8.4 Spread spectrum communication systems 8.4.1 DSSS systems Chip,Te block diagram of a DSSS system is, symbol,Ts 一L0 m⑥v)u① r(t) 8r(T-t) r20 0 t=T a cos 2nft c(t) I(t) c(t) c0s2对ft PSK modulator Channel→ PSK demodulator What happen in SPECTUM? B≈T Spread-factor: B.≈T Bne =B+Be L= B 、 Brsk B T UESTC-Wireless communicatons Prof李晓峰 9