Discuss the basic structure and principle of operation of Time Slot Interchange (TSI) switch with the help of a neat diagram.

Principle of time slot interchange

 Time slot interchange

CM = Control Memory;

DM = Data Memory

Time multiplexed time switch allows time slot inter changing. In time slot inter changes, a speech sample input throughout one time slot may be sent to the output through a various time slot. This operation essentially implies a delay in between the transmission and the reception of the sample.

This operation can be described with reference to above given figure.

1. M channels are multiplexed on each trunk

2. The time slot duration is specified by t_TS =125/M. The time slot counter is increased at the end of each time slot. The content of the counter gives location address for data memory and control memory.

3. Control memory and data memory accesses take place concurrently in the beginning of the time slot. After that, the contents of the control memory are utilized as the address of the data memory and the data read out for the output trunk

4. The input sample is obtainable for reading in at the starting of the time slot and the sample is set to be clocked in on the output stream at the end of the time slot.