Broadcast-quality television over SDH

The use of SDH networks to carry television signals raises issues of a totally different nature from those that arise with analogue networks. The SDH network has its own timing structure, and this must be reconciled with that of the television signals. `Mappings´ of signals into the SDH structure must be devised. A fixed-frame mapping for video signals is simple to instrument, and might be acceptable where the video sampling frequency is derived from a rubidium reference or the network itself. Otherwise, justification will be required within the container to avoid rates of pointer adjustment well in excess of expected network rates. Clock recovery and signal timing also raise potential problems. These have been discussed and several solutions proposed