written 2.4 years ago by |
When a pulse of 'Tb' secs duration is transmitted through a band limited channel, the pulse appearing at o/p is dispersed or expanded having duration greater than 'Tb'.
As the received pulses are extended, when a train of pulses gets transmitted, each pulse interference with the adjacent pulse transmitted over the channel.
This interference is over the adjacents symbols, hence the name Inter symbol Interference.
Due to ISI, determination of a symbol as 1 or 0 is difficult at receiving end.
In multiplexed systems such TDMA, cross talk can take place due to over lapping of adjacent pulses, i.e. ISI.
- ISI Removal:
Since pulse dispersion is the property of the channel, it cannot be completely eliminated.
To avoid the effects of ISI, elements with negative dispersion can be added to the channel, i.e. change the channel property.
Use of Repeaters will allow system to reconstruct the pulses.