Author Topic: History of telecommunication  (Read 1313 times)

Offline aman_diu

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History of telecommunication
« on: March 27, 2012, 06:17:09 PM »
A very early experiment in electrical telegraphy was an 'electrochemical' telegraph created by the German physician, anatomist and inventor Samuel Thomas von Sömmering in 1809, based on an earlier, less robust design of 1804 by Catalan polymath and scientist Francisco Salvá i Campillo.[5] Both their designs employed multiple wires (up to 35) in order to visually represent almost all Latin letters and numerals. Thus, messages could be conveyed electrically up to a few kilometers (in von Sömmering's design), with each of the telegraph receiver's wires immersed in a separate glass tube of acid. An electrical current was sequentially applied by the sender through the various wires representing each digit of a message; at the recipient's end the currents electrolysed the acid in the tubes in sequence, releasing streams of hydrogen bubbles next to each associated letter or numeral. The telegraph receiver's operator would visually observe the bubbles and could then record the transmitted message, albeit at a very low baud rate.[5] The principal disadvantage to the system was its prohibitive cost, due to having to manufacture and string-up the multiple wire circuits it employed, as opposed to the single wire (with ground return) used by later telegraphs.

The first commercial electrical telegraph was constructed in England by Sir Charles Wheatstone and Sir William Fothergill Cooke. It used the deflection of needles to represent messages and started operating over twenty-one kilometres (thirteen miles) of the Great Western Railway on 9 April 1839. Both Wheatstone and Cooke viewed their device as "an improvement to the [existing] electromagnetic telegraph" not as a new device.

On the other side of the Atlantic Ocean, Samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837. Soon after he was joined by Alfred Vail who developed the register — a telegraph terminal that integrated a logging device for recording messages to paper tape. This was demonstrated successfully over three miles (five kilometres) on 6 January 1838 and eventually over forty miles (sixty-four kilometres) between Washington, DC and Baltimore on 24 May 1844. The patented invention proved lucrative and by 1851 telegraph lines in the United States spanned over 20,000 miles (32,000 kilometres).[6]

The first successful transatlantic telegraph cable was completed on 27 July 1866, allowing transatlantic telecommunication for the first time. Earlier transatlantic cables installed in 1857 and 1858 only operated for a few days or weeks before they failed.[7] The international use of the telegraph has sometimes been dubbed the "Victorian Internet".[8]

The electric telephone was invented in the 1870s, based on earlier work with harmonic (multi-signal) telegraphs. The first commercial telephone services were set up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London. Alexander Graham Bell held the master patent for the telephone that was needed for such services in both countries. The technology grew quickly from this point, with inter-city lines being built and telephone exchanges in every major city of the United States by the mid-1880s.[9][10][11] Despite this, transatlantic voice communication remained impossible for customers until January 7, 1927 when a connection was established using radio. However no cable connection existed until TAT-1 was inaugurated on September 25, 1956 providing 36 telephone circuits.[12]

In 1880, Bell and co-inventor Charles Sumner Tainter conducted the world's first wireless telephone call via modulated lightbeams projected by photophones. The scientific principles of their invention would not be utilized for several decades, when they were first deployed in military and fiber-optic communications.
md. Aman Ullah
B.sc in ETE
121-19-1366
Daffodil International. University

Offline arefin

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Re: History of telecommunication
« Reply #1 on: March 29, 2012, 10:35:24 AM »
Thanks
“Allahumma inni as'aluka 'Ilman naafi'an, wa rizqan tayyiban, wa 'amalan mutaqabbalan”

O Allah! I ask You for knowledge that is of benefit, a good provision and deeds that will be accepted. [Ibne Majah & Others]
.............................
Taslim Arefin
Assistant Professor
Dept. of ETE, FE
DIU

Offline aman_diu

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Re: History of telecommunication
« Reply #2 on: April 11, 2012, 05:20:18 PM »
welcome sir
md. Aman Ullah
B.sc in ETE
121-19-1366
Daffodil International. University

Offline nayeemfaruqui

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Re: History of telecommunication
« Reply #3 on: May 16, 2012, 01:36:28 PM »
Informative post
Dr. A. Nayeem Faruqui
Assistant Professor, Department of Textile Engineering, DIU

Offline mhasan

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Re: History of telecommunication
« Reply #4 on: June 18, 2012, 08:05:41 PM »
Good one.
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MM Hasan
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Daffodil International University
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