Channels and their characteristics Channel effects are: 1. Signal attenuation is due to loss in the media 2 Additive noise is essential for electronic systems.Electronic components such as resistors introduce noise,which often called thermal noise. 3.Bandwidth reflects how fast the media can follow the change of signals 4.Interference may be generated by nature and other systems,like thunders,signals of other users,spikes due to nearby car ignitions,etc. 5. Distortion of signal in amplitude or phase unflat UESTC-Introduction Prof李晓峰 6