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(ty Carrier Signal m() processing medium 1) circuits circuits processing (channel) iTo information sink(user) Receiver:picks up signals in the channel and recovers information;then delivers it to user. The process of extracting information from the modulated signal is called demodulation. signal-correction and noise-suppression are important work in the receiver. UESTC-Introduction Prof李晓峰 9