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“Since its invention in 1876 the telephone evolved
along with the technology of the time. Not only was there an evolution
in the instruments but many different manufacturers produced various
styles and a certain uniqueness to their wall and desk telephones”
Morse, Samuel Finley Breese (1791-1872), American artist and inventor,
known for his invention of the electric telegraph and the Morse code.
Morse was born in Charlestown (now part of Boston), Massachusetts, on
April 27, 1791, and educated at Yale College (now Yale University). He
studied painting in London and became a successful portrait painter and
sculptor. In 1825 he helped found the National Academy of Design in New
York, and the following year he became the first president of the
institution. He continued his painting and became a professor of
painting and sculpture at New York University in 1832. At about that
time he became interested in chemical and electrical experiments and
developed apparatus for an electromagnetic telegraph that he completed
in 1836. The following year he filed a caveat, or legal notice, at the
Patent Office in Washington, D.C., and tried without success to obtain
European patents for his apparatus. He also invented a code, now known
as the Morse code, for use with his telegraph instrument.
In 1843 the Congress of the United States appropriated US$30,000 for
Morse to construct an experimental telegraph line between Washington,
D.C., and Baltimore, Maryland. The line was successfully installed, and
on May 24, 1844, Morse sent the first message: “What hath God wrought!”
Morse was subsequently involved in much litigation over his claim to
the invention of the telegraph, and the courts decided in his favour.
He received many honours. Later he experimented with submarine cable
telegraphy.
Morse died in New York on April 2, 1872.
Bell, Alexander Graham (1847-1922), British-born American inventor and
teacher of the deaf, most famous for his invention of the telephone.
Bell was born on March 3, 1847, in Edinburgh, and was educated at the
universities of Edinburgh and London. He emigrated to Canada in 1870
and to the United States in 1871. In the United States he began
teaching deaf mutes, publicizing the system called visible speech. The
system, which was developed by his father, the Scottish educator
Alexander Melville Bell, shows how the lips, tongue, and throat are
used in the articulation of sound. In 1872 Bell founded a school for
deaf mutes in Boston, Massachusetts. The school subsequently became
part of Boston University, where Bell was appointed Professor of Vocal
Physiology. He became a naturalized US citizen in 1882.
Since the age of 18 Bell had been working on the idea of transmitting
speech. In 1874, while working on a multiple telegraph, he developed
the basic ideas for the telephone. His experiments with his assistant
Thomas Watson finally proved successful on March 10, 1876, when the
first complete sentence was transmitted: “Watson, come here; I want
you”. Subsequent demonstrations, particularly one at the 1876
Centennial Exposition in Philadelphia, Pennsylvania, introduced the
telephone to the world and led to the organization of the Bell
Telephone Company in 1877.
He died on August 2, 1922, at Baddeck, where the Canadian government
maintains a museum containing many of his original inventions.
Morse Code, International, system of signals employed in
radiotelegraphy in the land-telegraph systems of all countries except
the United States and Canada, and by all countries in flash lamp
communications in marine navigation. The system is an adaptation of
Morse code, the original telegraph alphabet devised by the American
inventor Samuel F. B. Morse. When other countries adopted the
International Morse Code for sending radiotelegraphy messages in the
1850s, the United States and Canada continued to use the original Morse
code. International Morse Code consists of combinations of dots and
dashes representing the letters of the alphabet and numerals, as shown
in the accompanying table. The duration of one dash equals that of
three dots. Today, International Morse Code is rarely used, because
radiotelegraphy has been replaced by printing telegraph systems, and
facsimile transmission. The international code of signals however, is
still used to ensure the safety of navigation and people at sea.
Telephone
Communication instrument designed to transmit speech and other sounds
to a distant point by means of electricity, and to reproduce them.
The telephone contains a diaphragm, which vibrates when struck by sound
waves. The vibrations (wave motion) are converted into electrical
impulses and transmitted to a receiver, which converts the impulses
back into sound.
In common usage, the term “telephone” is also applied in a much broader
sense to the entire system to which an individual telephone set is
connected; a system which allows the sending of not only a user’s voice
but also data, pictures, or any other information which can somehow be
encoded and converted into electrical energy. This information is
exchanged between points connected to the network. The telephone
network consists of all of the transmission paths between subscriber’s
sets and of the switching machinery used to select a particular path or
group of paths between subscribers.
Parts of a Telephone Set
A basic telephone set contains a transmitter, receiver, dial, ringer,
and antisidetone network as electrical parts. (This use of the word
“network” refers to a small assembly of electrical components inside
the set and should not be confused with “network” in “telephone
network” which refers to the global interconnected system). If it is a
two-piece set, the transmitter and receiver are mounted in the handset,
the ringer is typically in the base, and the dial and antisidetone
network may be in either the base or handset but are usually together.
More sophisticated telephones will have a microphone and speaker in the
base in addition to the transmitter and receiver in the handset. In a
cordless phone the handset cord is replaced by a radio link between the
handset and base but a line cord is still used. A cellular phone is
often a one piece unit in which extremely miniaturized components make
it possible to combine the base and handset into one handheld unit that
communicates with a distant radio station. No line or handset cords are
needed, providing the ultimate in portability.
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The invention of the carbon telephone transmitter by Emile Berliner was
the key to a practical telephone.
Today, most telephones have pushbuttons instead of a rotary dial.
Because Touch Tone was introduced as an optional premium cost service
the exchange has to maintain the ability to receive either pulse or
multitone dialing. Since a person buying a telephone might have a line
on which multifrequency signals are not accepted by the telephone
company, pushbutton telephones usually have a switch which the customer
can set to determine whether the telephone will send pulses or tones.
Transoceanic Telephony
Overseas radio-telephone service was introduced commercially in 1927,
but the problem of amplification prevented the laying of telephone
cables until 1956, when the world’s first transoceanic submarine
telephone cable, extending between Newfoundland and Scotland, was
placed in service.
Microwave Relay
In this method of transmission, radio waves generally in the
superhigh-frequency band, called microwaves, are relayed from station
to station. Because the transmission of microwaves requires a clear
line of sight between sending and receiving stations, the average
distance between relay stations is about 40 km (25 mi). As many as 600
telephone conversations can be transmitted over one microwave relay
channel.
Satellite Telephony
In 1969 the first global telephone relay network was completed with a
series of satellites in stationary orbits 35,880 km (22,300 mi) above
the Earth. These satellites are powered by solar energy cells. Calls
transmitted from an Earth antenna are amplified and retransmitted to
distant ground stations. The integration of satellite and terrestrial
facilities allows calls to be routed between continents as easily as
between domestic points. Thanks in large part to digitization of
transmissions, satellites of the global Intelsat series can relay up to
33,000 calls simultaneously as well as several television channels.
One satellite would not serve for a call from New York to Hong Kong,
for example, but two would. Even considering the expense of a satellite
such a path is cheaper to install and maintain per channel than the
equivalent path using coaxial cables on the ocean floor. Consequently,
as much use is made as possible of satellite links in long distance.
Satellites do have one serious shortcoming, however. Because of the
satellite’s distance and the finite speed of radio waves, there is a
noticeable lag in conversational responses. Because of this, many calls
will only use a satellite for one direction of transmission (say from
New York to San Francisco) and will use a ground microwave or coaxial
link for the opposite direction. The participants in a call from New
York to Hong Kong might be annoyed if carried over a two satellite link
in both directions because they would find it difficult to
interrupt—which is a normal occurrence in speech. They would also be
bothered by the long time (over a second) it took the other party to
respond after each had finished speaking.
Video Telephone
A two-way video telephone was first demonstrated in 1930 by the
American inventor Herbert Eugene Ives in New York. The video telephone
can be linked with a computer for displaying reports, charts, and
schedules over long distances. It also enables face-to-face meetings of
callers in different cities and can serve as a link between conference
centers in a network of major cities. Video telephones are now
commercially available and can be used on domestic lines for
face-to-face calls. Similar features are also now viable between
suitably equipped personal computers.
Cellular Mobile Communication
Cellular, or mobile phones, originally used in cars, airliners, and
passenger trains, but increasingly becoming ubiquitous, are basically
low-power radio-telephones. Calls go through radio transmitters that
are located within small geographical units called cells. Because each
cell’s signals are too weak to interfere with those of other cells
operating on the same frequencies, more channels can be used than would
be possible with high-power radio frequency transmission. Narrow-band
frequency modulation (FM) is the most common mode of transmission, and
each message is assigned a carrier unique to the cell from which it is
transmitted. Since the cellular phone was first tested in 1978, the
cellular market in Britain alone had grown at a rapid rate to over 8.5
million users by 1997. In Japan it is as high as one mobile phone per
ten people. However, while the number of cellular users has increased,
many new subscribers are low users. In the United Kingdom cable
operators are gaining some 500,000 extra subscribers per month.
Voice Mail
Voice mail allows incoming messages to be recorded for later playback
when the call is not answered. In advanced forms of voice mail the user
may record a message to be sent later in the day.
For residential service voice mail can either be purchased from the
telephone company as an exchange-based service or it is available by
purchasing an answering machine. This usually contains a regular
telephone set along with a recording, playback, and automatic ring
detection capability. If an incoming call is answered at any telephone
on the line before a pre-set number of rings, the answering machine
does nothing. However, after the pre-set number of rings, the answering
machine goes off hook and plays a pre-recorded message stating that the
owner cannot answer the phone now and inviting the caller to leave a
message to be recorded.
The answering machine’s owner is alerted to the
presence of a recorded message by a light or audible “beep” and can
retrieve the message later. Most answering machines and all
exchange-based services also allow the owner to retrieve recorded
messages from a remote location by dialing a code after the machine has
answered.
Bibliography:
• “Meyer, Ralph, Old-Time Telephones! Design,
History, and Restoration, 2nd Edition (now includes AE phones), Atglen,
Pennsylvania: Schiffer Publishing Ltd., 2005”
• “Dooner, Kate, Telephones Antique to Modern, West
Chester, Pennsylvania: Schiffer Publishing, Ltd., 1992”
• “Microsoft Encarta Interactive World Atlas 2008”
• “Wikipedia the free encyclopedia"
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