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History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network

Cable Signalling Speed and Traffic Capacity

The Atlantic Cable website often receives requests for historical data on signalling speed and traffic capacity of long distance cables, so I've summarized here some improvements in cables over the last 150 years. The majority of cables listed are Atlantic crossings to give consistency to the results.

Cable Year Speed or Capacity
Atlantic, Ireland-Newfoundland 1858 A few words per hour
Atlantic, Ireland-Newfoundland 1866 6 - 8 words per minute
Long cables with automatic transmitting equipment 1898 40 words per minute
Newfoundland-Azores 1928 2,500 characters per minute (~400 wpm)
Atlantic, TAT-1
(first repeatered cable)
1956 36 telephone channels
Atlantic, TAT-2 1959 48 telephone channels
Atlantic, CANTAT 1961 80 telephone channels
Atlantic, TAT-3 1963 138 telephone channels
Atlantic, TAT-4 1965 138 telephone channels
Atlantic, TAT-5 1970 845 telephone channels
Atlantic, TAT-6 1976 4,000 telephone channels

Note: In 1978, before the inauguration of TAT-7, an article in the Times noted that:
“More than half of all international telephone calls between Britain and the rest of the world go by undersea communications circuits.”
The rest were transmitted by satellite, but with the advent in 1988 of TAT-8, the first transatlantic fiber optic cable, the balance moved rapidly to cable. Since then, satellite has played only a relatively minor role, as the article went on to predict.
[Pearce Wright. “Cable and satellite systems maintain rivalry.” Times (London, England) 4 Apr. 1978: IV.]

Atlantic, TAT-7 1978 4,000 telephone channels
Atlantic, TAT-8
(first fiber-optic cable)
1988 280 Mbit/s (40,000 telephone channels)
Atlantic, TAT-9 1992 2 x 565 Mbit/s (each 80,000 telephone channels equivalent)
Atlantic, TAT-10 1992 2 x 565 Mbit/s
Atlantic, TAT-11 1993 2 x 565 Mbit/s
Atlantic, TAT-12/13 1996 2 x 5 Gbit/s
Atlantic, TAT-14 2001 4 x 16 x 10 Gbit/s, 640 Gbit/s system capacity (9,700,000 telephone channels equivalent).
Note: TAT-14 has four fiber pairs, each carrying 16 wavelengths. Each wavelength carries a 9.6 (nominally 10) G signal, giving a 640 Gbit/s total capacity.
Atlantic, VSNL (TGN) 2001 2 x 2,520 Gbit/s
Hibernia Atlantic (cable commissioned in 2001 and partially upgraded in 2007) 2007 10 Gbit/s on transatlantic section, 40 Gbit/s from Boston to Nova Scotia.
System capacity 1.9Tb/s, 7.68Tb/s on upgraded section
Atlantic, GTT Express (formerly Hibernia Express) 2015 100 Gb/s x 100 wavelengths. Maximum capacity 53 Tb/s

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Last revised: 5 March, 2020

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Research Material Needed

The Atlantic Cable website is non-commercial, and its mission is to make available on line as much information as possible.

You can help - if you have cable material, old or new, please contact me. Cable samples, instruments, documents, brochures, souvenir books, photographs, family stories, all are valuable to researchers and historians.

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—Bill Burns, publisher and webmaster: