UNIT-¥ © NOISE te Todroduct ion’ - Norse analysts wm continuous wove rmodulatten 4S cantedout in the -fovm of © parometer Krew oS “prqare Of merit”, clenoted by “a ag Parometer figure oF mertt 2 ts the vattio of of signal to motse vatto “to the ale signal oeio noise vatto of the vecetvers Ths rneans that we Compare sie signal to noise yvatio (= wth the tle signal to noise No . yotio (Si G Nt Jot che vecewer -to evaluate dhe noise Performan Netse tn Comment cation System t= we knowthot to o Commoynication Systern , the messag® signal avelS rom the shransmitter to The vecetver : 3 wmedtorn called channel totee 4 eget TH enery Communication System: che Channel twhoduces on oddttive white quessian reise “in Ane message signal A thus ‘the message which, ge yecetved at the vecetver 18 Aistoyted » “Since the recetver cletects beth message signal & ‘the noise Signal - 4k will “Tepsoduce 0 message signal which contains noise she potse calculation in o Communication sysiem tS cavied out in the form of 4 pavamecer which ts. Known as frqure of merit |Maithematteally “y may be defined as a: a output signal lo noise rato igre of roextl input signal 4o noise vatto = Sofrto Sify Anis expresstony TE is evident that 0. Communication Sy oil have a better noise performance. From system with higher qe, the effect of poise is Small: Noise = -- etdatel net) eof { 4 ee [retstr — BPE (were [syed + soa mot u —Tt - Ry ———> a Generalised equivalent tredel Of © corpmonicat ten System for Meise. caleulation: few assumptions to calculate the figuve of merit -for Vavious — Coramuntastion Systems: Gi) channel noise re aleacys whtte A goussian f= We assume “that the ae always channel Derse nce) rneans that *E as onttormly fo. while noise - Wis erltye band of fyequenctey onder aelributed over the Hence the poser wilt be vNtforg — OVEr the frequency Consideration + spectyom density of chonne! hoise Yonge under Considevatton-@ hus , the otal otee power SN! moy be oblatned —b) , ¢ aking the product of petse power spectrom densi ‘ si 1 nl with the banduidith onder ie, Helol noise power consideration: N = white noise poser spectrom density * Band wie th N= Mp Xk Bw noise, har G Qeussian distyibution: (i) channel rock Hive tle asstime that “the distorbing erect of channel additive This means sfhet “the effect be obtained by addition of “Thus, “the noise, Is always pote. 1s akways ot channel noise reay xed) A noise nt) signal (itt) The noise ot “the ile itt of dewodulator 1S > band pass noise the -fanct band of eaqnol other putetde “his Lange nose Stgnal act the of the incoming fo allow only O wency TEC A vthe, Moise fon of toned civeatt (or) BPE <6 cendered About cower Ley reject all frezuenctes > This means That Signal ying snus, The Bw of the as that we also ejected: alp of detector modulated signal with be same she power gpectom density of. the whtle noise at the iP of she, ernedutactes As Sry = ond 45 shoun in below f. 2 xg:a a re re Sot wine KS PP es fe je noise at the ~ power cpectiom clenstty og the BP whi demoduloter: ‘lp of athe poise TP power Ng im . 4 Yh we tind the D- Te coleulrte the -figere of met noice fe Powe ny -br Bye of for Be op incoming Cotm or Are) obtatned 5 modulated signal athe eto! poise power SNS ey be = z y Bw athe Hoke power Ng ot the Alp of clemed ulated for Am % é Nye Do natm = hem a an psB- SC system 3- detection ot “the ton, ee Notse caleulot athe psB-s¢ System cases ( coherent Agi Chows athe, Hock diagram og OSB- veewer Below Systern -Fro1e Norse print oF view: att) og) coset On| oe a. s 6m Lehn et) comic Ny J No coswiet ei ant Cynchronous cletestor psa- Sc System from noise point oF wiewa . To judee 7 Judge the. performonce of 0. pse-ce system, we Shal} 6 Ys, Caleulate ls figure Of mertt “y! t Oy’. at is given ot = She Siu where, oF olp Signal power w No= ofp poise power powey of the at “the detector y= Alp signal Ne = ‘lp poise poe’ detector now we ghall find off The above ‘yt factors sepeotely ane the wae x mn gu, they values % 4 to calcatete the -fer Inpet signal power ($1) 8 - “the rmoduloted CoS6- sc) signal ot the Input of the. dlemedutetor 48 ven os Sut) = lt) coset t = modulating signal & where, %Ct) cosuict = coaviet gagnal sthus, the UP gignal poeet ay 4S geyen oe the. meany alt) gquare yolue of signal pe St = me.volue of SUE) = 2a) = Tate) cos ets)” - PE) * coe Cue €) = $x)i) @eutpul signal power? — We know thet fn Synchronous detection method: ahe fncoming OS6—SC signal at the detector Snpat 1S d . wultfplied by o synchronous canier Cotuick “thus “tye signal ot the mullipliae olp iS etty= xt) cosuset Coswiet we elt) CoP udet = ult) ss 9.cos (uct ) = xtt) Bet LT + cos 2% = l J ele) = Ut) ,t x0) cos 2 Wet 2 a fs signal as passed “through the Ler thus the signal ot the clermocutetor olp %s gttd= 4 xt) a 2. The ole Signal power at the clemtdulaled olp is Go = rns value OF 4 x(t) = (4 xy y™ Phe a dbe) wb ° 4 Som tai 2 & i fle vi) Input nofse power ?~ the note at -the Zoput ofthe Secetver 4g whtic ussian a neluve this noise ofter passing through ne fond pass filer Cope) is Converted Unto © Bp noise. “the Band pass noise ts ffiven os© 4 - Ne LE) Sinaet nett) = re Ge) Cob oe The tip noise power at the UP Of clemodaletoy lenvied by Na is giver os arty = ne Ce) > ne ce) Ny = fv) Olp noise powers find the Howse yo ot the olp of Now woe Shalt power » demodutetor- The ose signet at the tp of the demodulator 16 2 ap notse, therefore aA te expressed as nlby= Me tt) eogudet -— Ms Le) Sin wet BL) 3S youttiptted by synchronous carrier This notse coset mali pited signal hg ts . agnal ty Synebronoys clemmodulatoy shus 1 the ng te) = nt) coset = [re LE) rosie t> Me Lt) Sin We + Joorudet = ett) coe uiet — 8 Ly sinudet cosmet rycen st nc th Crcostuie t}- b ng te (2 sinact coset] + we re ne ted Coe cosatetJ~ bong OO sino. wet ) «i y+ 4 c ge - Ente t dine Le) Cosauict A ngltsinaaet pre cthe “tems Yo Me Ce yeoracet] ng 4 4S posed “thyough out by the LPF: 4A Af ng EDSIN2 wel ore -fiftteredpee The final noise my CiJat the olp of the clemoduletor AS “Ya PE nol bt) = a ne Ut) athe ofp Meise _POH!LY No = ns. walue OF To LE) iis = ny (8) ed ne?) u Nee Ne 1 Ny No ty Fig Figure OF merit 9! for DEB-se system 48 ,. Geb | Sl Le — ‘ (Sin, Boh, ‘ye x noise calculation in ssB system 3— ga Caingle side band medelation) Ayexe the procedure for evaluating the fugue OF metit of gcse ag Stetlar to chhat of TEB-Se Syste: Ae judge ane performance of O SSB-St System we shall colestate Ws FON Yaw given as Ino Siln3 Us) tnpat Signal powers j= Csp-Sc Signal Ine be expressed a8 Sse Sign { Pp s& eee 7 (Ly coset oth FY sina ct seve ¢ the 4) OQ” aster Loa A ‘_! sign is dev os eek ve the tasy SF nals pee) es the hilbert ‘4 KO srone fort:at the 4 i Ip of “the demedulotior, 9g © The Signal power gee bate ee WW «Yael See ety att) 15 Some totes— a hat the — averaoye power of Ake message signal fax that of US Ketligert ransdortn gue (So) to rmuttiptved YO SY Gi) outpet signal e vier chye noes local caw SSB- SC sagnal As Cosvict: sole eth) = (ated cosudet gay cer sinusct Jeoe set = pice) com del ay cey ined cos et eck) = sacl) peo’ wit Jt La.) ces canusect coset J = 4208) Crecoseet yt gent nnet ect) 8 passed Ahvoagh fhe LPF: which vegerts all the ers cosrwet ¥ gin ose t- dence the lemoduiated OF signal 6 eters 6) olf srqnel powey ak the clernodulat ov as sor we * Logg a S184 = v, tnpat noise powers demodulator rs white qhe lp of the Norse apie: passing thyough the ee BP Nose. The itp BPN IS the notee ot Gaussian Worse converted 4 yte ere 1S ny (4H) =%e (4) Cosuack ~ ng CE) sinwiet piotse power oF “the ap OF deinvd ulate? deneled by ws given by en cee ne Ny fe = Dy CO)Tw op Oise Powe VE we shail find he netse poaey Me at the olp of demedutators note signal nt } Ae mmultip ted by synchiontos Cantey Signal Cosel tn clemedulador. the ‘mutttplted Signal ng ts ha ence) Cos wat & - nett stout coswet e[nct? cose & Cosaiet = ne cer eoset = ne Lt) Stowe Caco8 ret] - MS [asin wet Coste J a = Yo ne Ub) wet J- ne le sine de® = its (+ cos 3 o. LE: The texms gin(2 ct) We \ 3. grgnal ng iS wossed inough Vy. ne HO cos Qt t) A by the LPF Oise yy. rs) axe prteved 08 his means that Abe ganal noise ofp ak the demedulatot a Mylt) fee, Melt) = Y-Me &) Tig Ut) = Vane ue) qhe out pet potse Powe! Np wtll be emngnalud of elt) No No = ng bo) = My nec) ant ‘ No wo = Ya 8 She Vy, Ny? p'gor geg-sc syclem ts whe ae oY, 7 Salg 7M My Figure of ment tNotse calculation tn Ampttiude. modulation system ¢ Aviepe | j etector metho dd 47 © 1G) inpet signal powert> We Knee thet 10 Aen systems Oo large carrier as =o Ueper lower gide band , Now, accompanied potth he sthen the UP nell) VS The signet additive poise gg expressed oS [ne xte)s Co 4s qrven os, wog aide bends ae the ctetecter Sant) = Alp Signed gti & * n, le) the power $1 Ges yolue of conter + MS S&F y, (ar* ed) powet ($08 ~ envelop® detector etl be the envedpe Le thus (to. find the @) ovtpot stgnel ole of the aint signal Sar og the fim detected ol cys TAX = caren) gagnel . x leyy coset any) ue) eS Wet ~ ngs Vo naet Sam J coset * Me nipulatten "© becomes Cuct t gto] de a phese angle of Samlt) * ariqonome QTE no darn GE) = ALD C08 acy A Ole) we compltto: ALES = Tear gu) = Tent _ AY © aa og both siqnal A noise. the nose “the analysis o fie where (£) AML} #e Ce) the envelope att) depends on “the signal A qotse: Performance ME cases, a onder col be Convtedout ferG4) Large noke case (1) Small noise ) Small noise coset Notse as taken te be ynuch gmatler than atynal pee, NUYS (are) fe phase vepresentatton oF ervelope ACE 16 shown ay below 417 “i actly “ nglt) a_i ee lt atult) te) qin Phasor diagram o€ the envelope Att)- wy HELE) Is much smaller then gu) = 04 the nevelope ALE) becomes alt= arvtt) ant) = The syne power So F polse poor No at “the olp of the cletected, OY be calculated aS | ole stqnal power So = Mm. g- Value Of useful signal 24) eh lt) Gn) IP Norce power (Nt)t- ne = Pre D OF BPWN yew tam) Snj = NM yotm astm 2m a | hh 2 | > ! \ : -fe 6 fot clensvty of power Spectiom she bane pass uhtte rotse, at the Tp of clemodutelor:KR outpat noise powers att) atthe air et the delete detector the power spechom clenctty gtven as snc) =h Sothe olp nots she notse signal te ne be) with Spo 9 powey = GMo(ed) KBW = ry eotme ayer erquie of meitt Y= SelNo pandbos Ylase] w) Loxge nowe Case d— In tris Case nt) 27 4 the envelope of the 4nlt) tere the noiwe teyms- snow dorminate « roodalated signal ot the Up ot he. clelecley 4s expressed ak att) = Cat eee nel) P40 CO —— =f crv cen ane fatrjene? wt oety clominotes ONeIthe Signal So Now the notse more (ae xttyy evr con ae = Pre caang dae ance Ca ei] ee ) hy? Cer t nd) ioe negleated ALE) becomesseb eud= [ a, — i ¢ { WeECE ANE Ct) 4 OU) = rant! —) Ne LE) t)< gr “ Alt)e RLO jan tatty) De Ret) (Ut) St te)” 5 Ct) [b+ tot ct) | cso] - Ru) = Yo y neo] cy ED — cosolt) RULE) —o8 the Hote RUE) SID ATH+XLE) B® Cam be approximate -fosm of expyessing an 5 went pt = RUE) [uae Creech] cos ott) | RU) ale) = Rk) 4 Acoso Ct) + vltjcose Lt) Mexe the tem atk) iS mattiplted with o. large noise serm cos Oct) * trence xt the notse AS she nod uloting ringette” mosses TE Canter ne useful Rofarmeion the loss GUL) tran envelope detector due to as known aS the y dannot be Separated form dem “LO 46 Completely Of the Message the presence o€ the loage noise S shyeshold efeect a Threshold etteet in On envelope letectoy ¢- as lange compared to “the signal oct the when o noise the detected olf hae ilp of the envelope dele ctor, rnsg, signal completely wevingled wth notse- shat ty the UP sin vatio (Sins) yy below a mr TE MEANS called threshold level) tne poice Cerkain level, deimtnoles Over The MSY Signal:sthreshold ts detined as value of the SyIN% below atch © rauch moore vopidly than “the Ip the Soly, detertovotes “to notse sartio signal tle siynal Evaluation of Noise tn angle rmodulated systern z- To delevming the Mose Performance oF angle modulation ghows the block liagram of an angle System. Below Pq: System: yr? ut) angle Ange [Sica Olea [ia HE ae tt —— Sam ~—— Rx 1 + choanet | modulation cthe generalised form OF angle modulatten t represented as gut) = A cot luck + EC} Hag ces Cafe +4} Wheres A. = omplttude of Conley Signal ote frequency of Canter geqnal gusy= phose angle: dle kp att) — for phase modulation (Pm) Gd= 2WkE f 1b) dt for frequency modulation Gm) genstlivrties Of the phese 4 figueny kp A ky ove the maedulators. jeepentively: channel noise. nytt) at the ap of the clemoduloter Nou ‘the spectral density Cesd) Smt fe a BR NOTse With Power Bw 2 Cote ts)Thus nose O¢ Ut) mey be expressed af 4 -ngll) stnutct ne lk) = Mec UE) cose c eng LEdstdowtct) Ut) cosru te modig¢ied 2S =e fibove 4 can be nytt) = yt) CoS Cuiet rol | eyeos Cafe + ult) J =Y where vit) = { ne tay ene ott)+ “Tan! (ne Ca pte rt) cose lt) & nglb= y+)sin ott) ectt~ cawiel ca “tive shold ef “threshold eggect IS yatio that givel the output Signe jess. Ahan the valee predicted by the usual e -Rormul® assuming O gmail noise POSS ¥F degined as the mintmorn tht sto metse ( to notse yatio net signa so Hers exnphosis *7 Joost the aq oil be modulating aprg rere y the. as called a pre pre - 4e we Signals: qhen sty ot high yreduloting ampltiude og highest Pes sency moalulatting posstele le gmpyove the rose boosting of Ronn ne emphasis. haghe® frequencies alee aeney rnoclulating signal 4S achieved Boosting of higher iq a: athe by using Ahe pre ~ emphast § modulating A siqnal 1s passed petore applying th to the tm ctcatl Of jhvough @ HPRS medulatoy- seitter,i ® LT t Baek * modulator Pree empha deel modulecting Signal ole em sl \ J yt ta) t= pre eermphasts Ctveatt ale ee ' ~? boy Pre-emphasis chaactertsttes > The preemphass ckt ts used od the Tr. @ De~ ernphass i ‘i dulatis she ont trigher ™O glating zs rulltgted (ov 4 de-emphasie. cal boosting given to the Prox yencies tn the prowess of pre-emphasis by a process Calle compen soted at the yeceiWrey o tow pass Tilter. Be — emphosis Civeutt Corresponding yesponse — CAVE: — tt 48 oO freguency De-emphasts Y erm =e ‘ R aa | ta al demodulated |} de 1 \ ‘ ' Ae olp signal qi- De- emphasis Ctreatt:ole a [> v ae s- De - emphasis Crreurt chavocteristics & De- emphasts ciyentt ta used at athe yecetver?o -tp the. De~ emphasis cAavcutt zs applied Set goes on decreasing Demoduloted em dye. reactance of wetth ancrease T9 fm de - emphasts civextt Will also yeduces- 4 the output ofSl. Capture sides | © wri a shosk nok on Gphne ebbed in EM. (4- ars) b ? In FM ays, the signa Can be aPpecied by another Frequency modulated Riga) whose Frequeny i& cloge ie Me Cartier Prequenug ee the desized FM- Signs) Tren the ‘receives may Jock Kuch an fnkrference Zig and Suppressed the desired FM- Signo) de fakrperence Aligned becomes move Atronger than the desired Kignod. & when ‘the adrergy ef ia desized Aigna) and interference Bigral axe nearly equoy, the neceiver Jocks &iexperence Signal For Sometime and desired Aigrod fur the gowe Hime ond thig Goes on Tardomly and recetver Caphires the porger Aignad. 1 ee | te _ ” gral. Thid ef bed fe Known a& Gphure- effect. 3. 4 _WTU &P 1: Fa Tseshold EfPEd 94 ihe Reduction :- Jan-2012 617 explain pry threshold Efe ty Fm-Syglin- vou (6-marng) G Te GNR) op an Fm-Signod 14 valid only Fe die Ena) mesured at De Preyueauy discriminabus Fpus- fa Very much Greoder Thar Unity. app be, Gag) = set is Valid $8 CNR 2b A TE CNR <1 then Fx aignal ig Conupied by noise and Fit recetver breaks down. & i& Giled Teshold ef ber FM. be, Treshold ed 14 defined of He mintmum Carries to noise Totio Cow) that gives the Gua) not less than te Value predicted by the UU SNR formula axsuming a VBiS2 Power. Ly Te reshold efsede Gm be avoided by keeping =carrier bs nvidse Yodio of Fmt. Aystion much greater than 1. | Ly when enR¢4 FM receiver breaks down due t Fri-threshold effey- Tris poi) 14 Gilled Fseshold poid - FM TAreshold teducion -— Taa-2 012 vT0 AARE DARN AAARM Explain about the EM-Tzeshold ekbed Qed Th seduction Melad tu. &m) Ly Fit Threshold can be Teduced by using Em. dlemodulams With negative Fedback by “Ustog & Phase- Locked Loop demodulator. Such devices are reyered of Extended Anseshld demodwasus . Ly Fm. demodulahr with negative feedback fm algo known 0% FMEB-demodulatur , FPGAS Block di ay iagreum of EME demodulahss fur theesheld Tlugion ON ARIA ARR Ly Figured, shows “the bJock diagram, p PME demodulaty Andhis dyslam Joo) oscillator ts Teplacd by Voltage Conbroiied OAci \layor . 1S The Tostentaneou, output preauenay of Buch ¥Co F& Conblled by dlemodwheded output AZre . 4 he banduofeli of neice ti ~tohacd, the PME Teceiver ‘responds, {precisely ke bard of nsise Out th veo-traun, hus Ue PMFE receiver ack a3 a tracking Prites, Kha Can rack only Gu Shily varying Frequenay oP a sy,“Wide-band Fm aigral. _ Lb Therefore 14 responds only Js anarren) bard of noise Curtered abowd roy Pe og a Tew FMEG Ta ves allows a Threshold &xjension sup 5de be tdg a Ahown fh Fiqure.g. id CNR Se, FT Ode . Sdabtde ELS" Graph showing. the Extended Heeshold ag ieU ‘>. FMFR demodwWader wsian negative Feedback provicles Bde tb #de enhancemedt tr ENR) & fd always moiintains CNRY4 and T+ aveidg FM-Threshold effect- aver: si 13 Pre. Pre-emphaaig and De-emphasié & eM EM om Q> Witk civcuilg ard CharateaTstics, explainthe Pmportance °f pre-emphatig and De-emphasig in pm -Aysiens- vite VTP ~8K- 1 pre-emphasig and Oe-emphasig methads ave Commonly Uses) by EM -transmiter and FM~Teceiver ‘wespecsi velyp te fpr Dy Threshold. pre-empharig and De-emphasig are Simple RC networks Uded ts Pnprevetharshold upts 12d@ & Iéde Ly Fiquved Shows te Fit trantwiter 17! poe- emphasis Prue r faving transfer -Punuion He Cf) . Ly Figuaca, Showa the pre-emphoria Piller -used belt Fe —rransmities . aeS22 pre-emphasized FE m- odput qn 442 : iS PtHer fin Er cheansmite Fig + Uae Precenghaais filer Io Rumen air + pre- emphosts Pi lter@ ciscsd t- RRA pen ee — Ly pre- emphosig ctreuid (a High- pars- FRY shransqer uadion Shown fm iguee2- ; [He ®Y FF) with my) fF de L—- - --¢4—passbani+ a ods} i ‘ e Frequenup (4) Pxg-emphasis o Me Cf) . ECUsS Fig2: Pre-gaphosia 4ille cereus4 diagram woth Frequency ‘tes 2. Ls To tmprove Gur), ab tie M-Modulahir ourpud, the Kigh Preque- NY Componenti of Die message Aigna) m(+) ave arH dally Emphasized at the sransmites, before the Modulation - psvcess §- Taq Shown ww $39.4. Ly ABee pre-emphasis, met) occupl es enfise Targe op bardusidth oxgiqned. Then od the Prequenuy didoriminatur (Fm-demodulabr) of Fon receiver, inverse eperation of pre emphatia Gilled De-emphasis 1s pexpurmed - * Figure Zz, shows the rq Teceiwer With deemphasis Pa lfee raving Prepuenuy respon IH). © De-emphasia Piller/clreuit 18 “Used abiey FM-demodulaboy OA Brown ty Figued -y =o Sth) x) mat) J Be- emphasis © rfice Filter > Hyp nit) . * igus: Pr zeal Wits Desenphaais fk De-empharias Filey @ Gr cust afer voit “Up be emphasia Circus 1% a Bien RC- Lowpars $5IKY ee OR Ahown tm FIQUX4, Presuieaty respons Wy] : tn Freweyy Go becemphat ie @ Frequenu) vesperse F1g-42 De-emphasic Hltte cicquit diagram & 1B Preqeny 7? Ly High- Prequenuy Components patud ab De onspud df em-demy - dudodir elp signa) (mit) are de-emphasized ts Tesrort ie OrIgina) message Ligno) power ALshibufion . b Dusiog , de-emphasis process , High Pre quenup Componente of. the noise ae algo reduced andtheeby ebbicently output Gigrad te wise TH0,(SNR), . Ly The Freyurnuy aesporne 9 de-emphar's 4ilter & De emphasis Fier ave relayed by, ‘ Hae P= Foe \ ye] d eitit nig ond |H, (P= 145 ade - bhese [Ha G)| =Lythe ethed ef de-emphasia Fitter on output “eve Sperm 18 iWustratid ty FIQuK-s” oudprd Noise Spectrum afer Deemphatis Fortenuy bocta s Naurss EMtect 4 De-emphasis fe 00 output Noise PENS SE@) Showa ontpud noiac Spermum ishich 1a, pazabolfeally lncrraaing—bwards the edge } TW. Tepe GNQ}, reduces befine deemphasis. Ly when Noise 16 Pilleaed by Teng de-emphosis “Hiker Paving. Preguenuy Waponk Chow ba 45g SQ, the owpad riviee Speciatey APY cle-enphasiA decomes almost Ala oF tW'HE OR @ reser Gna), increases and 7+ avoids FM- Threshold - o> Pre- emphoria and De-emphosis Grou Ax Stpectively mused JB frcveate QAR) of thy cransmilter Cbefme modu labia) ard weiiver (aperdemodutation) 3 EM- CRGm wpertirely we end 33