Ever wonder How Internet is Connected all over the world

We all use internet in our daily lives now, internet is literally a part of our life now. Without internet we can’t do any work related to sending mails, downloading media, data transfer etc. well basically data transmission from one place to another is done by a server where data available and network helps in transferring its exact copy to another server.

But do you know how the data transfer from one far continent of the world to another far continent. Its a mind blowing fact lets know about it.

For Downloading data from server we want a connection between that server to the computer or device on which data is transferring, so this connection is applicable by network towers and server cable connection. Imagine that we have to download something from internet and the server of that data is placed in america and we have to download that in a computer which is placed in india, now how that data is transferred through america to india in seconds by which medium?

Well guys that medium is known as Submarine undersea Communication Cables.

Undersea cable

Undersea cable

A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean. The first submarine communications cables, laid in the 1850s, carried telegraphy traffic. Subsequent generations of cables carried telephone traffic, then data communications traffic. Modern cables use optical fiber technology to carry digital data, which includes telephone, Internet and private data traffic.

The First Cable Installation

In August 1850 John Watkins Brett’s Anglo-French Telegraph Company laid the first line across the English Channel, using the converted tug Goliath. It was simply a copper wire coated with gutta-percha, without any other protection, and was not successful.

The experiment served to secure renewal of the concession, and in September 1851, a protected core, or true, cable was laid by the reconstituted Submarine Telegraph Company from a government hulk, the Blazer, which was towed across the Channel.

First Cable to INDIA

Throughout the 1860s and 70’s, British cable expanded eastward, into the Mediterranean Sea and the Indian Ocean. An 1863 cable to Bombay, India (now Mumbai) provided a crucial link to Saudi Arabia. In 1870, Bombay was linked to London via submarine cable in a combined operation by four cable companies, at the behest of the British Government. In 1872, these four companies were combined to form the mammoth globespanning Eastern Telegraph Company, owned by John Pender.

The first trans-pacific cables were completed in 1902–03, linking the US mainland to Hawaii in 1902 and Guam to the Philippines in 1903. Canada, Australia, New Zealand and Fiji were also linked in 1902 with the trans-Pacific segment of the All Red Line.

Eighty-eight years later, the North Pacific Cable system was the first regenerative (repeatered) system to completely cross the Pacific from the US mainland to Japan. The US portion of NPC was manufactured in Portland, Oregon, from 1989 to 1991 at STC Submarine Systems, and later Alcatel Submarine Networks. The system was laid by Cable & Wireless Marine on the CS Cable Venture in 1991.

Construction of Cables

Transatlantic cables of the 19th century consisted of an outer layer of iron and later steel wire, wrapping India rubber, wrapping gutta-percha, which surrounded a multi-stranded copper wire at the core. The portions closest to each shore landing had additional protective armor wires. Gutta-Percha, a natural polymer similar to rubber, had nearly ideal properties for insulating submarine cables, with the exception of a rather high Dielectric constant which made cable capacitance high.

Gutta-percha was not replaced as a cable insulation until polyethylene was introduced in the 1930s. In the 1920s, the American military experimented with rubber-insulated cables as an alternative to gutta-percha, since American interests controlled significant supplies of rubber but no gutta-percha manufacturers.

Armoured Submarine cables

Carl Osborne, Tata’s VP of international network development, joined us to add his insights during the tour. When it comes to Tata’s submarine cable network, he has actually been on board the cable ship to watch it all happen. He brought with him some subsea cable samples to show how the design changes depending on the depth. The nearer to the surface you get, the more protection—armour—you need to withstand potential disturbances from shipping. Trenches are dug and cables buried in shallow waters coming up onto shore. At greater depths, though, areas such as the West European Basin, which is almost three miles from the surface, there’s no need for armour, as merchant shipping poses no threat at all to cables on the seabed.

Armoured cable intersection

Armoured cable intersection

At these depths, cable diameter is just 17mm, akin to a marker pen encased by a thick polyethylene insulating sheath. A copper conductor surrounds multiple strands of steel wire that protect the optical fibres at the core, which are inside a steel tube less than 3mm in diameter and cushioned in thixotropic jelly. Armoured cables have the same arrangement internally but are clad with one or more layers of galvanised steel wire, which is wrapped around the entire cable.

Without the copper conductor, you wouldn’t have a subsea cable. Fibre-optic technology is fast and seemingly capable of unlimited bandwidth, but it can’t cover long distances without a little help. Repeaters—effectively signal amplifiers—are required to boost the light transmission over the length of the fibre optic cable. This is easily achieved on land with local power, but on the ocean bed the amplifiers receive a DC voltage from the cable’s copper conductor. And where does that power come from? The cable landing sites at either end of the cable.

Fixing Cables in Sea

Cables are picked up by ships and bring to the repair station by cranes, because they are so heavy and placed deep under the sea.

Once the cable has been found and returned to the cable-repair ship, a new piece of undamaged cable is attached. The ROV [remotely operated vehicle] then returns to the seabed, finds the other end of the cable and makes the second join. It then uses a high-pressure water jet to bury the cable up to 1.5 metres under the seabed

Repairing of cables

Repairing of cables

Repairs normally take around 10 days from the moment the cable repair ship is launched, with four to five days spent at the location of the break. Fortunately, such incidents are rare: Virgin Media has only had to deal with two in the past seven years.

Technology Behind Submarine Cables

Submarine cable systems offer very high capacity up to 2 Tbps per cable. They have real time transmission along with very low bit error rates. The submarine transmission is known for having the best security of transmission. Submarine systems have optically amplified repeaters which are all photonic, meaning that no electronics exists in their transmission path. This allows for the simpler repeater construction to have a bit rate free from modulation and to use only low speed electronics.

Translantic Cable Network

The Transatlantic cable network runs under the Atlantic Ocean. As of 2012, there are a number of implemented transatlantic cables, both TAT and private non-TAT. There are currently two private non-TAT cables scheduled to be implemented this year.

Under sea cable network

Under sea cable network

The TAT-14 transatlantic fiber optic cable system started operating in 2001. As seen in Figure 4, the 15,428 km cable system connects the United States to the United Kingdom, France, The Netherlands, Germany, and Denmark by 10 Gbps Direct Wave Access (DWA) or STM-16, STM-4, and STM-1 interfaces. There are four fiber optic pairs configured for 47 x 10 Gbps DWDM channels of which 10 are utilized for dual, bi-directional SDH rings.

TAT-14 has a total design capacity or 3.2 Tbps calculated as: 2 (North & South Routes) x 4 Fiber Pair x 40 10 Gbps channels = 3.2 Tbps. TAT-14 has a total system capacity of 1.87 Tbps calculated as: Southern route: 41 x 10 Gbps channels + 640 Gbps SDH capacity, Northern route: 18 x 10 Gbps channels + 640 Gbps SDH capacity = 1.87 Tbps.



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