Elements of Comm.Sys Communication systems are electronic systems designed to transmit information Noise TRANSMITTER n(t) RECEIVER Information input Transmission Signal Carrier s(I r() Carrier Signal m(:) medium 11） processing circuits circuits processing (channel) ITo information sink(user) Transmitter:A device that converts the infor into a signal that matches the channel. 通 Eg.To send an AM radio signal,you have to move the voice into the band at some freq,say 1000kHz. UESTC-Introduction Prof李晓峰 7