Telephone
The telephone or phone
(Greek: tele = far away and phone = voice) is a
telecommunications device that transmits speech
by means of electric signals. Generally
attributed to the inventor Alexander Graham
Bell, the first was built in Boston,
Massachusetts, in 1876. However, an Italian
inventor Antonio Meucci is said to have invented
the device in 1849, and in June 2002 Meucci was
officially credited by the US Congress
(Resolution 269) with the invention of the
telephone, instead of Alexander Graham Bell.
According to other sources Philip Reis invented
it in 1860, but due to a false translation of
the German word "Telephon" his invention was
considered only the predecessor of Bell's.
History
The early history of the telephone is
a confusing morass of claim and counterclaim,
which was not clarified by the huge mass of
lawsuits which hoped to resolve the patent
claims of individuals. There was a lot of money
involved, particularly in the Bell Telephone
companies, and the aggressive defense of the
Bell patents resulted in much confusion.
Additionally, the earliest investigators
preferred publication in the popular press and
demonstrating to investors instead of scientific
publication and demonstrating to fellow
scientists.
It is important to note that there is no
"inventor of the telephone." The modern
telephone is the result of work done by many
hands, all worthy of recognition of their
addition to the field.
See Timeline of the telephone for a
chronological survey of the telephone's
invention and development.
See Invention of the telephone for a discussion
of each of the critical technologies and their
inventors.
The text below draws heavily on Heroes of the
Telegraph by John Munro, Project Gutenberg
edition [1] (http://www.gutenberg.net/etext/979).
Non-electric
'telephones'
There is a sense in which a telephone
is any mechanism capable of conduction sound for
a great distance. The very earliest telephones
were mechanical devices based on sound
transportation through air or other physical
media rather than electrical devices depending
on electro-magnetic signals.
According to a letter in the Peking Gazette, in
968, the Chinese inventor Kung-Foo-Whing
invented the thumtsein, which probably
transported the speech through pipes. Speaking
tubes remained common and can still be found
today.
The lover's telephone (or string telephone) has
also been known for centuries, connecting two
diaphragms with string or wire which transmits
the sound from one to the other by vibrations
along the string and not through electric
current. The classic example is the children's
toy made by connecting the bottoms of two paper
cups with string.
Electro-magnetic transmitters
Antonio Meucci
It may be argued that telephone was invented
around 1860 by Antonio Meucci who called it
teletrophone.
From [2] (http://www.italianhistorical.org/MeucciStory.htm)
Despite a public statement by the then Secretary
of State that "there exists sufficient proof to
give priority to Meucci in the invention of the
telephone," and despite the fact that the United
States initiated prosecution for fraud against
Bell's patent, the trial was postponed from year
to year until, at the death of Meucci in 1896,
the case was dropped.
The first American demonstration of Meucci's
invention took place in 1860, and had a
description of it published in New York's
Italian language newspaper. Meucci invented a
paired electro-magnetic transmitter and
receiver, where the motion of a diaphram
modulated a signal in a coil by moving an
electromagnet. This resulted in a good fidelity,
but a very weak signal. Meucci is also credited
with the early invention of the anti-sidetone
circuit, and of inductive loading of telephone
wires to increase long-distance signals.
Unfortunately, serious burns, lack of English
and poor business abilities resulted in Meucci
failing to develop his inventions commercially
in America. Meucci demonstrated some sort of
instrument in 1849 in Havana, Cuba, but the
evidence is unclear if this was an electric
telephone or a variant on the string telephone
using wires.
Meucci was recognised as the first inventor of
the telephone by the United States Congress, in
its resolution 269 dated 11 June 2002.
Charles Bourseul
In 1854 in the magazine "L'Illustration de
Paris" M. Charles Bourseul, a French
telegraphist, published a plan for conveying
sounds and even speech by electricity. Suppose,'
he explained, 'that a man speaks near a movable
disc sufficiently flexible to lose none of the
vibrations of the voice; that this disc
alternately makes and breaks the currents from a
battery: you may have at a distance another disc
which will simultaneously execute the same
vibrations.... It is certain that, in a more or
less distant future, speech will be transmitted
by electricity. I have made experiments in this
direction; they are delicate and demand time and
patience, but the approximations obtained
promise a favourable result.'
Johann Philipp Reis
In 1860 Johann Philipp Reis produced a
device which could transmit musical notes, and
even a lisping word or two. The Reis transmitter
was a make-break transmitter. That is, a needle
attached to a diaphram was alternately pressed
against, and released from a contact as the
sound moved the diaphram. This make-or-break
signaling was able to transmit tones, and some
vowels, but since it did not follow the analog
shape of the sound wave (the contact was pure
digital, on or off) it could not transmit
consonants, or complex sounds. The Reis
transmitter was very difficult to operate, since
the relative position of the needle and the
contact were critical to the device's operation
at all. This can be called a "telephone", since
it did transmit sounds over distance, but is
hardly a telephone in the modern sense, as it
failed to transmit a good copy of any supplied
sound. Reis' invention is best known then as the
"musical telephone".
Cromwell Varley
Around 1870 Mr. Cromwell Fleetwood Varley,
F.R.S., a well-known English electrician,
patented a number of variations on the audio
telegraph based on Reis' work. He never claimed
or produced a device capable of transmitting
speech, only pure sounds.
Poul la Cour
Around 1874 Poul la Cour, a Danish inventor,
experimented with audio telegraphs on a line of
telegraph between Copenhagen and Fredericia in
Jutland. In this a vibrating tuning-fork
interrupted the current, which, after traversing
the line, passed through an electromagnet, and
attracted the limbs of another fork, making it
strike a note like the transmitting fork.
Moreover, the hums were made to record
themselves on paper by turning the
electromagnetic receiver into a relay, which
actuated a Morse code printer by means of a
local battery. Again, la Cour made no claims of
transmitting voice, only pure tones.
Elisha Gray
Mr. Elisha Gray, of Chicago also devised a
tone telegraph of this kind about the same time
as Herr La Cour. In this apparatus a vibrating
steel reed interrupted the current, which at the
other end of the line passed through an
electromagnet and vibrated a matching steel reed
near its poles. Gray's 'harmonic telegraph,'
with the vibrating reeds, was used by the
Western Union Telegraph Company. Since more than
one set of vibrations — that is to say, more
than one note — can be sent over the same wire
simultaneously, the harmonic telegraph can be
utilised as a 'multiplex' or many-ply telegraph,
conveying several messages through the same wire
at once; and these can either be read by the
operator by the sound, or a permanent record can
be made by the marks drawn on a ribbon of
travelling paper by a Morse recorder.
Gray's harmonic telegraph apparatus follows in
the track of Reis and Bourseul — that is to say,
the interruption of the current by a vibrating
contact. Gray recognized the lack of fidelity of
the make-break transmitter, and reasoned by
analogy with the lovers telegraph that if the
current could be made to model more closely the
movements of the diaphram rather than simply
turning the circuit on and off, a greater
fidelity might be achieved. Gray built and
patented a liquid microphone, where a needle was
placed just barely in contact with a liquid
conductor, and as the diaphram vibrated, the
needle dipped more-or-less into the liquid,
resulting in more-or-less current passing to the
receiver. Bell used a Gray liquid transmitter
for many of his early public demonstrations. The
liquid transmitter had the problem that the
waves formed on the surface of the liquid
resulted in interference.
Carbon Grain
transmitter
Thomas Edison
Thomas Alva Edison took the next step in
developing telephonic fidelity with his
invention of the carbon grain transmitter.
Edison discovered that carbon grains, squeezed
between two metal plates had a resistance that
was related to the pressure, thus, the grains
could vary their resistance as the plates moved
in response to sound waves, and reproduce sound
with good fidelity, without the problems
associated with a liquid contact. This style of
transmitter remained standard in telephony until
the 1980s, and is still produced.
Bell's
invention and claims
Alexander Graham Bell is commonly,
but incorrectly (see Antonio Meucci), credited
as the inventor of the telephone. The classic
story of his crying out "Watson, come here! I
need you!" is a part of the common western
mythos.
Bell's background
As Professor of Vocal Physiology in the
University of Boston, Bell was engaged in
training teachers in the art of instructing deaf
mutes how to speak, and experimented with the
Leon Scott phonautograph in recording the
vibrations of speech. This apparatus consists
essentially of a thin membrane vibrated by the
voice and carrying a light stylus, which traces
an undulatory line on a plate of smoked glass.
The line is a graphic representation of the
vibrations of the membrane and the waves of
sound in the air.
This background prepared him for work with sound
and electricity. He began his researches in 1874
with a musical telegraph, in which he employed a
make-break circuit driven by a vibrating iron
reed which created interrupted current to
vibrate the receiver, which consisted of an
electro-magnet causing an iron reed or tongue to
vibrate, exactly the same as Bourseul, Reis and
Gray. One day it was found that a reed failed to
respond to the intermittent current. Mr. Bell
desired his assistant, who was at the other end
of the line, to pluck the reed, thinking it had
stuck to the pole of the magnet. Mr. Watson
complied, and to his astonishment Bell observed
that the corresponding reed at his end of the
line there upon began to vibrate and emit the
same note, although there was no interrupted
current to make it. A few experiments soon
showed that his reed had been set in vibration
by the magneto-electric currents induced in the
line by the mere motion of the distant reed in
the neighbourhood of its magnet. This discovery
led him to discard the battery current
altogether and rely upon the magneto-induction
currents of the reeds themselves. Moreover, it
occurred to him that, since the circuit was
never broken, all the complex vibrations of
speech might be converted into sympathetic
currents, which in turn would reproduce the
speech at a distance.
Bell, with his assistant Watson discovered that
the movements of the reed alone in a magnetic
field could transmit the modulations of the
sound. Working from the analogy of the
phonautograph, Bell devised a receiver,
consisting of a stretched diaphragm or drum of
goldbeater's skin with an armature of magnetised
iron attached to its middle, and free to vibrate
in front of the pole of an electromagnet in
circuit with the line.
Bell's success
Alexander Graham Bell's
telephone patent drawing, 03/07/1876.
This apparatus was completed
on June 2, 1875, and the same day he succeeded
in transmitting sounds and audible signals by
magneto-electric currents and without the aid of
a battery. On July 1, 1875, he instructed his
assistant to make a second membrane-receiver
which could be used with the first, and a few
days later they were tried together, one at each
end of the line, which ran from a room in the
inventor's house at Boston to the cellar
underneath. Bell, in the room, held one
instrument in his hands, while Watson in the
cellar listened at the other. The inventor spoke
into his instrument, 'Do you understand what I
say?' and we can imagine his delight when Mr.
Watson rushed into the room, under the influence
of his excitement, and answered, 'Yes.' However,
the first successful bi-directional telephone
call by Bell wasn't made until March 10, 1876
when Bell spoke into his device, "Mr. Watson,
come here, I want to see you." and Watson
answered. Thus, by 1875, Bell had re-invented
Meucci's electro-magnetic sound powered
transmitter. The first long distance telephone
call was made on August 10, 1876 by Bell from
the family homestead in Brantford, Ontario to
his assistant located in Paris, Ontario, some 16
km (10 mi.) distant.
A finished instrument was then made, having a
transmitter formed of a double electromagnet, in
front of which a membrane, stretched on a ring,
carried an oblong piece of soft iron cemented to
its middle. A mouthpiece before the diaphragm
directed the sounds upon it, and as it vibrated
with them, the soft iron 'armature' induced
corresponding currents in the cells of the
electromagnet. These currents after traversing
the line were passed through the receiver, which
consisted of a tubular electromagnet, having one
end partially closed by a thin circular disc of
soft iron fixed at one point to the end of the
tube. This receiver bore a resemblance to a
cylindrical metal box with thick sides, having a
thin iron lid fastened to its mouth by a single
screw. When the undulatory current passed
through the coil of this magnet, the disc, or
armature-lid, was put into vibration and the
sounds evolved from it.
The primitive telephone was rapidly improved,
the double electromagnet being replaced by a
single bar magnet having a small coil or bobbin
of fine wire surrounding one pole, in front of
which a thin disc of ferrotype is fixed in a
circular mouthpiece, and serves as a combined
membrane and armature. On speaking into the
mouthpiece, the iron diaphragm vibrates with the
voice in the magnetic field of the pole, and
thereby excites the undulatory currents in the
coil, which, after travelling through the wire
to the distant place, are received in an
identical apparatus. [This form was patented
January 30, 1877.] In traversing the coil of the
latter they reinforce or weaken the magnetism of
the pole, and thus make the disc armature
vibrate so as to give out a mimesis of the
original voice. The sounds are small and elfin,
a minim of speech, and only to be heard when the
ear is close to the mouthpiece, but they are
remarkably distinct, and, in spite of a
disguising twang, due to the fundamental note of
the disc itself, it is easy to recognise the
speaker.
Public
demonstrations
Earliest public of Bell's telephone
The apparatus was exhibited at the Centennial
Exhibition, Philadelphia, in 1876, where it
attracted the attention of Brazilian emperor
Pedro II, and at the meeting of the British
Association in Glasgow, during the autumn of
that year, Sir William Thomson revealed its
existence to the European public. In describing
his visit to the Exhibition, he went on to say:
'In the Canadian department I heard, "To be or
not to be . . . there's the rub," through an
electric wire; but, scorning monosyllables, the
electric articulation rose to higher flights,
and gave me passages taken at random from the
New York newspapers: "s.s. Cox has arrived" (I
failed to make out the s.s. Cox); "The City of
New York," "Senator Morton," "The Senate has
resolved to print a thousand extra copies," "The
Americans in London have resolved to celebrate
the coming Fourth of July!" All this my own ears
heard spoken to me with unmistakable
distinctness by the then circular disc armature
of just such another little electro-magnet as
this I hold in my hand.'
To hear the immortal words of Shakespeare
uttered by the small inanimate voice which had
been given to the world must indeed have been a
rare delight to the ardent soul of the great
electrician.
The surprise created among the public at large
by this unexpected communication will be readily
remembered. Except one or two inventors, nobody
had ever dreamed of a telegraph that could
actually speak, any more than they had ever
fancied one that could see or feel; and
imagination grew busy in picturing the outcome
of it. Since it was practically equivalent to a
limitless extension of the vocal powers, the
ingenious journalist soon conjured up an
infinity of uses for the telephone, and hailed
the approaching time when ocean-parted friends
would be able to whisper to one another under
the roaring billows of the Atlantic. Curiosity,
however, was not fully satisfied until Professor
Bell, the inventor of the instrument, himself
showed it to British audiences, and received the
enthusiastic applause of his admiring
countrymen.
Later public demonstrations
The later form based on Gray's liquid
transmitter was publicly exhibited on May 4,
1877 at a lecture given by Professor Bell in the
Boston Music Hall. 'Going to the small telephone
box with its slender wire attachments,' says a
report, 'Mr. Bell coolly asked, as though
addressing some one in an adjoining room, "Mr.
Watson, are you ready!" Mr. Watson, five miles
away in Somerville, promptly answered in the
affirmative, and soon was heard a voice singing
"America." [...] Going to another instrument,
connected by wire with Providence, forty-three
miles distant, Mr. Bell listened a moment, and
said, "Signor Brignolli, who is assisting at a
concert in Providence Music Hall, will now sing
for us." In a moment the cadence of the tenor's
voice rose and fell, the sound being faint,
sometimes lost, and then again audible. Later, a
cornet solo played in Somerville was very
distinctly heard. Still later, a three-part song
floated over the wire from the Somerville
terminus, and Mr. Bell amused his audience
exceedingly by exclaiming, "I will switch off
the song from one part of the room to another,
so that all can hear." At a subsequent lecture
in Salem, Massachusetts, communication was
established with Boston, eighteen miles distant,
and Mr. Watson at the latter place sang "Auld
Lang Syne," "The Star-Spangled Banner", and
"Hail Columbia," while the audience at Salem
joined in the chorus.'
Summary of
Bell's achievements
Bell adopted Gray's, and later Edison's
resistive transmitters and adapted switching
plug boards developed for telegraphy by Western
Union. It would be inappropriate to minimize
Bell's contribution to the development of
telephony. Additionally, Bell succeeded where
others failed to assemble a commercially viable
telephone system. It can be argued that Bell
invented the telephone company.
Later
developments
Bell had overcome the difficulty which baffled
Reis, and succeeded in making the undulations of
the current fit the vibrations of the voice as a
glove will fit the hand. But the articulation,
though distinct, was feeble, and it remained for
Edison, by inventing the carbon transmitter, and
Hughes, by discovering the microphone, to render
the telephone the useful and widespread
apparatus which we see it now.
Misc
The Ericofon was a very futuristic handset when
it was introduced in 1956.The modern handset
came into existence when a Swedish lineman tied
a microphone and earphone to a stick so he could
keep a hand free. The folding portable phone was
an intentional copy of the fictional futuristic
communicators used in the television show Star
Trek.
The history of additional inventions and
improvements of the electrical telephone
includes the carbon microphone (later replaced
by the electret microphone now used in almost
all telephone transmitters), the manual
switchboard, the rotary dial, the automatic
telephone exchange, the computerized telephone
switch, Touch Tone® dialing (DTMF), and the
digitization of sound using different coding
techniques including pulse code modulation or
PCM (which is also used for .WAV files and
compact discs).
Newer systems include IP telephony, ISDN, DSL,
cell phone (mobile) systems, digital cell phone
systems, cordless telephones, and the third
generation cell phone systems that promise to
allow high-speed packet data transfer.
The industry divided into telephone equipment
manufacturers and telephone network operators (telcos).
Operating companies often hold a national
monopoly. In the United States, the Bell System
was vertically integrated. It fully or partially
owned the telephone companies that provided
service to about 80% of the telephones in the
country and also owned Western Electric, which
manufactured or purchased virtually all the
equipment and supplies used by the local
telephone companies. The Bell System divested
itself of the local telephone companies in 1984
in order to settle an antitrust suit brought
against it by the United States Department of
Justice.
The first transatlantic telephone call was
between New York City and London and occurred on
January 7, 1927.
Fixed Cordless
telephones
Cordless handsetCordless telephones consist of a
base unit that connects to the land-line system
and also communicates with remote handsets by
low power radio. This permits use of the handset
from any location within range of the base.
Because of the power required to transmit to the
handset, the base station is powered with an AC
adapter. Thus, cordless phones typically do not
function during power outages. Initially,
cordless phones used the 1.7 MHz range to
communicate between base and handset. Because of
quality and range problems, these units were
soon superseded by systems that used frequency
modulation in higher frequency ranges (49 MHz,
900 MHz, 2.4 GHz, and 5.8 GHz). 2.4 GHz cordless
phones can interfere with certain wireless LAN
protocols (802.11b/g) due to the usage of the
same frequencies. Due to crowding on the 2.4 GHz
band, several "channels" are utilized in an
attempt to guard against degradation in the
quality of the voice signal. The range of modern
cordless phones is normally on the order of a
few hundred yards.
Wireless phone
systems
They are the satellite and mobile
systems.
Nikola Tesla
On the opening of the telephone exchange in
Budapest, 1881, Nikola Tesla became the chief
electrician to the telephone company (engineer
to the Yugoslavian government and the country's
first telephone system). There Tesla invented a
device he called a telephone repeater or
amplifier. The device could act as a loud
speaker. The invention was never patented nor
released publicly. It was eventually used to
detect signals in wireless transmission
experiments. The apparatus developed in these
experiments were precursors to the modern
wireless telephone.
The apparatus also involved the following:
Antennas (aerial wire)
Ground connections
Antenna-ground circuits containing inductance
and capacity (RLC circuit)
Adjustable inductors and capacitors (for tuning)
Sending and receiving sets tuned to resonance
with each other
Mobile phone
Modern mobile phone systems are
cell-structured. Radio is used to communicate
between a handset and a cell-site. Communication
between cell-sites and the public switched
telephone network can be by digital microwave
radio, digital optic fiber or digital copper
land lines communicating with a telephone
exchange.
When a handset gets too far from a cell-site, a
computer system commands the handset and a
closer cell-site to take up the communications
on a different channel without interrupting the
call.
Modern mobile phones use cells because radio
frequencies are a limited, shared resource.
Cell-sites and handsets have low power
transmitters so that a limited number of radio
frequencies can be reused by many callers with
less interference. An incidental benefit is that
the batteries in the handsets need less power.
Standards
There are many standards for common
carrier wireless telephony, often with
incompatible standards used in the same nation:
First generation - Analog
marine and mobile radio telephony
AMPS
CDPD data service on AMPS
NMT
Satellite systems- digital
Inmarsat
Iridium (satellite)
Second generation (2G) - Digital
CDMA IS-95A
GSM, (different frequencies for different
continents: see GSM article)
iDEN
TDMA IS-136
2.5G
CDMA IS-95B
GPRS
EDGE
PDC-P
Third generation (3G)
CDMA 2000
UMTS, also called W-CDMA
TD-SCDMA
Telephone
equipment manufacturers
Several manufacturers build
telephones of all kinds. Some of these are:
Alcatel
Ericsson
Huawei
Lucent
Marconi
Motorola
Nokia
Nortel
palmOne / Handspring
Samsung
Siemens AG
Sony Ericsson
Telephone
equipment research labs
Bell Labs is a noted telephone
equipment research laboratory, amongst its other
research fields.
Telephone
operating companies
In some countries, many telephone
operating companies (commonly abbreviated to
telco) are in competition to provide telephony
services. Some of them include those in the
following list. However, the list only includes
providers of copper wires from the exchange to
the user, not those who only supply "Voice over
IP" or only transport voice signals between
exchanges.
References
Huurdeman, Anton A. (2003).
The Worldwide History of Telecommunications,
IEEE Press and J. Wiley & Sons, 2003
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