Evaluating Tributary Jitter from the SDH Network

In the long term, the synchronous SDH network may develop to the state where asynchronous networks will only exist at the periphery of the synchronous network, and all transport through the network is on SDH. However, this is an ideal model that may not be prevalent until well into the next century. At present, and during this intervening period as the SDH network evolves, the hybrid synchronous/asynchro-nous network will predominate. Thus a signal may experience several synchronous/asynchro-nous conversions during its passage through the network. As SDH equipment is installed in the network, SDH islands will appear. Initially, these SDH islands are likely to be point-to-point networks. As the SDH portions of the network increase, these islands will merge to form larger more sophisticated islands consisting of not only Path Terminating Equipment (PTE) but also Add/Drop Multiplexers (ADM), Digital Cross-connect Systems (DCS), etc. As the tributary signal traverses these larger SDH islands as part of an VC, phase and/or frequency differences between SDH network elements will induce pointer activity in the SDH signal.