topics final quiz reviewer

8/19/2019 Topics Final Quiz Reviewer

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Acoustic & Broadcasting [MITRC refresher]

1. Which best describe the sound wave?a. It may be longitudinalb. It is always transverse

c. It is always longitudinald. All of the above

2. Which of the following can not travel through a vacuum?a. Electromagnetic waveb. Radio wavec. Soundwaved. Light wave

. !hrough which medium does sound travel fastest?a. Airb. Waterc. Steeld. "ercury

#. $%eed that is faster than that of sound.a. &ltrasonicb. Supersonicc. $ubsonicd. !ransonic

'. What is the s%eed of sound in air at 2()*?a. 1087 ft/sb. 11(( ft+sc. 112, ft+sd. 2(( ft+s

,. *alculate a half wavelength sound for sound of 1,((( -a. ' ftb. 1( ftc. 0.035 ftd. 1(( ft

/. !he lowest fre0uency that a human ear can hear isa. ' -b. 20 !c. ( -d. 2( -

. $ound that vibrates at fre0uency too high for the human ear to hear over 2( 3-4a. $ubsonic

b."ltrasonic

c. !ransonicd. $tereo

5. !he fre0uency interval between two sounds whose fre0uency ratio is 1(a. #ctaveb. -alf octavec. !hird6octaved. 7ecade


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1(. A 1, 8- sound is how many octaves higher than a '(( - sounda. 2b. 5c. #d.

11. $ound waves com%osed of but one fre0uency is a+an

a. Infra soundb. $ure tonec. $tructure borned. Residual sound

12. $ound wave has two main characteristics which area. -ighness and loudnessb. !one and loudnessc. $itc% and loudnessd. Rarefactions and com%ressions

1. When waves bend away from straight lines of travel9 it is calleda. Re:ectionb. 7i;raction

c. Rarefactiond. &efraction

1#. !he am%litude of sound waves9 the maitchb. Intensityc. 'oudnessd. -armonics

1'. It is the wea3est sound that average human hearing can detect.a. $>L ( d@b. !hreshold of hearingc. Reference %ressure 2 < 1(6'+m2

d. () b) c

1,. What is a device that is used to measure the hearing sensitivity of a %erson?a. (udio*eterb. B!7Rc. $L"d. $%ectrum analyer

1/. What is the device used in measuring sound %ressure levels incor%orating a micro%hone9am%liCcation9 Cltering and a dis%lay.a. Audiometerb. B!7Rc. S'+d. $%ectrum analyer

1. What weighted scale in a sound level meter gives a reading that is most closely to the res%onseof the human ear?a. ,eig%ted scale (b. Weighted scale @c. Weighted scale *d. Weighted scale 7

15. Dor aircraft noise measurements9 the weighting scale that is used is =====.


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a. Weighted scale Ab. Weighted scale @c. Weighted scale *d. ,eig%ted scale -

2(. It is the device used to calibrate an $L"?a. "icro%hone

b. $istonp%onec. !ele%honed. Dilter

21. ===== is the sound %ower measured over the area u%on which is received.a. $ound %ressureb. $ound energyc. Sound intensityd. $ound %ressure level

22. A measure of the intensity of sound in com%arison to another sound intensitya. >honb. -ecibelc. >ascal

d. Watts

2. *alculate the sound intensity level in d@ of a sound whose intensity is (.((/ W+m2.a. 5' d@b. 51 d@c. 8 dd. 1(1 d@

2#. What is the sound %ressure level for a given sound whose R"$ %ressure is 2((+m2?a. 2(( d@b. 2( d@c. 10 dd. 1# d@

2'. What is the sound intensity for an R"$ %ressure of 2(( >ascal?a. 5( W+m2b. 8 ,/*2c. 1( W+m2d. W+m2

2,. !he sound %ressure level is increased by ===== d@ if the %ressure is doubled.a. b. #c. 'd.

2/. !he sound %ressure level is increased by ===== d@ if the intensity is doubled.

a. 3b. #c. 'd. ,

2. If four identical sounds are added what is the increase in level in d@?a. b. #c. 'd.


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25. !he transmission of sound from one room to an adacent room9 via common walls9 :oors orceilings.a. laning trans*issionb. Re:ectionc. Refractiond. Reverberation

(. ===== is the continuing %resence of an audible sound after the sound source has sto%.a. Dlutter echob. $ound concentrationc. $ound shadowd. &everberation

1. Re0uired time for any sound to decay to ,( d@a. Echo timeb. &everberation ti*ec. 7elay timed. !ransient time

2. A room containing relatively little sound absor%tiona. 7ead roomb. Anechoic roomc. 'ive roo*d. Dree6Celd

. A room in which the walls o;er essentially 1((F absor%tion9 therefore simulating free Celdconditions.a. 7ead roomb. (nec%oic roo*c. Live roomd. *losed room

#. *alculate the reverberation time of the room9 which has a volume of /(( ft and total sound

absor%tion 1#( sabins.a. (. secb. .' secc. 3 secd. (.' sec

'. It is an audio transducer that converts acoustic %ressure in air into its e0uivalent electricalim%ulsesa. Louds%ea3erb. Am%liCerc. @aGed. +icrop%one

,. ===== is a %ressure ty%e micro%hone with %ermanent coil as a transducing element.

a. -yna*icb. *ondenserc. "agneticd. *arbon

/. A micro%hone which has an internal im%edance of 2' 3H is ===== ty%e.a. ig% i*pedanceb. Low im%edancec. 7ynamicd. "agnetic


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#/. It is an enclosure used to %revent front and bac3 wave cancellation.a. Louds%ea3erb. 7riverc. a9ed. Drame

#. A circuit that divides the fre0uency com%onents into se%arate bands in order to have individual

feeds to the di;erent drivers.a. $us%ension systemb. -ividing networ c. "agnet assemblyd. >anel board

#5. ===== is early re:ection of sound.a. 6c%ob. >ure soundc. Reverberationd. Intelligible sound

'(. oise reduction system used for Clm sound in movie.a. -olby

b. 7@<c. d@ad. d@3

'1. &sing a micro%hone at less than the recommended wor3ing distance will create a ===== whichgreatly increases the low fre0uency signals.a. Roll6o; b. $ro:i*ity e;ectc. 7ro% outd. one of the choices

'2. What is the unit of loudness?a. Soneb. >hon

c. 7ecibeld. "el

'. A unit of noisiness related to the %erceived noise levela. hon

'#. What is the loudness level of a 18- tone if its intensity is 1 < 1(6'W+cm2?a. 1(( %honsb. 1(' %honsc. 110 p%onsd. 1(( %hons

''. What is the %rocess of sending voice9 s%eech9 music or image intended for rece%tion by thegeneral %ublic?a. avigationb. !ele%honyc. roadcastingd. "i


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a. Jerob. 20 !c. 1( -d. 2( 8-

'/. !he transmitting antenna for an A" broadcast station should have a ===== %olariation.a. =ertical

b. -oriontalc. *irculard. Elli%tical

'. !he %art of a broadcast day from , >" to , A" local timea. -ayti*eb. ighttimec. @ed timed. E


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c. M-Dd. MLD

,,. What does the acronym $!L stand for?a. $tation6to6lin3b. $ignal6to6loss6ratioc. $hout6to6live

d. Studiototrans*itterlin

,/. Bne of the main considerations in the selection of antenna site is A"4a. 4onductivity of t%e soilb. -eight of the terrainc. Elevation of the sited. Accessibility

,. Bne of the broadcast transmission au"

c. I$@d. -S

/#. What is the %ilot signal for stereo D"?a. #.2' "-b. 1( 3-c. 1 ?!d. 8-


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/'. With stereo D" transmission9 does a monaural receiver %roduce all the sounds that a stereodoes?a. @esb. oc. Either a or bd. either a or b

/,. Where is de6em%hasis added in a stereo D" system?a. @efore the matri< at the !Ob. @efore the matri< at the ROc. After the matri< at the !Od. (fter t%e *atri: at t%e &A

//. Where is the %re6em%hasis added in a stereo D" system?a. efore t%e *atri: at t%e BAb. @efore the matri< at the ROc. After the matri< at the !Od. After the matri< at the RO

/. !he normal fre0uency for an $*A subcarrier is ===== 8-.a. 7

b. /,c. d. 15

/5. A monaural D" receiver receives only the ===== signal of a stereo multi%le< transmission.a. ' C &b. L P Rc. @oth a Q bd. ,/ 8-

(. When fed to the stereo D" modulator9 in what form are the L P R signals?a. ADb. -SS4c. 15 3-

d. 3-

1. An additional channel of multi%le< information that is authoried by the D** for stereo D" radiostations to feed services such as commercial6free %rogramming to selected customers.a. $!Lb. E@$c. EIAd. S4(

2. !he class of D" station9 which has an authoried radiated %ower not e


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a. *lass 7b. *lass *c. *lass Ad. 4lass

'. What ty%e of broadcast service might have their antennas on to% of hills?a. D"

b. A"c. !Md. ( D 4

,. -ow are guardbands allocated in commercial D" stations?a. 25 ! on eit%er sides of t%e trans*itting signalb. '( 3- on each side of the carrierc. /' 3- deviationd. 1' 3- modulation

/. -ow many commercial D" broadcast channels can Ct into the bandwidth occu%ied by acommercial !M station?a. 1(b. 2(

c. 30d. #(

. -ow many international commercial A" broadcast channels can Ct into the bandwidth occu%iedby a commercial !M station?a. 1((b. 2((c. 12'd. 00

5. What 3ind of modulation is used for the sound %ortion of a commercial broadcast !Mtransmission?a. >"b. +

c. *Dd. A"

5(. Estimate the bandwidth occu%ied by the sound %ortion of a !M transmission in &$.a. 2' 3-b. (( 3-c. 80 !d. 2(( 3-

51. What is the main reason why television %icture signal uses am%litude modulation9 while voice isfre0uency modulated?a. @etter eciencyb. Eliminate attenuation of both video and audioc. "aintain synchronied scanning between transmit and received videod. Bo *ini*i!e interference between signals at received end

52. !he %icture and sound carrier fre0uencies in a !M receiver are ===== res%ectively.a. #1.2' "-9 #'./' "-b. #'.2' "-9 #1./' "-c. #1./' "-9 #'.2' "-d. 5.75 +!) 1.25 +!

5. What is the se%aration between visual and aural carrier in !M broadcasting?


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a. 1.2' "-b. .5 +!c. './' "-d. (.2' "-

5#. What is the se%aration between the lower limit of a channel and the aural carrier?a. 1.2' "-

b. #.' "-c. 5.75 +!d. (.2' "-

5'. What is the visual carrier for channel 12?a. 205.25 +!b. ''.2' "-c. ,'./' "-d. '5./' "-

5,. What is the aural carrier for channel ?a. ,1.2' "-b. ''.2' "-c. 5.75 +!

d. '5./' "-

5/. What is color subcarrier for channel 2?a. ,. "-b. 211.2' "-c. 58.83 +!d. 21#. "-

5. If the sound carrier for &-D channel 2 is '25./' "-9 what is the fre0uency of the tuners localoscillator9 when turned to this channel?a. 571 +!b. '11 "-c. #5 "-d. '(( "-

55. What is the fre0uency tolerance in the color carrier of !M broadcasting?a. 2 3-b. 2( -c. 10 !d. 1 3-

1((. What is the e


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d. licer

1(. What %ercentage of the %rimary colors used in color !M are needed to %roduce the brightestwhite?

a. 30E red) 5E green) 11E blueb. F red9 F green9 F bluec. '(F red9 2F green9 22F blue

d. 'F red9 2(F green9 22F blue

1(#. !he color with the most luminance isRed

@ellowreen@lue

1('. $u%%ose the signal from a color camera has R(.9 (.# and @(.29 where 1 re%resents thema


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112. Which of the following is the color video signal transmitted as am%litude modulation of the .'"- * signal with bandwidth of ( to 1. "-?a. I signalb. K signalc. S signald. O signal

11. Which of the following is the color video signal transmitted as am%litude modulation of the .'"- * signal in 0uadrature with bandwidth of ( to (.' "-?a. I signalb. F signalc. S signald. J signal

11#. !he ===== a;ects the di;erence between blac3 and white on the %icture tube and controls thegain of the video am%liCera. @rightness controlb. Molume controlc. >ower controld. 4ontrast control

11'. Which of the following is not a re0uirement for a color !M signal?a. com%atibility with b lac3 and white receiversb. Within , "- bandwidthc. $imulate a wide variety of colorsd. unctional wit% baron super antenna

11,. -ow many electron beams actually leave the electron gun of a single6gun color *R!?a. 1b. 2c. 3d. 1+

11/. What is the di;erence between the sound carrier and color subcarrier fre0uencies?a. 1.2' "-b. .' "-c. #.' "-d. 0.2 +!

11. What does as%ect ratio mean?a. &atio of t%e screen widt% to its %eig%tb. Ratio of the screen height to its widthc. Ratio of the screen diagonal to its widthd. Ratio of the screen diagonal to its height

115. What is the as%ect ratio for -7!M system?a. #+

b. 5+/c. 15+,d. 1/

12(. !he signal that will give the e


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121. Which of the following re%resents the intensity of a given color?a. -ueb. Saturationc. *arrierd. "onochrome

122. !he ===== ensures that the electron beam will stri3e the correct %hos%hor dot on the !M screen.

a. *oatingb. (perture +as c. 7i%le


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d. 1'/,2' -

11. What is the highest video fre0uency set by the D** for commercial !M?a. .2 +!b. 1' "-c. , "-d. '.' "-

12. What determines the ma


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1#(. Which of the following fre0uencies is wrong?a. 1'9/'( - for horiontal sync and scanningb. ,( - for vertical sync and scanningc. 19'(( - for the e0ualiing %ulses and serrations in the vertical sync %ulsed. 31)500 ! for t%e vertical scanning freuency

1#1. !he camera tube that uses selenium9 arsenic and telluriuma. >lumbiconb. Midiconc. Saticond. $ilicon Midicon

1#2. !he com%onents of com%osite video signal areNa. *hroma signalb. @lan3ing %ulsec. $ynchroniing %ulsed. (ll of t%ese

1#. What is the smallest amount of information that can be dis%layed on a television screen?

a. @li%b. @urstc. $i:eld. @its

1##. It is the 0uality of the !M %icture after im%erfectionsa. As%ect ratiob. "tili!ation ratioc. A1d. "onochrome

1#'. What section of a !M receiver determines the bandwidth and %roduces the most signal gain?a. RD am%liCerb. Audio am%liCer

c. I a*pli>erd. !uned circuit

"odulation U"I!R* refresherV

1. A portion in a communications system, which processes the information so that it will become suitable to the

characteristic of the transmission medium

a. Encoder

b. Modulation

c. Transmitter

d. Multiplexer

2. Signal whose physical quantity aries continuously with time

a. !igital

http://ecehandouts.blogspot.com/2010/10/modulation-mitrc-refresher.htmlhttp://ecehandouts.blogspot.com/2010/10/modulation-mitrc-refresher.html


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b. Analog

c. !iscrete

d. "nformation

#. !igital information is processed with a specified degree of

a. $idelity

b. Accuracy

c. Sensitiity

d. %orrectness

&. "ndicate the oltage leel in d' with reference to one olt. (his unit is used in ideo or () measurement

a. d'*

b. d'+

c. d'm

d. dBV

. *hen the power ratio of the output to input of a circuit is 2--. *hat is the gain in d'

a. 23

b. &/

c. 0 2#

d. 0 &/

/. *hat is the reference leel for random noise measurement, $"A weighted

a. – 82 dBm

b. 0 - d'm

c. 0 d'm

d. 0 33 d'm

3. A 1- db pad has an output leel of 4#d'm. (he leel at the input is5


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a. 1# d'm

b. 0 3 d'm

c. 1 d'm

d. 7 dBm

. A power leel of - 6* could be expressed as5

a. 1./ d'm

b. 0 &.# d'm

c. 1 d'm

d. – 13 dBm

. A system haing an input power of 2 m* an output power of -. m* has a loss of5

a. 2. d'm

b. 3.98 dB

c. #. 6*

d. 1. m*

1-. "s the reduction of signal amplitude as it passed oer the transmission medium

a. 7oise

b. !istortion

c. Attenuation

d. "nterface

11. Signal waeform perturbation or deiation caused by imperfect response of the system to the desired signal

a. 7oise

b. Aliasing

c. Distortion

d. "nterference


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12. Signal attenuation can be corrected by

a. $iltering

b. Modulation

c. Equali8ation

d. Amplification

1#. Signal contamination by extraneous or external sources, such as, other transmitters, power lines and machinery.

a. 7oise

b. !istortion

c. 9armonics

d. nterference

1&. *hich noise figure represents the lowest noise

a. 1.! dB

b. 2.- d'

c. #.3 d'

d. &.1 d'

1. !enote the interference of noise in d' aboe an ad:usted reference noise. (he ad:usted reference noise leel was a

1 +98 tone, set at 0 d'm

a. dBa

b. d'm

c. d'a-

d. p*p

1/. A more precise ealuation of the quality of a receier as far as noise is concerned.

a. S;7

b. )S*


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c. "oise factor

d. 7oise margin

13. 7oise figure for an amplifier with noise is always

a. - d'

b. "nfinite

c. =ess than 1

d. #reater t$an 1

1. A passie circuit, usually consisting of capacitance and;or inductance, that is inserted in series with the a4c power

cord of an electronic deice which allow the /-498 current to pass and suppressed high frequency noise

components.

a. "oise filter

b. 7oise limiter

c. 7oise floor

d. 7oise quieting

1. A circuit often used in radio receiers that preents externally generated noise from exceeding certain amplitude.

(hey are also called noise clippers.

a. 7oise floor

b. 7oise filter

c. "oise limiter

d. 7oise clamper

2-. Extra4terrestrial noise is obserable at frequencies from

a. - to 2- >98

b. 8 %$& to 1.'3 #(&

c. to ?98

d. 1 to /- M98


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c. 8,.- percent

d. #.# percent

2/. A carrier of - +98 is modulated by a #.4+98 sine wae. (he =S' and @S' are respectiely,

a. 3# and 3+98

b. 87-.! and 883.! (&

c. #. and 3/. +98

d. 3 and 3# +98

23. $or 1-- percent modulation, what percentage of carrier power is in each sideband

a. 2! percent

b. ##.# percent

c. - percent

d. 1-- percent

2. An AM signal has a carrier power of *. (he percentage of modulation is - percent. (he total sideband power is

a. -. *

b. 1.- /

c. 2. *

d. &.- *

2. An AM transmitter antenna current is measured with no modulation and found to be 2./ amperes. (he percentage

of modulation is

a. # percent

b. 7, percent

c. &2 percent

d. percent

#-. (he typical audio modulating frequency range used in radio and telephone communications is


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a. - 98 to +98

b. - 98 to 1 +98

c. 1-- 98 t 1- +98

d. 3,, (& to 3 (&

#1. An AM signal with a maximum modulating signal frequency of &. +98 as a total bandwidth of

a. &. +98

b. /.3 +98

c. 9 (&

d. 1 +98

#2. An input signal of 1. M98 mixed with a local oscillator of M98. A filter selects the difference signal. (he output is

a. 1. M98

b. 3.2 %(&

c. M98

d. /. M98

##. *hat is produced by oer modulation in AM

a. Sidebands

b. 0platter

c. Enelope

d. !eiation

#&. (he letter4number designation 'E is a form of modulation also +nown as

a. ilot4carrier system

b. ndependent sideand emission

c. =incompex

d. )estigial sideband transmission


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#. (he inputs to a balanced modulator are 1 M98 and a carrier of 1. M98. (he outputs are

a. -- +98

b. 2. Mh8

c. 1. M98

d. Bot$ a and

#/. A widely used balanced modulator is called the

a. !iode bridge circuit

b. $ull4wae bridge rectifier

c. attice modulator

d. 'alanced bridge modulator

#3. *hat is the third character in the emission designation for telephony

a. $

b. '

c. !

d. *

#. A 1--4M98 carrier is deiated - +98 by a &4+98 signal

a.

b.

c. 12.!

d. 2-

#. (he maximum deiation of an $M carrier is 2 +98 by a maximum modulating signal of &-- 98. (he deiation ratio is

a. -.2

b. !

c.


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d. &-

&-. (he phenomenon of a strong $M signal dominating a wea+er signal on a common frequency is referred to as the

a. apture effect

b. 'lot out

c. Buieting factor

d. !ominating syndrome

&1. "n a low4leel AM system, amplifier following the modulated stage must be

a. inear de+ices

b. 9armonic deices

c. %lass % amplifier

d. 7onlinear deices

&2. "f the carrier of a 1-- percent modulated AM wae is suppressed, the percentage power saing will be

a. -

b. 1-

c. 1--

d. --.--

. A pre4emphasis circuit proides extra noise immunity by

a. 'oosting the bass frequencies

b. Amplifying t$e $ig$er audio fre)uencies

c. re4amplifying the whole audio band

d. %onerting the phase modulation to $M

&&. Cne of the following transmits only one sideband

a. 9#E

b.


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c. 43*

d. 'E

&. DDDDD is an electronic instrument used to show both the carrier and the sidebands of a modulated signal in the

frequency domain

a. 0pectrum analy&er

b. Cscilloscope

c. !igital counter

d. $requency counter

&/. AM transmission power increases with DDDDD

a. $requency

b. Source

c. =oad

d. %odulation

&3. *hat type of emission is frequency modulation

a. 53*

b. ?#E

c. A#E

d. '#E

&. *hat is the carrier swing of an $M transmitter when modulated by 3

a. #.2 +98

b. & +98

c. /.2 +98

d. 112.! (&

&. An increase in transmitter power from 2 * to #- * will cause the antenna current to increase from 3-- mA to


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a. -- mA

b. 3- mA

c. 7-7 mA

d. &- mA

-. DDDDD is the function which tends to maintain the sound olume leel of a oice receier nearly constant for a large

signal strength range

a. Squelch

b. Muting

c. A#

d. A$%

1. An $M receier with an "4$ of 1-.3 M98 is tuned to .3 M98. *hat is the numerical alue of the image frequency

a. 33.# M98

b. .- M98

c. 1-.& M98

d. 12,.1 %(&

2. (he function which tends to silence the receier in the absence of transmitted carrier

a. 0)uelc$

b. Muting

c. A?%

d. A$%

#. (he term used to refer to the condition where the signals from a ery strong station are superimposed on othersignals being receied

a. ross6modulation interference

b. "ntermodulation interference

c.


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d. %apture effect

&. Stages that are common to both AM and $M receiers

a. (uner, local oscillator, detector, A$ amplifier

b. 5 amplifier mier 5 amplifier A5 amplifier

c. =ocal oscillator,


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a. 2- +98

b. 27, (&

c. 2- +98

d. & +98

. An amplifier operating oer the frequency range of & to &/- +98 has a 2-- +F input resistor. *hat is the

b. 17' ;

c. 1.3& >

d. 13 >

/2. *hich of the following is not a source of external noise

a. T$ermal agitation

b. Auto ignition

c. (he sun


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d. $luorescent lights

/#. *hat is the noise oltage across a #-- F input resistance to a () set with a / M98 bandwidth and temperature of

#-G%

a. 2.# 6)

b. #. 6)

c. !.! :V

d. /.& 6)

/&. "f bandwidth is doubled, the signal power is DDDDD

a. "ot c$anged

b. Buadrupled

c. (ripled

d. !oubled

/. "n an $M transmitter, what is the result of oer modulation

a. =ower frequency

b. !istortion

c. 9igher power

d. *cessi+e and


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. ', dB

c. 4&- d'm

d. &- d'm

/. "f an amplifier has equal input and output impedances, what oltage ratio does the gain of - d' represent

a. 31-.2

b. #2.2

c. #2-.1

d. #1.-

/. An interfering signal with a frequency equal to the receied signal plus twice the "$ is called

a. mage fre)uency

b. %enter frequency

c.


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d. '

32. *hat determines the selectiity of a receier

a. T$e and


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a. #. M98

b. 1,7.2 %(&

c. 112. M98

d. 1-. M98

33. A superheterodyne is tuned to 23# +98. (he "$ is &3 +98. *hat is the image frequency

a. #.- M98

b. &. +98

c. +98

d. 3-88 (&

3. "n an $M receier, which circuit remoes amplitude ariations

a. Exciter

b. Mixer

c. !iscriminator

d. imiter

3. "n an $M receier, the circuit that +eeps the receier tuned exactly to the desired station is DDDDD

a. A5

b. A?%

c. =imiter

d. !iscriminator

-. *hat connects the front4end circuit of a )9$ () superheterodyne receier

a. Mixer,


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d. =ocal oscillator, A?% and antenna

Modulation

Multiple choice. Encircle the letter which corresponds to your answer.

1 Having an information signal change some characteristic of a carrier signal is calleda Multiplexing

Modulation

c Duplexingd Linear mixing

2 Which of the following is not true about AM?

a he carrier amplitude varies!

b he carrier fre"uenc# remains constant!c The carrier fre!uency changes.

d he information signal amplitude changes the carrier amplitude!

$ he opposite of modulation isa %everse modulation

b Downward modulation

c &nmodulation

d "e#odulation

' he circuit used to produce modulation is called

a Modulator

b Demodulator

c (ariable gain amplifier d Multiplexer

) A modulator circuit performs what mathematical operation on its two inputs?a Addition

Multiplication

c Divisiond *"uare root

+ he ratio of the pea, modulating signal voltage to the pea, carrier voltage is referred to

as

a he voltage ratio

b Decibels

c The #odulation inde$d he mix factor

- .f m is greater than 1/ what happens?a 0ormal operation

b arrier drops to ero

c arrier fre"uenc# shifts

d Infor#ation signal is distorted


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3 4or ideal AM/ which of the following is true?

a m 5 6

# %

c m 7 1d m 8 1

9 he outline of the pea,s of a carrier has the shape of the modulating signal and is called

the

a race b Waveshape

c En'elope

d arrier variation16 :vermodulation occurs when

a (# ) (c b (m 7 (c

c (m 5 (cd (m 5 (c 5 6

11 he values of (max and (min as read from an AM wave on oscilloscope are 2!3 and 6!$! the

percentage of modulation is

a 16!- ; b '1!' ;

c *+., -

d 9$!$ ;

12 he new signals produced b# modulation are calleda *purious emissions

b Harmonics

c .ntermodulation productsd ideands1$ A carrier of 336 ,H is modulated b# a $!) ,H sine wave! he L*< and &*< are/

respectivel#/

a 3-$ and 33- ,H

*/,.0 and **1.0 234

c 33$!) and 3-+!) ,Hd 33- and 3-$ ,H

1' A displa# of signal amplitude versus fre"uenc# is called the

a ime domain b 4re"uenc# *pectrum

c Amplitude *pectrumd 5re!uency "o#ain

1) Most of the power in an AM signal is in the

a Carrier

b &pper sideband


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c Lower sideband

d Modulating signal

1+ An AM signal has a carrier power of ) W! the percentage of modulation is 36; the total

sideband power isa 6!3 W

., 6c 2!) W

d '!6 W1- 4or 166 ; modulation/ what percentage of power is in each sideband?

a 70 -

b $$!$ ;c )6 ;

d 166 ;

13 An AM transmitter has a percentage of modulation of 33! he carrier power is ''6 W!

he power is ''6W! he power in one sideband is

a *0 6

b 116 Wc 1-6 W

d +16 W

19 An AM transmitter antenna current is measured with no modulation and found to be 2!+

amperes! With modulation/ the current rises to 2!9 amperes! he percentage of

modulation is

a $) ;

/+ -

c '2 ;

d 39 ;

26 What is the carrier power in the problem above if the antenna resistance is -) ohms?

a 19) W b +$1 W

c 0+/ 6

d -92 W

21 .n an AM signal/ the transmitted information is contained within the

a arrier

b Modulating signal

c ideands

d =nvelope

22 An AM signal without the carrier is called a>n

a **< b (estigial sideband

c 4M signal

d "B

2$ What is the minimum AM signal needed to transmit information?

a arrier plus sidebands


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b arrier onl#

c 8ne sideand

d


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$1 An input signal of 1!3 MH is mixed with a local oscillator of ) MH! A filter selects the

difference signal! he output is

a 1!3 MH

1.7 M34

c ) MH

d +!3 MH$2 :ne t#pe of pulse communications s#stem uses pulse that appear as a group/ and which

var# in number according to the loudness of the voice! his t#pe of pulse modulation is

called

a ulse duration modulation

b ulse amplitude modulation

c


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a %ectification

b %esonance

c (ariale resistance

d Absorption

'6 he component used to produce AM at ver# high fre"uencies is a

a (aractor b hermistor

c avit# resonator

d


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d Balanced #odulator

'- he inputs to a balance modulator are 1 MH and a carrier of 1!) MH! he outputs are

a )66 ,H b 2!) MH

c 1!) MH

d Both a and '3 A widel# used balanced modulator is called the

a Diode bridge circuit

b 4ull@wave bridge rectifier

c 9attice Modulator

d


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)) An **< generator has a sideband filter centered at $!6 MH! he modulating signal is

$,H! o produce both upper and lower sidebands/ the following carrier fre"uencies must

be produceda 2!- and $!$ MH

b $!$ and $!+ MH

c 7::/ and 1++1 234d $666 and $66$ ,H

)+ .n the phasing method of **< generation/ one sideband is canceled due to

a n

a ransporter


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+$ he amount of fre"uenc# deviation from the carrier center fre"uenc# in an 4M

transmitter is proportional to what characteristic of the modulating signal?

a A#plitude

b hasec Angle

d Dut# #cle

+'


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b =ight times

c Twice

d hrice

-1 **< transmission re"uires onl# GGGGGGG of the bandwidth for a D*


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-3 .f the carrier of a 166 percent modulated AM wave is suppressed/ the percentage power

saving will be

a )6

b 1)6c 166

d ,,.,,-9 Lea,@t#pe bias is used in a plate@modulated class amplifier to

a revent tuned circuit damping


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d he carrier fre"uenc# cannot disappear

3+ he difference between phase and fre"uenc# modulation

a .s purel# theoretical because the# are the same in practice b .s too great to ma,e the two s#stems compatible

c Lies in the poorer audio response of phase modulation

d 9ies in the different definitions of the #odulation inde$3- .ndicate the false statement regarding the Armstrong modulation s#stem!

a he s#stem is basicall# phase/ not fre"uenc#/ modulation

b A4 is not needed/ as a cr#stal oscillator is usedc 4re"uenc# multiplication must be used

d E!uali4ation is unnecessary

33 An 4M signal with a modulation index mf is passed through a fre"uenc# tripler! he wave

in the output of the tripler will have a modulation index of

a mf C$ b mf c 1 #f

d 9mf 39 An 4M signal with a deviation N is passed through a mixer/ and has its fre"uenc# reduced

fivefold! he deviation in the output of the mixer is

a ) N b .ndeterminate

c NC)

d D

96 A pre@emphasis circuit provides extra noise immunit# b#

a


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c he transmitted power is more useful

d Less modulating power is re"uired

9' :ne of the following is an indirect wa# of generating 4M! his is thea %eactance 4= modulator

b (aractor diode modulator

c Ar#strong #odulatord %eactance bipolar transistor modulator

9) .ndicate the false statement regarding the advantages of **< over double@sideband/ full@

carrier AM!

a More channel space is available

Trans#itter circuits #ust e #ore stale gi'ing etter reception

c he signal is more noise resistance

d Much less power is re"uired for the same signal strength

9+ When the modulation index of an AM wave is doubled/ the antenna current is also

doubled! he AM s#stem being used is

a A13

b A)c A$O

d A$

9- .ndicate which of the following advantages of the phase cancellation method of obtaining

**< over the filter method is falsea *witching from one sideband to the other is simpler

b .t is possible to generate **< at an# re"uenc#

c **< with lower audio fre"uencies present can be generated

d There are #ore alanced #odulators therefore the carrier is suppressed

etter

93 he most commonl# used filter in **< generation are

a Mechanical b %

c Ld Low@ pass

99 .ndicate in which one of the following onl# one sideband is transmitter

a A13

b A$c A$<

d A)

166 A$A modulation is sometimes used toa Allow the receiver to have a fre"uenc# s#nthesier

i#plify the fre!uency staility prole# in receptionc %educe the power that must be transmittedd %educe the bandwidth re"uired for transmission!

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