Time Division Switching

In a single stage space division networks, a cross point-switching element is used to establish a specific connection between two subscribers. In space division networks, a conversation could be established via any one of the many alternative paths. In other words, a cross point is usable for establishing more than one connection. It is sharable among many subscribers. This sharing leads to a reduction in the number of switching elements required in the network. A switching element, once allotted, remains dedicated to a connection for its entire duration. As a result, sharing of a cross point occurs from one connection to the next. 

At a time, a cross point is required because continuous analog speech waveform is passed through the switch in space division switching. Switching element can be shared by a number of simultaneously active speech circuits. This is the principle of time division switching. Obviously, with the way the switching elements are shared in time division switching, much greater savings can be achieved in the number of switching elements when compared to multistage space division switching. 

Tele Communication

The field of telecommunication has evolved from a stage when signs, drum beats and semaphores were used for long distance communication to a stage when electrical, radio and Electro- optical signals are being used. Optical signals produced by laser sources and carried by ultra-pure glass fibers are recent additions to the field. 

Telecommunication networks carry information signals among entries which are geographically far apart. An entity may be a computer, a human being, facsimile machines, a data terminal and so on. Billions of such entities the world-over are involved in the process of information transfer which may be in the form of telephone conversation or a file transfer between two computers or a message transfer between two terminals, etc. 

In telephone conversation, the one who initiates the call is referred to as the calling subscriber and the one for whom the call is destined is the called subscriber. In other cases of information transfer, the communicating entities are known as source and destination, respectively.