PDH Meaning and
Definition
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PDH stands for Plesiochronous Digital Hierarchy. It is a telecommunications system that is used for transmitting digital signals across a digital network. PDH was widely deployed in the 1980s and 1990s to carry voice and data traffic.
PDH is a hierarchical structure that consists of multiple levels, with each level representing a specific rate of data transmission. These levels are commonly referred to as E1, E2, E3, and so on, where E1 is the lowest rate and E4 is the highest. Each level is further divided into time slots, allowing multiple signals to be multiplexed together in a time-division multiplexing (TDM) fashion.
One of the key features of PDH is its plesiochronous nature, which means that the clocks used by different devices in the network are not perfectly synchronized. Despite this lack of perfect synchronization, PDH ensures that the timing of each signal is accurately maintained by inserting additional bits known as stuff bits. These bits are used to compensate for the differences in timing between the transmitting and receiving devices.
PDH has largely been replaced by the more advanced and flexible technology known as synchronous digital hierarchy (SDH) or SONET (Synchronous Optical Networking) in modern telecommunications networks. However, PDH is still used in certain specific applications and regions where SDH infrastructure has not been widely adopted.
Common Misspellings for PDH
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