COMMUNICATION

Communication wich a computer transfers data, instruction and information to another computers. Its a sending and recieving device.Conversations through signals and signal to data. The Uses of communications are: E-mail,voice e-mail,fax,telecommuting,videoconferencing, groupware,global positioning system,bulletin board system and Internet. Use of communications at internet are: The web,E-commerce,telephony,structure of the internet animation. About channels it has "transmission media"in this there are two: Physical and wireless.In physical their are 3 cables :Twisted pair ,Coaxial
and Fiber optic.In wireless there are 5:Broadcast radio,Cellular radio,microwaves,communication satellite and infrared.

The transmission characteristic are:Signal type: analog or digital,Transmission modes:Asynchronous or Synchronous,Transmission direction:Simplex, half duplex and full duplex,and Transmission rates 

COMMUNICATION NETWORK (PART 2)
About the computer device first the modem, it has internal , external and fax.Second cable modem,it has CATV,External,Internal and Set-top box.Third is Multiplexers,combines a lot of data streams in one..The fourth is Network Interface card,enabling a PC or printer to connect a network.The fifth is connecting network,it has Hub ,repeater, bridge,gateway and router.