PDH

Example:While PDH is still in use, it is becoming increasingly obsolete and is often replaced with Classic SDH.

Definition:An older standard for synchronous digital hierarchical systems, which PDH was used to refer to before the establishment of modern SDH standards.

Example:Pseudo-synchronous standards including PDH are being phased out in favor of more modern systems.

Definition:A classification of communication systems that use PDH standards for digital signal transmission.