Telephony Part 1 Rev

TELEPHONY

ENGR.PHI L LOM OMB BOY

TELEPHONY t heartofpr oj ect i ngas oundwave i nt oagi venappar at us ,t r ans f or m i ng mi t hes oundwavei nt oanel ect ri cal wave,pas s i ngt heel ect ri calwaveover awi r eorci r cui tandt hen t r ans f ormi mi ngt heel ect ri calwaveback i nt oas oundwave. 

TELEPHONY t heartofpr oj ect i ngas oundwave i nt oagi venappar at us ,t r ans f or m i ng mi t hes oundwavei nt oanel ect ri cal wave,pas s i ngt heel ect ri calwaveover awi r eorci r cui tandt hen t r ans f ormi mi ngt heel ect ri calwaveback i nt oas oundwave. 

THREE MAJOR FUNDAME MENTALS 

PHYSI CAL

HUM UMA AN ELEMENT 

MECHA HANI NI CAL

 APPARATUSOREQUI PMENT 

ELECTRI RI CAL ELECTRI CI TY

GENERAL FUN CTI ONALPARTS UNC 

EXCHANGE NGEPART

GENERAL FUN CTI ONALPARTS UNC 

SUBSCRI BER PART

GENERAL FUN CTI ONALPARTS UNC 

I NTER -EXCHANGE PART

MAI N FUNCTI ONSOFTELEPHONE SET

Toc al lt heLo c alEx c hang e T ot r ans mi tt hede s i r e d s ubs c r i be r ’ s numbe r T or e c e i v edi ffe r e ntt o nes i gnal s T ot r ans mi tandr e c e i v es pe e c h t oo r de rt hec l e ar i ngo fc o nne c t i o n 

MODERN COMPONENTSOFA TELEPHONE SET 1 .Tr ans mi t t e r( mo ut hpi e c e )–c o nv e r t st hes o und wa v ei nt oe l e c t r i c a lwa v e.

2.Re c e i v er( e arpi e c e )–c o nv er t st hevar y i ng e l e c t r i cc ur r e ntt hatr e pr e s e nt st he t r ans mi t t e ds pe e c hs i gnali nt oanaudi bl e s o undt hatwi l lr e c r e at et hes o und.

MODERN COMPONENTSOFA TELEPHONE SET

3.Ri ng e r( be l l )-as i gnal i ngs ys t e mf r o ma t e l e pho nee x c hang et oac al l e dpho net oi mpar t t hatac al ls ho ul dbeans we r e d.

MODERN COMPONENTSOF A TELEPHONE SET br i dFunc t i o n( s pe e c ht r ans f o r me r )–an 4.Hy

i ndi c at i o nc o i lwhi c hi samul t i pl ewi ndi ng t r ans f o r me ri nt e nde dt oi nt e r f ac ea2wi r e c i r c ui tt oa4wi r ec i r c ui tt ope r mi t2wa y t r ans mi s s i o no fs i gnal s ,t hati s ,i nbo t h di r e c t i o natt hes amet i me .

MODERN COMPONENTSOF A TELEPHONE SET 5 .Ba l a nc i ngNe t wo r k–s ma l la mo unto ft he t r ans mi t t e ds i gnali sal s of e dt ot her e c e i v e ro f t het al ki ngpho ne .Suc hs i gnali sc al l e dt he sus e df o raut o mat i c  s i d e t o n e . V a r i s t o ri adj us t me nto ft hes i de t o nel e v e lf o rt e l e pho ne s e t .

MODERN COMPONENTSOFA TELEPHONE SET 6.Ov e r Vo l t ageandRe v e r s ePo l ar i t yPr o t e c t i o n– Ze ne rdi o dei sus e dt opr o t e c tt hec i r c ui t sf r o m t r ans i e nt sando v e r v o l t age s .Re c t i fie rBr i dg e i st heme t ho dc o mmo nl yus e dt opr o t e c t agai ns tpo l ar i t yr e v e r s al . 7. Transmission regulation circuit – together with the speech transformer, it regulates the strength and quality of sound.

MODERN COMPONENTSOF A TELEPHONE SET 8.Di als y s t e m /Pus hbut t o nke y pad Ro t ar yDi al( Pul s eDi al i ng )i smar ke df r o m 0t o 9 wi t h e a c h numb e r r e p r e s e nt i ng a c o r r e s po ndi ngnumb e ro fpul s e st ha two ul db e g e ne r a t e do nc et hedi ali sr o t at e df r o m as t ar t i ng po s i t i o nt o war dst hefix e dpo i nt .

MODERN COMPONENTSOF A TELEPHONE SET Ke ypa dSy s t e m ( DTMF;DualTo neMul t iFr e que nc y) ut i l i z e ss pe c i ficpai r so ff r e que nc ywi t hi nt he v o i c ebandf o re ac hke y .Pr e s s i ngo neo ft he ke y sc a us e sane l e c t r o ni cc i r c ui tt oge ne r at e t wot o ne si nt hev o i c ef r e que nc yband.The r ei s al o wf r e que nc yt o nef o re ac hc o l umn.

MODERN COMPONENTSOF A TELEPHONE SET Ke ypa dSy s t e m ( DTMF;DualTo neMul t iFr e que nc y)

DTMFVSPULSE DI ALI NG 

DTMFdi al i ngr e c o g ni z e sdi g i tt o ne si n50 ms e c ,wi t hani nt e r di gi ti nt e r valo f ano t he r50ms e c .



Pul s eDi al i ngr e q ui r e s60ms e cbr e a kand 40ms e cmake( t o t alo f100ms e c )f o re ac h di alpul s e .Thei nt e r di gi ti nt e r v ali s700 ms e c .

EXAMPLE 

Ho w muc ht i mewo ul dyo us av ei fyo udi al7811 00 5us i ngDTMFdi al i ngo v e rpul s edi a l i ng ?

GUESSTHETI TLE

SWI TCHI NG NG SYSTEMS 1.ManualCo nt r o l –e ar l yt e l e pho nes wi t c hbo ar dswe r eo pe r at e d manual l yus i ngaj ac kf o re ac hl i nea ndt wopl ug s o nal o ngfle xi bl ewi r e ,c al l e dc o r dpai r ,f o r maki ngt hec o nne c t i o n.

MANUALCONTROL

-t omakec o nne c t i o n,t heo pe r at o rpi c ke dupa c o r d,pl ugg e di ti nt ot hej ac kc o r r e s po ndi ngt ot he l i ner e que s t i ngs e r vi c e ,o bt ai ne df r o mt hec al l i ng par t yt henameo rnumbe ro ft hede s i r e dpar t y , andt he npl ug ge dt heo t he re ndo ft hec o r dpai r i nt ot hec o r r e c to ut go i ngl i nej ac k.

SWI TCHI NG NG SYSTEMS 2.Pr o gr e s s i v eCo nt r o l( St e pb ySt e pSwi t c hi ng ) -ac a l li spr o gr e s s i v e l yc ar r i e do utt ot hede s i r e d t e r mi nalunde rt hedi r e c tc o nt r o lo ft he s ubs c r i be r ’ si ni t i at e dpul s e s . -i nv e nt e dbyAl mo nB.St r o wg e ri n1 889

PROGRESSI VECONTROL

PROGRESSI VECONTROL

SWI TCHI NG NG SYSTEMS 3.Co mmo nCo nt r o l( Cr o s s barSys t e m) -me t ho do fs wi t c hi ngwhi c hwhe ndi r e c t e dt o ac o mmo nc o nt r o luni twi l ls e l e c tandc l o s ea pa t ht hr o ug hama t r i xa r r a ng e me nto f s wi t c he sc al l e dc r o s s baro rc r o s s po i nt s wi t c he s .

SWI TCHI NG NG SYSTEMS 4.St o r e dPr o g r a m Co nt r o l ( El e c t r o ni cSwi t c hi ngSy s t e m;ESS) -t hes wi t c hi ngpr o c e dur e sar ec o nt r o l l e dby me anso fac omput e randpr o gr am s of t war e t hatmo ni t o r sal lo ffic eac t i vi t y ,s e e swhat s e r vi c ene edsar e ,andi ni t i at e sac t i o nt of ul fil l t hene e d

STORED PROGRAM CONTROL St o r e dPr o g r a m Co nt r o l ( El e c t r o ni cSwi t c hi ngSy s t e m;ESS) Fe a t ur e s :

SI GNALI NG 

Re f e r st ot hes pe c i fics i gnal so nt he t r ans mi s s i o nl i net hatar eus e df o rc o nt r o l l i ng t hec o nne c t i o nf r o mt hec al l i ngt e l e pho net o t hec al l e dt e l e pho neands i gnal st hatar eus e d t oi ndi c at et hes t at uso fac alasi ti sbe i ng i nt e r c o nne c t e d.



Pr o v i de same a nsf o ro p e r a t i ngand s upe r v i s i ngat e l e pho nec o mmuni c at i o n s ys t e m.



Es t abl i s he sc o nne c t i o ns ,anno unc e si nc o mi ng c al l sandr e po r t st hef ac tt hatal i nei sb s y . fc ie

SI GNALI NG FUNCTI ONS 1.Ri ngi ngSi gnal s -us e dt oo pe r a t eavi s i bl eo raudi bl eal ar mt o N o t e: al e r ts o me o neo fani nc o mi ngc a l l . Supe r v i s o r ys i g nal sa nd addr e s ss i gnal sar e 2.Supe r v i s o r ySi gnal s a c c o mpl i s he db yme a nso f -us e dt o c o n v e y i n f o r ma t i o nh r e g ar di ng d i r e c t c u r r e n t ( DC ) w i l e s wi t c hb o a r d o n d i t i o n . ( O ho o ko rOffho o k) r i n g i nc g s i g n a l ss b y An C. 3.Addr e s sSi gnal s -c o nv e ydi al i ngo rdi gi t ali nf o r mat i o nwhe ni s ne c e s s ar yt oes t abl i s ht hede s i r e dc o nne c t i o ns .

SI GNALI NG FUNCTI ONS Thr e eMe t ho dso fSubs c r i be rLo o pSi g na l i ng 1 .We t–Dr y 

Si gnal i ngi nf o r mat i o ni si ndi c a t e db y hepr e s e nc e a yt e ( we t )andabs e nc e( dr y ) fabat t e r ya ndgr o und y )o c o n t i o no nt hel i neatt hec al l e de ndo ft het r unk. o ndi

2.Re v e r s eBat t e r y 

Lo o ps i g n i ngi sa c c o mpl i s he db yr e v e r s i ngt he nal po l ar i t yo ft heb at t e r yo nt hel i net oi ndi c a t e b s upe r vi s o r yc o n t i o ns . o ndi

3.Hi gh–Lo w Me t ho d

OnHoo k–hi ghr es i s t anc e OffHoo k–l o wr es i s t anc e

E& M SI GNALI NG 

Empl o y s2l e adst oc o nne c tt hes i gnal i ng e qui pme ntt ot het r unkc i r c ui t .



Ml e a dt r ans mi t sBat t e r yo rgr o unds i g nal st o t hedi s t ante ndo ft hec i r c ui t swhi l ei nc o mi ng s i gnal sar er e c e i v e do nt heEl e adase i t he ra gr o undo ro pe nc o ndi t i o n



E& M bas i c al l ys t andsf orEarandMo ut h

OUTOF GNALI NG OFBAND SI 

Makesus eo foneo rmor eACt oneswhi c hl i e wi t hi nt hepas s bando ft het r ans mi s s i o nf ac i l i t y butj us to ut s i det hev o i c eband.

I N BAND SI GNALI NG 

Si gnal i ngt o ne sa r et r ans mi mi t t e dwi t hi nt he s pe e c hba nd,us ua l l y16 00 ,24 00o r26 00Hz Hz .

COM OMMON CHA HANNELSI GNALI NG SYSTEM   A l ls i gnal i ngf o ranumbe ro fv o i c epat hsi s c ar r i e do v e ro nec o mm mmo nc hanne l ,i ns t e ado f wi t hi ne ac hi ndi v i dualc hanne l .

 ALTERNATE CHANNEL SI GNALI NG Twoc hanne l sa r eus e d,o nec ar r i e st hes i gnal i ng s i gnalwhi l et heo t he rc ar r i e st hev o i c es i gnal .  Ane r r o rde t e c t o rmo ni t o r st hee r r o rr at ei nt he s i gnal i ngc hanne l .I ft heer r o ri st o l e r abl e ,t he s y s t e mi sno r ma mal ;i fmo r et he n3e r r o r so c c urf o r ape r i o do f10s e c o nd,t hel i nes wi t c huni t aut o ma mat i c al l ys wi t c he st hes i gnal i ngc hanne l i nf o r ma mat i o nt ot heal t e r nat ev o i c ec hanne l sa nd t heal t e r nat ec hanne li nf o r ma mat i o nt ot hes i gnal c ha nne l . 

CCI TTSI GNALI NG SYSTEM 1 .Si g na l i ngs y s t e m numb e r1 -I ti sa500/ 20–Hzs y s t e m us e di nt hei nt e r nat i o nal ma nua ls e r v i c e . 2. Si gna l i ngSys t e m Numbe r2 a -I ti sa600/ 7 50Hzs y s t e mt ha thadne v e rb e e n e d e e nus i ni nt e r nat i o nals e r vi c e s . 3. Si gna l i ngSys t e m Numbe r3 a -Us e so nei nbandf r e que nc y ;2280Hz ,uni di r e c t i o nal o pe r at i o no fc i r c ui t s ,f o rt het r ans mi mi s s i o no fbo t hl i ne andi nt e r mi s s i o ns i g nal sus e df o rt e r mi nalt r affic . i

CCI TTSI GNALI NG SYSTEM 4.Signaling System Number 4

- t is used for unidirectional operation of circuits! circuits! to inband frequencies" frequencies" #$4$ and #4$$ %&, for the endto-end transmission of both line and register signals. '. Signaling System Number ' - (oth-way operation of circuits using to inband frequencies! #$4$ and #4$$ %&, for the lin)-by lin) transmission of line signals and si* inband frequencies! 7$$, +$$, $$, $$, '$$, and 7$$ %& in a two-out-of si* code for the transmission of register register signals.

CCI TTSI GNALI NG SYSTEM 6.Si gnal i ngSys t em Number6 -Si gnal i ngl i nkc a r r i e si nf o r mat i o nb ys e r i almo deo f a s y nc hr o no usdat at r ans mi s s i o n;bas e do npr i nc i pl e so f c o mmo nc ha nne ls i g na l i ngt e c hni q ue si nwhi c ht he s i gnal i ngi sr e mo v e df r o mt hev o i c epat hf o rbo t h anal o ganddi gi t alt r a ns mi s s i o nf ac i l i t i e s . 7 .Si gnal i ngSys t em Number7 -Fo ri nt e gr at e dDi g i t alNe t wo r ks( I DN)f o rbo t h t e l e pho nyandc i r c ui t s wi t c he ddat a.

TELEPHONE AUDI BLETONE SI GNALI NG Tone

Frequencies

 Dial tone

350

Cadence

440

Continuous

 No t e : OnHoo kr ef er st oa

 Busy tone

 Ringing   tone

t e l e pho neno ti nus e ( hands e t0.5 sec ON 480 620 r e s t i ngo nt hes wi t c h)andOff Ho o kr e f e r st oat e l e pho nei n 0.5 sec OFF us e( ha nds e ti sr e mo v e df r o m 440 480 t hes wi t c h) . 2 sec ON

4 sec OFF

1. When was the first complete sentence ever transmitted by the telephone? a. 1860 b. 1876 c. 1892 d. 1905

2. Who invented the first practical system for the electrical switchin of calls installed in 1892? a. !ell b. Watson c. "dison d. #trower

$. What part of the conventional telephone set the transmitter and receiver %nit are located? a. &ial b. !ase c. 'eypad d. (andset

). *he type of transmitter widely %sed in the conventional telephone set a. +arbon b. +eramic c. ,ie-oelectric d. "lectromanetic

5. Who invented the first carbon type transmitter? a. !ell b. Watson c. ray d. "dison

6. *he type of receiver widely %sed in the conventional telephone set a. "lectromanetic b. +eramic c. +arbon d. ,ie-oelectric

7. (ow many %ni/%e tones are %sed for the 12ey dial tone m%lti fre/%ency eypad? a. 2 b. ) c. 7 d. 12

8. n the telephone %nit3 what is prod%ced when the balancin networ in a hybrid circ%it is intentionally %nbalanced slihtly so that the small amo%nt of transmitted sinal is fed to the receiver of the talin phone? a. &ial tone b. #ide tone c. "cho d. #inin

9. *he type of dialin possible for telephone set with rotary dial. a. *one dialin b. ,%lse dialin c. 4oop dialin d. " dialin

10. &* stands for a. &iital telephone m%ltimode f%nction b. &%al tone m%ltifre/%ency c. &ialin time made faster d. &ata transmission m%ltiple filter

11. *he sinal heard on the telephone line that indicates readiness of the central office in receivin address or telephone n%mber a. &ial tone b. inin tone c. !%sy tone d. +onestion tone

12. *he sinal heard on the telephone line which indicates that the called s%bscriber sets is in %se a. &ial tone b. inin tone c. !%sy tone d. +onestion tone

1$. &ial tone3 b%sy tone and rin bac tone are eamples of ::::: sinal. a. #%pervision b. ;ddress c. %sical d. &iital

1). e/%est for service from the telephone is detected at the +entral