Submarine communication system can be divided into submarine optical fiber cable communication system and no relay submarine communication system, there are relay submarine optical cable communication system is mainly composed of two parts underwater equipment and shore equipment. Underwater equipment mainly includes submarine optical cable, underwater optical repeater and underwater branch unit.

In addition to a similar submarine cable and terrestrial fiber cable as the main components of packaging and strengthen the power supply conductor;

Optical coupling by erbium doped fiber optical repeater, pump light source, coupler, wDM loop and oTDR pathway, submarine cable underwater device and connection casing, with monitoring and automatic protection function;

The realization of the branch and power supply switching of submarine optical fiber cable by underwater branch unit.



The shore equipment mainly includes the line terminal equipment, the SDH equipment, the remote power supply equipment, the line monitoring equipment, the network management equipment as well as the marine grounding device and so on.



Line terminal equipment for general DwDM equipment, responsible for the regeneration section of end-to-end communication signal processing, sending and receiving
;


SDH equipment carrying on line terminal equipment, in the case of ring network, forming a loop self-healing protection;



The remote power supply equipment through the cable conductor for feeding to the far and grounding device of submarine repeater backflow through seawater and marine, power supply current at 1 amperes, the supply voltage can be up to several thousand volts;



Line monitoring equipment automatically monitors the status of submarine optical cable and repeater, automatic alarm and fault location in the case of optical cable and repeater failure.



Where is the key technology of submarine communication?



Transmission system design technology.



The main factors that affect the performance of the transmission system are the signal to noise ratio, dispersion and nonlinearity. In order to overcome the influence of these factors on the submarine optical cable transmission system, it is necessary to overcome these problems by using special techniques and countermeasures, such as low noise optical amplification, forward error correction and dispersion compensation. In addition, the design of underwater repeater spacing is the key.



Underwater repeater technology.



Underwater optical repeater is a relay cable system the most important equipment, put forward very high requirements for equipment reliability requirements, service life for more than 25 years. In order to achieve high reliability, in order to achieve power, enlarge, at the same time, we need to consider the state monitoring, redundant backup of key components, etc.. The structure of the high volume requirements for small diameter suitable for laying, high water pressure seal. In addition, the device requires low power consumption, and consider the use of heat dissipation for a long time.



Remote power supply system technology.



Remote power supply technology is an important factor to control the transmission distance and the number of optical cable systems. The remote power supply system adopts DC voltage constant through the cable conductor to supply far for subsea equipment. The utility model can be used as a single end or two terminal power supply mode, and the other end of the utility model is automatically converted into a single end power supply when one end is in a fault mode. The parameter selection and design of power supply system, power supply scheme, backup scheme, fault and maintenance technology are difficult.



Line fault location and performance monitoring technology.



Circuit monitoring system comprising a network element management system and an undersea device. The network management system to realize the centralized monitoring station network element equipment, line monitoring system for detecting submarine repeater subsea equipment and optical fiber, optical cable and repeaters in case of fault line monitoring system, subsea equipment can automatically alarm and fault location.



Engineering construction technology.



The construction of submarine cable system by region construction, marine engineering, construction equipment and other conditions, the engineering construction relates to the technical field of extensive investment in large scale, complex construction technology. The project mainly involves design, cable routing, cable manufacturing and transportation; during the construction of systems engineering mainly includes cable route positioning, cable laying, cable protection, land, equipment installation, testing and debugging, project acceptance, the technology is complex and difficult.