BEL_PE_EC_Paper_4

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BEL Place&ent Paper )Technical-Electronics-I*th+

, The noise .i/ure o. a recei0er is a &easure o.1, E%cess noise /enerated2 Bandwidth o. the recei0er 3 'ain o. the recei0er 4 "peratin/ .re5uenc6

2 The ratio recei0er is1, Direct detection t6pe2 #uper re/enerati0e t6pe

3 #uper heterod6ne t6pe4 7one o. these

3 In an a&plitude &odulation s6ste&8 the &odulation inde% is dependent upon1, Modulatin/ .re5uenc6 onl62 Carrier a&plitude onl63 Modulatin/ si/nal a&plitude onl64 Modulatin/ and carrier a&plitudes onl6

4 I&a/e re9ection &i%er is /enerall6 used1, To re9ect the unwanted si/nal

2 To i&pro0e si/nal a&plitude3 To i&pro0e noise .i/ure4 To i&pro0e con0ersion loss

: The 0alue o. a resistor creatin/ ther&al noise is dou;led The noise power /enerated is there.ore1, al0ed2 Quadrapuled3 Dou;led4 $nchan/ed

< Indicated the .alse state&ent1, F &i%er are /enerall6 noisier than F a&pli.ier 2 I&pulse noise 0olta/e is independent o. ;andwidth3 Ther&al noise is independent o. the .re5uenc6 at which it is &easured
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, Its ;andwidth2 Its /ain3 Its operatin/ .re5uenc64 7one o. these

,= The 0elocit6 o. electro&a/netic wa0e in a coa%ial ca;le is

, E5ual to the 0elocit6 in .ree space2 Less than the 0elocit6 in .ree space3 'reater than the 0elocit6 in .ree space4 7one o. these

,? The standin/ wa0e ratio #W! in a trans&ission line1, Is proportional to the load i&pedance2 Is dependent on the source i&pedance3 Is a &is-&atch ;etween the load and line4 Is a &easure o. its power handlin/ capa;ilit6

,@ The standin/ wa0e ratio )#W!+ is unit6 in a trans&ission line i. , The load i&pedance is e5ual to the characteristic i&pedance o. the line2 The load i&pedance is twice that o. the characteristic i&pedance3 The load i&pedance is hal. o. the characteristic i&pedance o. the line4 7one o. these

2> The standin/ wa0e 0olta/e node alon/ a line repeats at the rate o. i. L is the wa0e len/th, LA4 ; LA2 c L d 2L

2, ( 5uarter wa0e line when short circuited at the .ar end ;eha0es like, Pure inductor 2 Pure capacitor 3 Parallel tuned circuit4 #eries tuned circuit

22 The stu; line used to &atch trans&ission line with a /i0en load i&pedance is /enerall6, (nother open circuited line2 (nother short circuited line3 Quarter wa0e trans&ission line4 al. wa0e trans&ission line

23 The s&ith chart /enerall6 co0ers a distance o. , Quarter wa0elen/th2 al. wa0elen/th3 "ne wa0elen/th4 Twice the wa0elen/th

24 The co&ponent /enerall6 used to sa&ple a portion o. the ener/6 trans&itted in a line is, Isolator 2 Circulator 3 Directional coupler 4 7one o. these

2: The return loss in a trans&ission line is a &easure o. , Loss o. the line


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2 #tandin/ wa0e ratio3 Characteristic i&pedance o. the line4 7one o. these

2< The antenna can ;e considered as, Matchin/ the source and .ree space

2 Matchin/ the source to the line3 Matchin/ the line and .ree space4 7one o. these

2= The .ree space i&pedance is appro%i&atel6 e5ual to, ,== W2 2== W3 3== W4 :> W

2? The polari ation re.ers to, The ph6sical orientation o. the radiated wa0e2 The directional o. propa/ation o. the wa0e3 Direction perpendicular to the propa/ation o. the wa0e4 7one o. these

2@ I. u G e are the per&ea;ilit6 and per&itti0it6 respecti0el6 the characteristic i&pedance o. the&ediu& is /i0en ;6, ue ; HuAe c HeAu d Heu

3> The power densit6 at distance rJ .ro& an isotropic radiator with trans&itted power P is1, PAr22 PA2 p r23 PA4 p r24 7one o. these

3, Fre5uencies in the $ F ran/e is nor&all6 propa/ated ;6 &eans o. , 'round wa0es2 #k6 wa0es3 #ur.ace wa0es4 #pace wa0es

32 (s electro&a/netic wa0es tra0el in .ree space8 onl6 one o. the .ollowin/ can happen to the&, (;sorption2 (ttenuation3 !e.lection4 !e.raction

33 i/h .re5uenc6 wa0es are, (;sor;ed ;6 the F2 la6er 2 !e.lected ;6 the D la6er 3 (..ected ;6 the solar c6cle4 Capa;le o. use .or lon/ distance co&&unications on the &oon

34 Indicate which one o. .ollowin/ ter&s applies to troposcatter propa/ation, #ID#


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2 Fadin/3 Frada6 rotation4 (t&ospheric stor&s

3: When &icrowa0e si/nals .ollow the cur0ature o. the earth8 this in known as, Farada6 e..ect

2 Ductin/3 Ionospheric re.lection4 Tropospheric scatterin/

3< (n un/rounded antenna near the /round1, Is unlikel6 to need an earth &at2 (cts as a sin/le antenna o. twice the hei/ht3 Must ;e hori ontall6 polari ed4 (cts as an antenna arra6

3= "ne o. the .ollowin/ consists o. non-resonant antenna1, The .olded dipole2 The rho&;ic antenna3 The end .ire arra64 The ;road side arra6

3? Balun is1, ( circuit ele&ent to connect ;alance line to un;alanced antenna or line12 ( circuit ele&ent to connect ;alance line to ;alanced line3 ( circuit ele&ent to connect un;alance line to un;alanced line4 7one o. these

3@ The slotted line is used to &easure1, #tandin/ wa0e ratio2 Load i&pedance3 #ource i&pedance4 7one o. these

4> In a&plitude &odulation Ec ) , & #in W&t+ #in Wot8 each side ;and a&plitude will ;e1, Ec&A22 Ec&3 EcA&

4 2EcA&4, FM &odulation ;eco&es e5ui0alent to (M &odulation i. , FM inde% is /reater than ,2 FM inde% is e5ual to ,3 FM inde% is 0er6 &uch less than ,4 FM inde% less than or e5ual to ,

42 #A7 i&pro0e&ent o. FM o0er (M8 B is the FM &odulation inde%, 3B2 ; B c 2B d BA2

43 Picture trans&ission in T* e&plo6s, #uppressed carrier &odulation2 *esti/ial side ;and


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3 #in/le side ;and4 7one o. these

44 #ound trans&ission in T* e&plo6, (&plitude &odulation2 Phase &odulation

3 Fre5uenc6 &odulation4 Pulse a&plitude &odulation

4: "ne o. the .ollowin/ is an indirect wa6 o. /eneratin/ FM this is the1, !eactance FET &odulator 2 *aracter di0ide &odulator 3 (&stron/ &odulator 4 !eactance ;ipole transistor &odulator

4< The &odulation inde% o. (M wa0e is chan/ed .ro& > to , The trans&itted power is, $n-chan/ed2 al0ed3 Dou;led4 Increased ;6 :>

4= The isotropic antenna is represented ;6, Dipole antenna2 !ho&;ic antenna3 a/i uda antenna4 7o such antenna e%ists in practice

4? The /ain o. para;olic re.lector antenna is proportional to, The dia&eter o. the re.lector 2 #5uare o. the dia&eter o. the re.lector 3 (perture area o. the .eed4 7one o. these

4@ The para;olic re.lector antenna are /enerall6 used to, Pro0ide hi/h /ain2 Pro0ide pencil ;ea&3 Increase ;andwidth o. operation4 7one o. these

:> Casse/rain .eed is used with a para;olic re.lector to, Increase /ain o. the s6ste&2 Increase the ;andwidth o. the s6ste&3 !educe the si e o. the &ain re.lector 4 (llow the .eed to ;e placed at a con0enient point

:, ( helical antenna is used .or satellite trackin/ ;ecause o. its, Circular polari ation2 Maneu0era;ilit63 Broad ;andwidth

4 'ood .ront to ;ack ratio:2 The discone antenna is


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, ( use.ul direction .indin/ antenna2 $sed as a radar recei0in/ antenna3 Circularl6 polari ed like other circular antenna4 $se.ul as a * F recei0in/ antenna

:3 Wa0e/uides are used &ainl6 .or &icrowa0e si/nals ;ecause

, The6 depend on strai/ht line propa/ation which applies to &icrowa0es onl62 Losses would ;e too hea06 at lower .re5uencies3 There are no /enerators power.ul enou/h to e%cite the& at lower .re5uencies4 The6 would ;e too ;ulk6 at lower .re5uencies

:4 The wa0elen/th in a wa0e/uide, Is /reater than in .ree space2 Depends onl6 on the wa0e/uide di&ensions and the .ree-space wa0elen/th3 Less than the .ree space wa0elen/th4 E5ual to the .ree space wa0elen/th

:: The do&inant &ode o. propa/ation is pre.erres with rectan/ular wa0e/uide ;ecause)indicate.alse state&ent+, It leads to the s&allest wa0e/uide di&ensions2 The resultin/ i&pedance can ;e &atched directl6 to coa%ial lines3 It is easier to e%cite than the other &odes4 Propa/ation o. it without an6 spurious /eneration can ;e ensured

:< The 0elocit6 o. propa/ation )/roup 0elocit6+ in a wa0e/uide is, Less than the .ree space 0elocit62 'reater than the .ree space 0elocit63 E5ual to ;e .ree space 0elocit64 7one o. these

:= ( wa0e can propa/ate in a wa0e/uide i. its cut o.. wa0elen/th is, 'reater than the .ree space wa0elen/th2 Less than the .ree space wa0elen/th3 E5ual to ;e .ree space wa0elen/th4 7one o. these

:? The do&inant &ode in a rectan/ular wa0e/uide is, TE,, ; TE,> c TE2> d TM,,

:@ The characteristic wa0e i&pedance o. a wa0e/uide, Depends on the &ode o. propa/ation2 Does not depend on the &ode o. propa/ation3 Is sa&e as the .ree space i&pedance4 7one o. these

( choke .lan/e &a6 ;e used to couple two wa0e/uides, To help in the ali/n&ent o. the wa0e/uides2 Because it is si&pler than an6 other 9oint3 To co&pensate the discontinuities at the 9oint

4 To increase the ;andwidth o. the s6ste&


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, TE>, ; TE,, c TM>, d TM,,


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2 'alliu& arsenide3 #ilicon4 Metal se&iconductor 9unction

=, "ne o. the .ollowin/ is not used as a &icrowa0e &i%er or detector , Cr6stal diode

2 #chottk6 ;arrier diode3 Backward diode4 PI7 diode

=2 #(W de0ices &a6 ;e used as1, trans&ission &edia like stripline2 .ilters3 $ F a&pli.iers4 "scillators at &illi&eter .re5uencies

=3 #ur.ace acoustic wa0es propa/ate in1, 'alliu& arsenide2 Indiu& phosphide3 #tripline4 Quart cr6stal

=4 ( para&etric a&pli.ier has an input and output .re5uenc6 o. 2 2: ' 8 and is pu&ped at 4 :' is a, Tra0elin/ wa0e a&pli.ier 2 De/enerate a&pli.ier 3 Lower-side ;and up con0erter 4 $pper-side ;and up con0erter

=: The ne/ati0e resistance in a tunnel diode, Is &a%i&u& at the peak point o. the characteristic2 Is a0aila;le ;etween the peak and 0alle6 points3 Is &a%i&u& at the 0alle6 point4 Ma6 ;e i&pro0ed ;6 the re0erse ;ias

=< Microwa0e links repeaters are t6picall6 :>KM apart, Because o. at&ospheric attenuation2 Because o. output tu;e power li&itations

3 Because o. EarthJs cur0ature4 To ensure that the applied 0olta/e is not e%cessi0e

== Microwa0e links are /enerall6 pre.erred to coa%ial .or tele0ision trans&ission ;ecause, The6 ha0e less o0erall phase distortion2 The6 are cheaper 3 ". their /reater ;andwidths4 ". their relati0e i&&unit6 to i&pulse noise

=? ( /eostationar6 satellite, Is &otionless in space)e%cept .or its spin+

2 Is not reall6 stationar6 at all8 ;ut or;its the earth with a 24 hour period3 (ppears stationar6 o0er EarthJs &a/netic pole4 Is located at a hei/ht o. 3:?>>KM to ensure /lo;al co0era/e


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=@ The /eostationar6 satellite launched ;6 India are called, I7TEL#(T2 I7#(T3 C"M#(T4 M(!I#(T

?> ( para&etric a&pli.ier &ust ;e cooled, Because para&etric a&pli.ication /enerates a lot o. hest2 To increase ;andwidth3 Because it cannot operate at roo& te&perature4 To i&pro0e the noise per.or&ance

?, I. the peak trans&itted power in a !adar s6ste& is increased ;6 a .actor o. ,


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, Lo;e switchin/2 #e5uential lo;in/3 Conical scannin/4 Monopulse

@> (.ter a tar/et has ;een ac5uired the ;est scannin/ s6ste& .or trackin/ is

, 7oddin/2 #piral3 Conical4 elical

@, The Doppler .re5uenc6 increases as the tar/et, (pproaches the radar 2 !ecedes the radar 3 Mo0es perpendicular to the ;ea&4 Does not depend on the tar/et 0elocit6

@2 The Doppler e..ect is used in )indicate the .alse state&ent+, Mo0in/ tar/et plottin/ on the PPI2 MTI s6ste&3 FM !adar 4 CW !adar

@3 #olution to the ;lind speed pro;le& is to, Chan/e the Doppler .re5uenc62 *ar6 the P!F3 $se &onopulse4 $se MTI

@4 The (-scope displa6s, Tar/et position and ran/e2 Tar/et ran/e ;ut not position3 Tar/et position ;ut not ran/e4 7either ran/e nor position ;ut onl6 0elocit6

@: In the colour tele0ision s6ste& the su; carrier .re5uenc6 in M is appro%i&atel6, 3 :? ; 4 : c 4: =: d : :?

@< In tele0ision 41 3 1 represents, The interlace ratio2 The &a%i&u& hori ontal de.lection3 (spect ratio4 The ratio o. the two dia/onals o. picture tu;e

@= E5uali in/ pulses in T* are sent durin/ the1, ori ontal ;lankin/2 *ertical ;lankin/3 The serrations4 ori ontal retrace

@? The nu&;er o. lines per .ield in Indian tele0ision s6ste& is1,


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@@ The nu&;er o. .ra&es in Indian T* s6ste& is1, :> ; c 2: d 3>

,>> In a T* recei0er the colour killer1, Cuts o.. the chro&asta/es durin/ &onochro&e reception

2 Ensures that no colour is trans&itted to &onochro&e recei0ers3 Pre0ents colour o0erloadin/4 Makes sure that the colour ;urst is not &istaken .or s6nc pulses

(nswer1-

, a2 c3 ;4 c: ;< ;= d? c@ c,> d,, c,2 d,3 d,4 a,: c,< d,= ;,? c,@ a2> ;2, c22 ;23 ;24 c2: ;2< c

2= c2? c2@ ;3> c3, d32 ;33 c34 ;3: ;3< d3= ;

3? a3@ a4> a


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4, c42 a43 ;44 c4: c4< d

4= d4? ;4@ ;:> d:, a:2 d:3 d:4 a:: ;:< a:= c:? ;:@ a ;


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@3 ;@4 ;@: a@< c@= ;@? ;

@@ a,>> a

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