Relevant knowledge of Submarine communications cable

The submarine optical cable is the "central nerve" of the Internet, carrying more than 90% of the world's international voice and data transmission. Without it, the Internet is just a local area network+

Submarine optical cables, like land optical cables, have fiber cores the size of hair strands inside. However, they require more reinforced armor protection and an important component - the remote power supply conductor, which transmits electricity to the submarine repeater.

The submarine optical cable system consists of two parts: onshore equipment and underwater equipment. The onshore equipment mainly includes optical cable terminal equipment, remote power supply equipment, line monitoring equipment, network management equipment, and grounding devices. Underwater equipment mainly includes optical cables, optical amplifiers/repeaters, and underwater branch units. The fiber optic cable terminal equipment is responsible for signal processing, transmission, and reception at both ends; The detection equipment includes alarm monitoring and fault location.

Although fiber optic has fast speed and sufficient bandwidth, due to attenuation, it cannot transmit signals without limitation. Therefore, in order to achieve long-distance transmission, a repeater (signal amplifier) needs to be added in the middle.

How to repair the broken Submarine communications cable?

The repair of submarine optical cables is very complex. In the vast ocean, it is necessary to find optical cables that are less than 10 centimeters deep and to determine the fault point, like looking for a needle in a haystack.

Firstly, the OTDR instrument needs to be used to locate the fault point, determine the specific location of the breakpoint, and then send an underwater robot (ROV) to cut the optical cable at the breakpoint. Then, the two ends of the optical cable are pulled onto the ship for fusion welding. This fusion process is quite complex because it requires the fusion of fibers with fine hair thickness in the optical cable one by one. After completing the fiber optic cable fusion, the repaired fiber optic cable is thrown into the sea and "buried", which means using a high-pressure water gun to flush out a trench of mud on the seabed, and then the repaired fiber optic cable is "placed" in. This process is also completed by the robot.

Category of Submarine communications cable

1. Number of conductive cores. It is mainly divided into three core submarine cables and single core submarine cables, with the majority of medium and low voltage lines using three core submarine cables and high voltage lines using single core submarine cables.

2. Transmission function. Traditional submarine cables only have a simple power transmission function, while new submarine cables belong to optoelectronic composite cables, effectively achieving the transmission of electrical energy and signals on the same cable line.

3. Load type. Divided into DC submarine cables and AC submarine cables, DC submarine cables are characterized by low losses and easy to achieve long-distance transmission. However, the application experience of DC submarine cables is not rich, and the construction cost of DC converter stations and other supporting facilities is high. AC submarine cables have high losses, but the operation and maintenance technology is mature and the supporting construction cost is small. Therefore, submarine cable line designers usually need to balance technology and economy to achieve maximum benefits.

Summary

The Submarine communications cable is an extraordinary achievement of human wisdom. They enable us to communicate across distant distances and bring us closer in ways that were once unimaginable. As our world becomes increasingly interconnected, we must continue to invest in this infrastructure to ensure it remains safe, reliable, and accessible to all.