Elements of Comm.Sys Communication systems are electronic systems designed to transmit information Noise TRANSMITTER n(t) RECEIVER Information input Transmission Signal Carrier s( r(t Carrier Signal m() medium 11） processing circuits circuits processing (channel) iTo information sink(user) A waveform is basically a time-continuous signal,called analog signal. A seq of data is basically a time-discrete signal with finite values,called digital signal. UESTC-Introduction Prof李晓峰 5