Tag Archive: history

Continued… Part V– Comparing Old & New + How Submarine Cables Work

Yesterday I discuss on the comparison of the components/materials used to construct the submarine telecommunications cable between the early days and present (modern days).

Today, I’ll further compare the capacity between the early days and present (modern days) submarine telecommunications cable system in its respective era as follows:

Old Cable Systems:

  • 1866: First trans-Atlantic cable carried telegraph messages at 7 words a minute & cost £20 for 20 word message
  • 1948: Telegram costs reduced to 4 pence a word for transmission across the Atlantic
  • 1956: First trans-Atlantic telephone cable (TAT-1) initially had capacity of 36 telephone calls at a time; calls costing US$12 for first 3 minutes

Modern Cable Systems:

  • 1988: First Atlantic fiber-optic cable, TAT-8, had capacity for 40,000 simultaneous phone calls, 10 times that of the last copper cable
  • Today: Each fiber pair within a cable has the capacity to carry digitized information (including video) that is equivalent to 150,000,000 simultaneous phone calls. Wow!

Knowing that the modern days sub-cables deliver the data much significantly than early days, we may wonder how these submarine cables work.

How Submarine Cables Work

  • Modern submarine telecommunications cables rely on a property of pure glass fibers, whereby light is
    transmitted by internal reflection
  • Because the light signal loses strength en route, repeaters are installed along the cable to boost the signal
  • New systems rely on optical amplifiers – glass strands containing the element, erbium. Strands are spliced at intervals along a cable & then energized by lasers that cause erbium-doped fibers to “lase” & boost optical signals

Based on the above, a typical submarine cable system is depicted on the following diagram.

Typical Submarine Cable System

Typical Submarine Cable System

>> Follow the following link to download free a bigger image size (960×703):

(File Name: http://www.ziddu.com/download/10632377/Typical_Submarine_Cable_System_watermark.png.html )

Source: International Cable Protection Committee Ltd

To be continued… Part VI– Cable Size and Comparing Submarine Cables vs Satellite.


Continued… Part III – Sub-Cable Network Familiarization (History)

To familiar with Submarine Cable Network, let’s start with the most important component of the network/system that is Submarine Telecommunications Cables.

For today post, I’ll discuss on a brief history of Submarine Telecommunications Cables so that we can have a better understanding from the history perspective. The era of seabed cables began around 1850, when the first international telegraph cable was laid across the English Channel.

  • 1840-1850: telegraph cables laid in rivers & harbors; limited life, improved with use of gutta percha insulation c.1843
Harvesting gutta percha resin

Harvesting gutta percha resin

  • 1850-1851: 1 st international telegraph link, connecting England-France across the English Channel, later cables joined other European countries & USA with Canada
Cables from UK-France link in 1850 (a) and 1851 (b)

Cables from UK-France link in 1850 (a) and 1851 (b)

  • 1858: 1st trans-Atlantic cable laid by Great Eastern, between Ireland & Newfoundland. Unfortunately this cable lasted only a few days before it was cut by a curious fisherman who thought he had discovered a new kind of seaweed and wanted to take a sample.  Failed after 26 days & new cable laid in 1866.
Great Eastern off Newfoundland c. 1858

Great Eastern off Newfoundland c. 1858

Atlantic cable 1866

Atlantic cable 1866

  • 1884: First underwater telephone cable service from San Francisco to Oakland
  • 1920s: Short-wave radio superseded cables for voice, picture & telex traffic, but capacity limited & subject to atmospheric effects
  • 1956: Invention of repeaters (1940s) & their use in TAT-1, the 1 st trans-Atlantic telephone cable, began era of rapid reliable communications
  • 1961: Beginning of high quality, global network
  • 1986: First international fiber-optic cable joins Belgium & UK
  • 1988: First trans-oceanic fibre-optic system (TAT-8) begins service in the Atlantic

Source: International Cable Protection Committee Ltd

To be continued… Part IV– Sub-Cable Network Familiarization (Sub-Cable Components)

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