Telephone network is the most effective and useful two way telecommunication system. With the help of a telephone, has other. The use of computers in telephones has added new dimensions to telecommunications. View data telescoping electronic banking electronic offices etc. are all born out of computers. In fact computers have added a new chapter to the phone network which has made communication systems very easy and fast.
How Phone Works:
When we speak our sound creates vibrations in the air. The microphone fitted in the mouth piece of the phone changes these sound waves into electric current. This current reaches the earpiece of the receiving phone through cable. In the ear piece of the phone, the electric current again changes to the original sound waves. In this way, your voice reaches the destination. This system is called analog broadcast because in this system, electric current is ‘analogous’ or identical to sound waves.
Digital Phone System:
The binary digital system was developed in 1960. in the digital phone system, sound signals are converted in the form of 0 and 1 which represent the on and off states. Binary digit is called a bit. Seven bits are generally used in telephone communications. The receiving phone coverts these digits back into sound waves. Binary digits are fast and are of the same kind, so it is very easy to convert the4m into their original form. Nowadays, these systems are used on a large scale along with computers.
Fiber Optic Cables:
Most of the phone calls travel through copper cables in the form of electric current, but nowadays these calls are also sent through optical fiber cables in the form of light. These cables have proved better than copper cables. Through this cable, about 10,000 telephone calls can be communicated at a time. In this system, laser beam and cable made of optical fibers are used.
The telephone system has not been totally digitalized in our country yet, only a few exchanges have been computerized. These exchanges control much more information in less time in comparison to the old mechanical exchanges. The chances of misconnections, crossed lines, interference or lost calls in these computerized exchanges are extremely low. Such exchanges also provide additional facilities like rerouting of a phone call for another phone, view data phone, number directories, automatic monitoring of call etc.
Cellular Radio and Telephones:
Cellular radios or telephones are used for mobile communications. Telephones remain linked with the cables and the person using the cordless phone can use it only within a cell of a few meters form the base station. In a few parts of big cities, special types of radio channels or transmitting frequencies are used. In cellular telephone network, an area is divided into many cells. Every cell is at a distance of five kilometers form each other. When a person using a cell phone makes a call, a radio signal is sent to the nearby base station. The base station sends it to the nearest mobile telephone exchange. After that, the call is automatically transferred from the transmitter of one cell to the other cell. In this system, many calls can be made simultaneously.