history of telecommunication from telegraph to telephone

8/19/2019 history of telecommunication from telegraph to telephone

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OPTICAL TELEGRAPH

Early Forms of Long Distance Communication

Mankind has attempted to transmit long distance

communication since the advent o its technolog!"

Earlier telecommunications protot!pes resem#led

modern technological developments" In act$ the earliest

orms %ere the greatest achievements or the pioneers

o the time" &ome o the earliest orms o long distancecommunication included smoke signals$ %hich %ere

transmitted via signal to%ers across the %orld" &moke

signal to%ers used polished glass mirrors to rela!

messages along a chain o to%ers positioned in

strategical places" This orm o communication %as the

precursor to the light s!stem used during the

Revolutionar! 'ar" In a matter o decades$ people

across the glo#e kne% %hat these coded messages

meant" (or instance$ )one i #! land$ t%o i #! sea$*

#ecame a nota#le message across a distance" People

also used carrier pigeons to deliver messages across

long distances" The simplicit! o these communication

methods allo%ed or the development o sophisticated

tools used in modern telecommunication"

Centuries o slo% long+distance communications came

to an end %ith the arrival o the telegraph" Most histor!


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#ooks start this chapter %ith the appearance o the

electrical telegraph$ mid%a! the nineteenth centur!"

Ho%ever$ the! skip an important intermediate step" (it!

!ears earlier ,in -./-0 the (renchman Claude Chappe

developed the optical telegraph" Thanks to this

technolog!$ messages could #e transerred ver! 1uickl!

over long distances$ %ithout the need or postmen$

horses$ %ires or electricit!"

I2TRO34CTIO25

6 A#out Optical telegraph"

6 A#out morse telegraph"

6 Ho% the invention o #atter! and electromagnetism

changed the %orld"6 This led the initial developments o telegraph"

HI&TOR75

6 8er! irst drums and ire #eacons %ere used in

order to transer the inormation"

6 This is earl! kind o communication"

6 Later animals are used or an inormation carrier

such as horses$pigeons"

6 Later$optical telegraphs %ere invented until then

horses are the high speed carriers"

CHAI2 O( TO'ER&5


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The optical telegraph net%ork consisted o a chain o

to%ers$ each placed 9 to :; kilometres apart rom each

other" On each o these to%ers a %ooden semaphore

and t%o telescopes %ere mounted ,the telescope %as

invented in -t he used the telescope to look at the succeeding

to%er in the chain$ to control i the ne>t telegrapher hadcopied the s!m#ol correctl!" In this %a!$ messages %ere

signed through s!m#ol #! s!m#ol rom to%er to to%er"

The semaphore %as operated #! t%o levers" A

telegrapher could reach a speed o - to ? s!m#ols per

minute"


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(42CTIO2I2G5

6 Claude and chappe invented the optical telegraph

%hich %as also kno%n as mechanical telegraph"

6 This consists o : arms and a shat"

6 'here shat is kno%n as regulator and arms are

kno%n as indicators"

6 Later improvements increased the arms num#er to


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6 This does not re1uire an! electrical signals as input

#ut the operation is mainl! #! movement o lever

%hich is connected to arms and shat"

6 The signals that are send are received #! o#serving

through telescope"

6 These are mounted on top o to%ers"so that the!

can provide #est line o sight"

I2&I3E A23 O4T&I3E O( (RA2CE5

6 8er! irst line %as #uilt in rance #et%een paris and

lille"

6 In #et%een these : there %ere -9 stations"

6 Each station can receive ? letters in ?


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6 It is e>pensive,no o stations0"

6 It re1uires man po%er"

6 It re1uires line o sight"

6 'hether conditions should #e considered$%e canBt

see in dark"

CO2CL4&IO25

6 Here$i e>plained a#out histor! o telegraphs"

6 Mainl! optical telegraphs %hich gives an idea to the

electrical telegraphs to have lines and to use TD

and RD"

6 Also due to coding i"e #! using certain codes %e

have developed the semaphore"

6 This gave an idea to morse to develop morse code"

6 &o i conclude #! sa!ing that optical telegraph

provides root strength to communication"


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This igure indicates shat and regulator o optical

telegrap$ consists o : arms"

3eveloped version o optical telegarph consisted o <

arms to send more inormation"The optical telegraph

net%ork %as solel! used or militar! and national

communications$ individuals did not have access to it

although it %as used or transmitting %inning lotter!num#ers and stock market data"

The optical telegraph disappeared as ast as it came"

This happened %ith the arrival o the electrical telegraph$

it! !ears later" The last optical line in (rance %as

stopped in -F9?$ in &%eden the technolog! %as used up

to -FF;" The electrical telegraph %as not hindered #!


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mist$ %ind$ heav! rainall or lo% hanging clouds$ and it

could also #e used at night"

ELECTRICAL TELEGRAPH

The telegraph %as the irst rom o communication

that could #e sent rom a great distance and %as a

landmark in human histor!" (or the irst time man could

communicate %ith another rom a great distance

changing ever!thing rom ho% %ars %ere ought to ho%people dated and ell in love" ItBs creation$ along %ith the

steam engine$ %as one o the ke! inventions to the

industrial age" Letters took hours$ da!$ and even months

to arrive at their destination making most inormation

irrelevant" Ho%ever$ %ith the advent o the telegraph$


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messages %ere transmitted instantaneousl!$ and as it

#ecame ever more eicient the telegraph %as a#le to

rela! more comple> messages arther and arther till it

connected people rom around the %orld #! pressing a

e% #uttons"

3eveloped in the -F?;s and -F=;s #! Samuel Morse

,-./-+-F.:0 and other inventors$ the telegraph

revolutionied long+distance communication" It %orked

#! transmitting electrical signals over a %ire laid

#et%een stations"

The irst telegram in the 4nited &tates %as sent #!

Morse on 11 January 1838$ across t%o miles ,? km0 o

%ire at &peed%ell Iron%orks near Morristo%n$ 2e%erse!$ although it %as onl! later$ in 18$ that he sent

the message 'HAT HATH GO3 'RO4GHT rom the

Capitol in 'ashington to the old Mt" Clare 3epot in

@altimore"

Ater the invention o optical telegraph several

developments took place in the communication

ield"chemical telegraph #! using electrol!sis

process$electro magnetic telegraph i"e #! using

magnetic needles several developments %ere made"@ut

it %as the morse telegraph %hich had changed the


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%orld"It %as the ver! irst international communication

s!stem"

The mechanism o electrical telegraph re1uires not more

than a ke!$#atter!$ca#les$paper$line o poles #%

transmission and reception"%hen press the ke!$circuit is

closed and the %ire is connected to #atter! and negative

is grounded"%hen ke! is closed current is passed

through the %ire to the coil connected to a rod %hich is

electro+magnetic and that attracts the armature"%here

the other end o armature is having a spring"The

armature on the coil side is having a marker pointing on

a paper,dots and dashes0"

'here the received signals on the paper are in the orm

o dots and dashes"This is kno%n as morse code"Eachletter and alpha#et is indicated %ith com#ination o dots

and dashes"And here signal is to #e listened %hen it

makes sound and moreover itBs is hard to understand

and produce it astl!"

This morse code is even used in da! to da! modern

lie"ItBs used %hen there is no availa#ilit! o modern

communication due to #ad climatic conditions"Hams

radio is used to communicate at that situations %here it

onl! re1uires a #atter! and morse code to code"%here it

is 9; times more aster than the modern voice message


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communication"This is useul or soldiers at their remote

%ork places to send the signals"It is used in arm! to

communicate or to send private inormation

%isel!"Ho%ever it had changed and #ought the %orld a

head #ut signal sensing comple>it! is more and %ith the

ne% developments it had #een let a side"

The electric telegraph transormed ho% %ars %ere

ought and %on and ho% Journalists and ne%spapers

conducted #usiness" Rather than taking %eeks to #e

delivered #! horse+and+carriage mail carts$ pieces o

ne%s could #e e>changed #et%een telegraph stations

almost instantl!" The telegraph also had a proound

economic eect$ allo%ing mone! to #e )%ired* across

great distances"


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TELEPHO2E Ale>ander Graham @ell ,-F=.+-/::0$ the &cottish+#orn

American scientist #est kno%n as the inventor o the

telephone$ %orked at a school or the dea %hile

attempting to invent a machine that %ould transmitsound #! electricit!" @ell %as granted the irst oicial

patent or his telephone in March -F.


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rest o his lie$ and used his success and %ealth to

esta#lish various research centers nation%ide"

@ell o%es his immortalit! to his having #een the irst to

design and patent a practical device or transmitting the

human voice #! means o an electric current" @ut @ell

al%a!s descri#ed himsel simpl! as a )teacher o the

dea$* and his contri#utions in that ield %ere o the irst

order"

@ell$ %ho %as #orn in Edin#urgh$ &cotland$ %as

educated there and at the 4niversit! o London" He also

studied under his grandather$ Ale>ander @ell$ a noted

speech teacher" He taught elocution$ assisted his ather$

also a speech teacher and noted phonetician$ and

taught at a school or the dea in England$ using hisatherBs methods" In -F.;$ @ell immigrated %ith his

parents to Canada"

T%o !ears later he esta#lished a school or the dea in

@oston$ Massachusetts$ and the ollo%ing !ear #ecame

a proessor in speech and vocal ph!siolog! at @oston

4niversit!" 'hile teaching he e>perimented %ith a

means o transmitting several telegraph messages

simultaneousl! over a single %ire and also %ith various

devices to help the dea learn to speak$ including a

means o graphicall! recording sound %aves"

http://www.history.com/topics/us-states/massachusettshttp://www.history.com/topics/us-states/massachusetts


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In -F.= the essential idea o the telephone ormed

in his mind" As he later e>plained it$ )I I could make a

current o electricit! var! in intensit! precisel! as the air

varies in densit! during the production o sound$ I should

#e a#le to transmit speech telegraphicall!"* T%o !ears

later he applied or a patent$ %hich %as granted on

March .$ -F.


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TELEPHO2E PART&56 HA23&ET

6 MO4THPIECE

6 MICROPHO2E

6 LO43&PEAER

LetNs think a#out a t!pical phone handset" At the top$

thereNs a loudspeaker !ou press against !our ear" At the

#ottom$ thereNs a microphone !ou put near !our mouth"

Coming out o the handset$ %rapped inside a single

thick$ coiled ca#le$ are t%o pairs o copper %ires" One

pair is an output5 it takes outgoing electrical signals rom

the microphone to the telephone s!stem the other pair

is an input5 it takes incoming signals rom the telephone

s!stem to the loudspeaker"The loudspeaker and

microphone %ork in similar #ut opposite %a!s" The

http://www.explainthatstuff.com/microphones.htmlhttp://www.explainthatstuff.com/microphones.html


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microphone contains a le>i#le piece o plastic called a

diaphragm %ith an iron coil attached to it and a magnet

near#!" 'hen !ou speak into the mouthpiece$ the sound

energ! in !our voice makes the diaphragm vi#rate$

moving the coil nearer to or urther rom the magnet"

This generates an electric current in the coil that

corresponds to the sound o !our voice5 i !ou talk loud$

a #ig current is generated i !ou talk sotl!$ the current is

smaller" 7ou can think o a microphone as an energ!

converting device5 it turns the sound energ! in !ourvoice into electrical energ!" &omething that converts

energ! rom one orm to another is called a transducer"

The loudspeaker in a phone %orks in the opposite %a!5

it takes an incoming electrical current and uses

magnetism to convert the electrical energ! #ack into

sound energ! !ou can hear" In some phones$ theloudspeaker and microphone units are virtuall! identical$

Just %ired up in opposite %a!s"

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!o" lou#s$eakers turn electricity into soun#

'hen things shake a#out$ or vi#rate$ the! make the

sounds %e can hear in the %orld around us" &ound is

invisi#le most o the time$ #ut sometimes !ou can

actuall! see it I !ou thump a kettle+drum %ith a stick$

!ou can see the tight drum skin moving up and do%nver! 1uickl! or some time ater%ardKpumping sound

%aves into the air" Loudspeakers %ork in a similar %a!"

At the ront o a loudspeaker$ there is a a#ric$ plastic$

paper $ or light%eight metal cone ,sometimes called a

#ia$hragm0 not unlike a drum skin ,colored gra! in our

picture0" The outer part o the cone is astened to the

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outer part o the loudspeakerNs circular metal rim" The

inner part is i>ed to an iron coil ,sometimes called the

%oice coil$ colored orange in the diagram0 that sits Just

in ront o a permanent magnet ,sometimes called the

fiel# magnet$ and colored !ello%0" 'hen !ou hook up

the loudspeaker to a stereo$ electrical signals eed

through the speaker ca#les ,red0 into the coil" This turns

the coil into a temporar! magnet or electromagnet" As

the electricit! lo%s #ack and orth in the ca#les$ the

electromagnet either attracts or repels the permanentmagnet" This moves the coil #ack and or%ard$ pulling

and pushing the loudspeaker cone" Like a drum skin

vi#rating #ack and orth$ the moving cone pumps sounds

out into the air"

!o" micro$hones "ork

Ho% does a microphone turn sound energ! intoelectrical energ! Like this5

-" 'hen !ou speak$ soun# "a%es created #! !our

voice carr! energ! to%ard the microphone"

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Remem#er that sound %e can hear is energ!

carried #! vi#rations in the air"

:" Inside the microphone$ the #ia$hragm ,much

smaller than !ouNd ind in a loudspeaker and usuall!

made o ver! thin plastic0 moves #ack and orth

%hen the sound %aves hit it"

?" The coil$ attached to the diaphragm$ moves #ack

and orth as %ell"

=" The $ermanent magnet produces a magnetic ield

that cuts through the coil" As the coil moves #ackand orth through the magnetic ield$ an electric

current lo%s through it"

9" The electric current lo%s out rom the microphone

to an ampliier or sound recording device" He!

presto$ !ouNve converted !our original sound into

electricit! @! using this current to drive soundrecording e1uipment$ !ou can eectivel! store the

sound orever more" Or !ou could ampli! ,#oost the

sie o0 the current and then eed it into a

loudspeaker$ turning the electricit! #ack into much

louder sound" ThatNs ho% PA ,personal address0

s!stems$ electric guitar ampliiers$ and rock concertampliiers %ork"

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converted rom one orm to another and getting #ack our

original voice signal"

ROTAR7 8& 3AIL TO2E E7PA35


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These igures indicates the internal and e>ternal vie% o rotar! ke!pad"

&one Dialing %s 'ulse Dialing

Tone and pulse dialing are t%o %a!s o communicating%ith the central telephone rela! to indicate the telephone

num#er that !ou %ish to call" Pulse dialing indicates

each digit in the phone num#er #! a series o clicks that

corresponds onl! to that digit" It %ould then need a short

pause in order to clearl! identi! one digit rom the ne>t"

Tone dialing$ also called as 3ual Tone Multi (re1uenc!$uses dierent tones to indicate a dierent num#er"

Instead o sending multiple signals or each digit$ it

%ould onl! need to send one or each"

(or most cases$ the most discriminating part #et%een

phone sets that use pulse or tone dialing is the

mechanism used to dial the num#er" Tone dialing

handsets use a numeric ke!pad %here !ou simpl! push

each digit" Although there are some versions o pulse

dialing phones %ith numeric ke!pads$ the most

prevalent models %ere those e1uipped %ith rotar! dials"

This dierence #et%een the t%o has huge implications

%ith the ease o use" 3ialing a num#er %ith a rotar! dial

takes a lot longer since !ou %ould need to %ait or thedial to return in its resting position #eore !ou can dial

the ne>t digit" This is not an issue %ith tone dialing

phones !ou can dial as 1uickl! as !ou can or %ant

%ithout causing an! pro#lem"

3ue to the advantages o tone dialing$ it has no%

#ecome the standard or telephone companies all over

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the %orld" 7ou %ould #e hard pressed to ind an area

that still uses pulse dialing" 3espite this$ most telephone

s!stems that uses tone dialing are also a#le to

recognie and %ork %ith pulse dialing" &ome handsetsare also manuactured to support #oth pulse and tone

dialing"

The 3TM( telephone ke!pad is laid out in a =Q= matri>

o push #uttons in %hich each ro% represents the low

re1uenc! component and each column represents thehigh re1uenc! component o the 3TM( signal" Pressing

a ke! sends a com#ination o the ro% and column

re1uencies"


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history of telecommunication from telegraph to telephone

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