The Electronic Switching systems are operated with the help of a processor or a computer which control the switching timings. The instructions are programmed and stored on a processor or computer that control the operations. This method of storing the programs on a processor or computer is called the Stored Program Control (SPC) technology. New facilities can be added to a SPC system by changing the control program.
The switching scheme used by the electronic switching systems may be either Space Division Switching or Time Division Switching. In space division switching, a dedicated path is established between the calling and the called subscribers for the entire duration of the call. In time division switching, sampled values of speech signals are transferred at fixed intervals.
The time division switching may be analog or digital. In analog switching, the sampled voltage levels are transmitted as they are. However, in binary switching, they are binary coded and transmitted. If the coded values are transferred during the same time interval from input to output, the technique is called Space Switching. If the values are stored and transferred to the output at a time interval, the technique is called Time Switching. A time division digital switch may also be designed by using a combination of space and time switching techniques.
