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Subsea and terrestrial cables are emerging in a new form with huge benefits in a range of applications.
Known as the “backbone” of the Internet, there are currently about 486 submarine cables under construction or under construction, with more than 1,300 landings and stretching over a million kilometers. Their terrestrial counterparts have greater distances.
Optical fibers are at the heart of the internet, enabling the vast communications of people, devices and computers, from just a few meters away, such as data centers and campuses, to vast distances spanning continents and oceans. However, the story doesn’t end there.
fiber optic cable
The telecommunications industry is rapidly ditching copper wires in favor of fiber-optic cables — filaments of pure glass — each no thicker than a human hair, which help transmit light over long distances. Every piece of data sent or received on a computer and almost every call we make is transmitted over fiber optics. Even cell phone communications depend on it. Only the last few kilometers are carried out by air.
For the past 60 years, engineers have been exploring the possibility of using optical fibers as sensors.
“Engineers and scientists have known about the extraordinary opportunities of fiber optic sensing since the early days. With the first patent for fiber optic sensing dating back to 1960, the most imaginative minds have been exploring the many exciting possibilities it has to offer for decades. possibilities,” said Matteo Lonardi, a research engineer at Nokia Bell Labs.
data highway
As the world enters the digital age and the internet becomes ubiquitous, the key enablers of this change remain hidden from view. By road and rail, buried in seabeds and trenches, or in pipes laid under city streets and buildings, fiber optic cable networks converge to form the data superhighway that handles more than 95 percent of the world’s telecommunications traffic.
It’s a long way from the days of undersea seismographs (OBS) to salvage the days when undersea earthquakes caused huge tsunamis and delivered information to the show in seconds.
The most important technology driving fiber-optic sensing is Distributed Acoustic Sensing (DAS), which allows real-time measurements along the full length of the cable. Unlike traditional instruments that rely on sensors operating at predetermined points, distributed sensing utilizes the cable itself to sense the environment.
light pulse
In short, a DAS interrogator attached to one end of the fiber sends out a pulse of light and looks at the light returning from every microscopic part of the fiber, a process called Rayleigh backscattering. By collecting these tiny sheets of light and seeing how they change thousands of times per second due to nearby vibrations, the interrogator identifies unique signatures and flags each type of event.
DAS is a specialized sensor that detects acoustic events around an optical fiber. It requires specialized hardware, and sometimes even specialized fiber — not used for telecommunications. “DAS itself does not play an active role in data transmission or communications, but can be placed next to communication lines or networks to protect fiber assets or locate cuts,” said Dan Danskin, DAS Commercial Manager, Alcatel Submarine Networks (ASN).
In addition to DAS, there are some non-specialized sensors that perform different tasks, but retain the ability of intelligent sensing. Combined with fiber optics, coherent repeaters are the basic building blocks of any modern optical transmission. Thanks to coherent modulation and digital signal processing, they convert electrical signals into optical signals and vice versa, transmitting and receiving hundreds of gigabits per second. When receiving an optical signal, the transponder will perform several advanced algorithms to remove any channel damage added during fiber optic transmission to reconstruct the original sent message.
Forwarder
Additionally, in current and future generations of transponders in the Nokia 1830 PSS product, in addition to sending and receiving hundreds of gigabits per second, the transponders will perform advanced Monitoring, sensing and analytics. signal processing. The sole purpose of coherent transponders is not to sense, but to take advantage of advances in digital signal processing to extract sensing and monitoring information without the need for specialized hardware or fiber optics.
Sensing application
Telecom fiber optics are both critical infrastructure requiring constant monitoring and potentially globally distributed sensors. Perceiving the environment provides information that has a dual purpose. It can help identify potential cyber threats or outages and provide information about areas where other sensors are sparse.
A significant advantage of fiber optic sensing is monitoring cables, which often travel through rough terrain and moving seabeds. For example, coherent transponders can help monitor the entire cable infrastructure against any signs of failure and optimize capacity.
Severe weather phenomena such as storms, earthquakes or construction work that can damage the fiber can be sensed using special tools or directly on the transponder. The result is faster recovery, greater uptime and superior service quality.
Repair submarine cables
Repairing submarine cables is dangerous and expensive. Early and accurate detection of disturbances, failures or damage is critical for seamless service continuity. An advanced cable monitoring system can help direct personnel to the exact location of an incident for timely intervention.
Cables also need to be protected from human activities such as trawling, anchoring and dredging. Sensors can detect vibrations from fishing nets being dragged along the coastal bed. Trawling poses a huge threat to submarine cables, accounting for about 70 percent of network damage. Early warning will give the cable operator time to radio the vessel and ask it to move off the cable.
Fiber optics can even be used for environmental and scientific monitoring of earthquakes and tsunamis. The existing network of submarine cables can effectively be transformed into a huge array of sensors that, once connected to a seismograph-based network, could dramatically improve global seismic monitoring at an affordable cost. In addition to this, fiber optics can monitor various ocean conditions, such as ocean currents and rockslides, and can also help track mammals.
monitoring pipeline
In terms of onshore cable sensing, DAS is widely used to monitor onshore pipelines, including leak detection, external disturbance and ground motion monitoring. It can be used for perimeter protection and border control of critical assets.
By using existing fiber optic cable networks in urban areas, DAS can provide a sensing grid for high-resolution traffic monitoring and road conditions. Railway monitoring is another emerging field. With fiber optic cables along the track, DAS can provide information about moving trains, detect third-party activity, and locate rocks and landslides.
Opportunities and Challenges
One of the main challenges that the industry needs to address is managing data, after weighing the enormous opportunities that fiber optics presents. Monitoring and sensing in modern optical networks can generate unprecedented amounts of information. The problem at hand is processing massive amounts of data to extract meaningful signals.
Appropriate tools, such as artificial intelligence and machine learning (AI/ML), can be used to remove noise from raw sensory data and automatically detect and track events of interest. It must work dynamically as new threats emerge and ensure strict adherence to the established rules governing the decision-making process.
The proliferation of optical networks
Due to the massive popularity of optical networking, monitoring and sensing could prove to be the next big thing. A technology with a positive and meaningful impact that helps reduce and control risk through early detection of fires, storms and earthquakes. It could even play an active role in combating the impacts of climate change by making communities smarter and safer. — arab trade news agency
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