rect-pulse of duration 7'called a chip UESTC-Wireless communicatons Prof李晓峰 7