What is Communication ?
Communication is the process of establishing connection (or link) between two points for information exchange.
In our day to day life we come across many ways of communicate. For communication to take place, three essential things must be present.
Sender or Transmitter : It sends information. For example TV transmitting station or radio transmitting stations are ‘senders’, since they transmit information.
Receiver : It receives information. For example all TV sets and radios are receivers. They get information from transmitter.
Communication Channel : This is the path through which the signal propagates from transmitter to receiver. shows an example of communication system.
Now let us consider different examples of communicate that we use in our day to day life.
All of us use telephones now a days. We know that we talk and listen through a telephone. The telephone set is connected to telephone exchange through wires. The other telephones are connected in the same way.
As shown in Fig the transmission is bidirectional. Every telephone subscriber can talk as well as listen. Talking is equivalent to transmission of data (voice) and listening is equivalent to receiving of data. The data (voice signal) is passed through wires. Thus the communicate channel contains wires which are routed through telephone exchange.
Mobile phones (Cellular phones) :
As we know, the mobile phones are becoming very much popular now a days. In the mobile phones also we can talk and listen. Thus mobile subscribers are essentially talkers (transmitters) and listeners, (receivers).
As shown in the Fig, the mobile phone subscribers communicate to the base stations in their cell. Therefore two mobile subscribers communicate with each other through the base stations. Base station is similar to telephone exchange which work in particular area. But there are no wires joining the mobile phone subscribers and base stations. Thus the voice signals pass through air. Air acts as the conducting medium. This is also called wireless communicate. The communication channel is the air (wireless).