What is a PDH system?

Time : Jan. 31, 2023    View : 40

PDH, or Plesiochronous Digital Hierarchy, is a technology used to transmit digital signals over telecommunication networks. It is widely used in modern communications systems for carrying voice, video, and data signals over long distances.


In a PDH system, data is transmitted as a series of digital pulses over a dedicated circuit. The digital signals are sent in parallel across multiple paths, allowing multiple signals to be transmitted simultaneously over a single communication link. This results in greater bandwidth utilization and more efficient use of network resources compared to older technologies such as analog circuits.

pdh system

One of the key benefits of PDH technology is its support for high-speed data transmission. PDH systems can support data rates of up to 2.048 Mbps, making them suitable for applications such as video and high-definition image transmission. Additionally, a typical PDH system can support multiple channels, enabling multiple signals to be transmitted over a single communication link.


A PDH system consists of several components including a multiplexer, a demultiplexer, and a regenerator. The multiplexer combines multiple signals into a single signal, while the demultiplexer separates the combined signal back into its individual components. The regenerator is used to improve the quality of the signal as it travels over long distances.


PDH systems are widely used in a range of applications, including point-to-point circuits, metropolitan area networks, and wide area networks (WANs). In a WAN, a PDH system can support data transmission over distances of up to 2,500 kilometers.


However, PDH systems have some disadvantages, including higher complexity and higher costs compared to older technologies. Additionally, data is transmitted in time slots of fixed duration, typically 125 microseconds, which can result in some delay in the transmission of data.


Despite these limitations, the global market for PDH systems is expected to grow at a compound annual growth rate (CAGR) of 7% between 2020 and 2030, driven by the increasing demand for bandwidth and the rollout of 5G networks.


In conclusion, PDH systems play an important role in modern telecommunications networks. They provide greater bandwidth utilization, improved signal quality, and better overall performance compared to older technologies. However, organizations need to carefully consider the costs and benefits of adopting PDH technology before making a decision to invest in this technology.