BROADCASTING Questions and Problems

1) The color phasor has what phase for the I signal?a) 1800

b) 370

c) 900

d) 570

2) How many AM stations can be accommodated in a 150-kHz bandwidth if the highest modulating frequency is 10 kHz?a) 10b) 16c) 7d) 14

3) What is the power in each sideband for an AM signal with 80% modulation and a total power of 2500 W?a) 400 Wb) 500 Wc) 303 Wd) 250 W

4) What is the frequency swing of an FM broadcast transmitter when modulated 60%?a) 75 kHzb) 35 kHzc) 45 kHzd) 60 kHz

5) What is the sound carrier for channel 10? a) 193.25 MHzb) 197.75 MHzc) 196.83 MHzd) 192 MHz

6) What is the picture carrier frequency for channel 7? a) 174 MHzb) 179.75 MHzc) 175.25 MHzd) 178.83 MHz

7) What is the color subcarrier for channel 5?a) 76 MHzb) 76.25 MHzc) 80.83 MHzd) 81.75 MHz

8) What percentage of the VHF band does a 6-MHz bandwidth TV signal occupy?a) 22%b) 5%c) 0.5%d) 2.2%

9) The allowable deviation ratio of commercial FM broadcast.a) 25b) 15c) 5d) 75

10) The carrier swing necessary to provide 80% modulation in the FM broadcasting band is _______.a) 150 kHzb) 120 kHzc) 60 kHzd) 75 kHz

11) The power in each sideband for an AM signal with 80% modulation is 500 W. What is the carrier power?a) 3125 Wb) 3250 Wc) 3500 Wd) 3000 W

12) What is the deviation ratio for commercial FM?a) 1b) 2c) 5

d) 1013) What is the local oscillator frequency range in commercial AM

broadcast if IF is equal to 455 kHz?a) 540 to 1600 kHzb) 0 to 1600 kHzc) 955 to 2055 kHzd) 0 to 455 kHz

14) Determine the effective radiated power of 20 kW TV broadcast transmitter whose antenna has a field gain of 2.a) 40 kWb) 80 kWc) 40,000 Wd) 8,000 W

15) What is the sound carrier for channel 16?a) 493.25 MHzb) 487.75 MHzc) 486.83 MHzd) 482 MHz

16) If broadcast station is transmitting but not modulating, what is heard in a receiver tuned to its frequency?a) Carrier onlyb) Audio onlyc) nothingd) Hiss

17) The horizontal sync pulses occur once for each of the 525 lines every 1/30 seconds. What is the frequency of these pulses? (This is also the horizontal sweep rate).a) 15.75 kHzb) 17.5 Hzc) 31.5 kHzd) 35 Hz

18) 485 separate horizontal lines are traced per picture. Thus, the vertical resolution seems to be 485 lines. What is the actual resolution of a broadcast TV if 30% cannot be resolved?a) 145b) 339c) 693d) 1617

19) In a broadcast television, the horizontal trace occurs at a 15.75 kHz frequency. What is the deviation of each line?a) 0.635 msb) 0.0635 msc) 63.5 msd) 635 s

20) What is the possible increase in horizontal resolution if the video modulating signal bandwidth was increased to 5 MHz?a) 802 linesb) 267 linesc) 535 linesd) None of these

21) What is the width to height (aspect) ratio of a TV screen if 428 vertical lines conform nicely to the 339 horizontal lines?a) ½b) 2/3c) ¾d) 4/3

22) Determine the possible increase in the vertical resolution of television if the video frequency were allowed up to 5 MHz.a) 632 linesb) 420 linesc) 535 linesd) None of these

23) What is the channel number of an FM station with 88.1 MHz carrier? a) 201

BROADCASTING Questions and Problems

b) 202c) 203d) 204

24) What is the carrier frequency of an FM station with channel number of 300?a) 107.5 MHzb) 101.1 MHzc) 107.9 MHzd) 99.5 MHz

25) FM Broadcast receivers in the 88 MHz have an intermediate frequency (IF) nominally at a) 455 kHzb) 10.7 kHzc) 15 MHzd) 500 kHz

26) The AM broadcast band in the Philippines is a) 535 to 1605 kHzb) 88 MHz to 108 MHzc) 600 kHz to 1600 kHzd) 700 kHz to 1500 kHz

27) What type of modulation does the TV aural transmitter use?a) AMb) FMc) PMd) DM

28) If the final amplifier output power of a TV broadcast station is 4 kW, the antenna transmission loss is 400 watts, and the antenna power gain is 10, the effective radiated power is a) 22 kWb) 35 kWc) 30 kWd) 19 kW

29) What type of emission used in video part of television transmission?a) F5b) F3c) A5d) A3

30) What is the purpose of the blanking poles in a television receiver?a) starts the vertical oscillatorb) cuts off the cathode ray tube beam during retracec) prevents the appearance of hum bars in the pictured) triggers the horizontal oscillator

31) How wide a frequency band must the IF amplifier of an FM broadcast receiver pass?a) 130 kCb) 140 kCc) 150 kCd) 160 kC

32) What is the frequency swing of an FM broadcast transmitter modulated 80%?a) 30 kCb) 40 kCc) 50 kCd) 60 kC

33) What is the function of quartz crystal in a radio transmitter?a) to decrease intermodulationb) to stabilize frequency of the transmitting systemc) to radiate radio frequency wavesd) to amplify weak signals

34) To cut off dangerous voltages when the cabinet of a transmitter id opened, what device is used?a) interlock switchb) filter

c) automatic insulatord) steel matting

35) Transmitter maintained only for transmitting the regular programs of broadcast stations in case of failure of the main transmitter is the a) emergency transmitterb) auxiliary transmitterc) duplicate transmitterd) reserve transmitter

36) The frequency tolerance allowed in international broadcast station isa) 20Hzb) 1 kHzc) 2 kHzd) 20 kHz

37) Auxiliary transmitter of a regular broadcast station must be tested at leasta) once a dayb) once each weekc) once every three daysd) once a month

38) What do you call the device which is used to device a standard frequency of 10 kilocycles from a standard-frequency oscillator operating on 100 kilocycles?a) millivibratorb) multivibratorc) multibratord) standard vibrator

39) What is the oscillator frequency of an FM station using two doublers, one tripler, and a quadrupler, whose center frequency is 105.6 MHz?a) 6.6 MHzb) 2.2 MHzc) 6.6 kHzd) 2.2 kHz

40) The field intensity of the antenna of a broadcast station is normally measured ina) microvolts per meterb) milliamperes per meterc) microamperes per meterd) ohm per volt

41) A radio station intended for operation in a fixed location and to contact only land mobile station is calleda) land mobile stationb) base stationc) fixed stationd) coastal station

42) A station intended for operation while in motion or at an unspecified halt is calleda) land mobile stationb) base stationc) broadcast stationd) ship station

43) The radio wave propagated from high frequency broadcast station which reaches more than 4000 km is calleda) sky waveb) surface wavec) space waved) ground wave

44) What is the purpose of station call sign?a) for status symbolb) for calling the rollc) for listening purposesd) identification of station

BROADCASTING Questions and Problems

45) What is the crystal frequency in a transmitter having three doubler stages and output frequency of 8000 kHz?a) 2000 kHzb) 1000 kHzc) 4000 kHzd) 2666.67 kHz

46) Why should a transmitter be tuned initially at reduced power?a) to save powerb) to save energyc) to prevent damage to componentsd) prevent self-oscillation

47) What is the purpose of putting crystal oscillator in a constant temperature oven?a) to prolong life of crystalb) to prevent sudden voltagec) to prevent high power consumptiond) to stabilize the oscillator frequency

48) A crystal oscillator is used to generate the carrier wave in transmitter because ita) has a power outputb) has good frequency stabilityc) can be heavily loadedd) does not need a buffer stage

49) Too much loading of an oscillator may result ina) Breakdown of the transmitterb) Better frequency stabilityc) Poor frequency stabilityd) Over modulation

50) In a frequency modulated receiver, the function of the discriminator is toa) amplify audio signalsb) separate audio signal from the IFc) bypass the audio signald) eliminate the amplitude peaks present in the IF

51) In broadcast transmitters, modulation in the oscillator stage is rarely used because a) it requires a very large power to modulate the RFb) it is liable to cause frequency instabilityc) it is very hard to attain maximum fidelityd) the output carrier cannot be suppressed

52) The stability of transmitter frequency is best maintain bya) use of Colpitts oscillator at all timesb) using several frequency multiplier c) using crystal oscillator as a frequency operatord) employing two Hartley oscillators in push-pull

53) The emission symbol for television broadcast isa) A1b) A3c) A4d) A5

54) To maintain a stable frequency, crystal in the oscillator stage area) enclosed in a cool-dry placeb) enclosed in crystal ovenc) enclosed in oil-filled tanksd) enclosed in refrigerated compartment

55) A system of telecommunication set-up for the transmission of speech, or in some cases, other sounds, isa) telegraphyb) telephonyc) telemetryd) telepathy

56) The type of emission for FM stereo (multiplex) broadcasting isa) F3Eb) F8E

c) A3d) P3

57) The width of a television broadcast channel isa) 200 MHzb) 100 kHzc) 10 kHzd) 6 MHz

58) The spare radio equipment is normally termed asa) stand-by equipmentb) secondary equipmentc) emergency equipmentd) auxiliary equipment

59) In TV broadcasting in the Philippines, the aspect ratio of the picture frame isa) 4:3b) 4:1c) 2:1d) 3:1

60) The function of a quartz crystal in a radio transmitter isa) to keep the power output highb) to keep the transmitter on its assigned frequency within

the allowed frequency tolerancec) to keep the signal to noise ratio highd) to prevent self-oscillation

61) In FM transmitter the amplitude of the antenna currenta) remains essentially constant during the process of

modulationb) varies with the amplitude of the modulating signalc) varies with the frequency of the modulating signald) none of the above

62) The squelch circuit in a radio communication receiver is useda) to reduce the inherent noise developed in the receiver

during the absence of signal frequencyb) to reduce the inherent noise developed in the receiver

during the period in which signal frequency is presentc) to improve the selectivity of the receiverd) to improve the signal-to-noise ratio of the receiver

63) A ___ is essentially a frequency stabilizer. It serves as voltage amplifier stage to isolate the crystal oscillator from the radio frequency amplifier circuit.a) buffer amplifierb) IF amplifierc) RF amplifierd) Power amplifier

64) Undesired oscillations developed in a radio frequency amplifier circuit as some frequency higher than the normal operating frequency.a) thermal noiseb) shot noisec) interference signald) parasitic oscillation

65) Which of the following does not belong to the group? Some of the possible indications of a defective transmitting vacuum tube area) a gassy tube, as indicated by a blue-haze, red hot plate

and/or fluctuations in plate currentb) low emission as indicated by no reading or a low reading

on the plate-current meter accompanied by a slightly high voltage reading

c) smell of burned ceramicd) burned-out filament

66) ___ is used to load a transmitter for testing purpose without radiationa) end-fire array antennab) dummy antenna

BROADCASTING Questions and Problems

c) Discone antennad) Rhombic antenna

67) The expression “positive temperature coefficient” as applied to a quartz crystal meansa) that the frequency of the crystal does not change with the

temperatureb) that the frequency of the crystal varies directly with the

temperaturec) that the frequency of the crystal varies indirectly with the

temperatured) that the frequency of the crystal varies very little with a

change in temperature68) The expression “negative temperature coefficient” as applied to

a quartz crystal meansa) that the frequency of the crystal varies very little with a

change in temperatureb) that the frequency of the crystal varies directly with the

temperaturec) that the frequency of the crystal varies indirectly with the

temperatured) that the frequency of the crystal does not change with the

temperature69) The video signal transmitted on a TV program employs

a) pulse-code modulationb) pulse modulationc) amplitude modulationd) frequency modulation

70) The sound transmitted on a TV program employsa) pulse-code modulationb) pulsec) amplituded) frequency modulation

71) In broadcast studios, a zero VU indicates how many percent modulations?a) 25b) 50c) 70d) 100

72) This amplifier is used to isolate oscillator from power amplifiersa) audio amplifierb) high gain amplifierc) IF amplifierd) Buffer amplifier

73) A power line filter for rejecting RF interference hasa) RF coupling capacitor in series with the power lineb) RF chokes in shunt across the power linec) 60 Hz chokes in series with the power lined) RF bypass capacitors in shunt across the power line

74) In a broadcast station, the audio peak limiters are used toa) eliminate third harmonic radiation b) minimize regenerationc) prevent distortion of oscillator waveformd) prevent the modulation percentage of the transmitter to

be exceeded75) MDS means

a) Multipoint Distribution Serviceb) Multipoint digital Servicec) Maritime Data Standardsd) Multipoint Drop Standards

76) ITFS meansa) International Television Frequency Standardb) Instructional Telephone Frequency Servicec) Instructional Television Fixed Serviced) International Telecommunications Frequency Standard

77) The ultimate Dolby surround system is the

a) Dolby NRb) Dolby Prologicc) dBxd) Hall matrix

78) A ___ is equivalent to 525 scanning linesa) fieldb) framec) cycled) interface set

79) A ___ represents one set of 262 ½ scanning linesa) fieldb) framec) cycled) interface set

80) The number of scanning lines is ___ per second.a) 14750b) 15570c) 15750d) 16550

81) Picture frames are repeated at the rate of ___ per second.a) 25b) 30c) 40d) 50

82) Lack of raster is an indication of noa) AGCb) High voltagec) Video signald) Television signal

83) What is a complete raster scan of the TV screen?a) Pixelb) Resolutionc) Framed) Filed

84) An antenna that can only receive a television signal.a) Isotropic antennab) TVROc) Reference antennad) Yagi antenna

85) Which band does channel 14 of the television channel beling?a) High VHF bandb) EHF bandc) UHF bandd) Low VHF band

86) A third symbol radio that represents telephone transmission including sound broadcasting.a) Wb) Fc) Cd) E

87) TV hue is a function ofa) DC bias on picture tubeb) AC video signal amplitudec) Phase angle of 3.58 MHz signald) Amplitude of 3.58 MHz signal

88) TV brightness is a function ofa) DC bias on picture tubeb) AC video signal amplitudec) Phase angle of 3.58 MHz signald) Amplitude of 3.58 MHz signal

89) TV contrast is a function ofa) Frequency response of video signalb) AC video signal amplitudec) Phase angle of 3.58 MHz signald) Amplitude of 3.58 MHz signal

BROADCASTING Questions and Problems

90) TV resolution is a function ofa) Frequency response of video signalb) AC video signal amplitudec) Phase angle of 3.58 MHz signald) Amplitude of 3.58 MHz signal

91) In a single gun color CRT, what electron beam travels straight through the tube?a) Redb) Greenc) Blued) Yellow

92) What percentage of the primary colors used in color TV are needed to produce the brightest white?a) 30% red, 59% green, 11% blueb) 33% red, 33% green, 33% bluec) 50% red, 28% green, 22% blued) 58% red, 20% green, 22% blue

93) The process of adding chrominance and luminancea) Diplexingb) Intrerleavingc) Modulationd) Resolution

94) The frequency tolerance of an AM radio broadcast station.a) 200 Hzb) 2000 Hzc) 20 Hzd) 2 Hz

95) ___ is the transmission of sound from one room to an adjacent room, thru common walls, floors or ceilings.a) Reverberationb) Refractionc) Flanking transmissiond) Reflection

96) The frequency spectrum of the stereophonic FM signala) 67 kHzb) 59.5 to 74.5 kHzc) 19 to 38 kHzd) 23 to 53 kHz

97) In television broadcasting vivid strong colors are often referred as ___.a) saturationb) huec) chrominanced) luminance

98) What is a small system network designed to distribute direct to home TV signals throughout a single dwelling block?a) CATVb) CCTCc) SMATVd) GMATV

99) When does broadcast station conducts an equipment test?a) during day timeb) during night timec) at any timed) during experimental period

100) In TV system, black and white are complementary colors.a) trueb) falsec) either a or bd) neither a nor b

ANSWERS: (BROADCASTING)1) D 570

2) C 7Solution:

BW STN = 2 f m (max = 2(10 kHz)BW STN = 20 kHz# of STNS = BW T / BW STN

= 150 kHz / 20 kHz# = 7.5 STNS 7 STNS

3) C 303 WSolution:

P SB = P c ( m2 / 4)

Pt = Pc m2

1+ ----- 2

Pc = 2500 W / [1+ (0.82/2)] = 1893.94 WP SB = (1893.94 W) [(0.8)2 / 4]PSB = 303W

4) C 45 kHzSolution:

%m = ACTUAL. x 100 MAX

ACTUAL = 0.6 (75 kHz) = 45 kHzSWING = 45 kHz

5) B 197.75 MHzSolution:

SOUND = UL – 0.25 MHz= 198 MHz – 0.25 MHz

SOUND = 197.75 MHz 6) C 175.25 MHzSolution:

PICTURE = LL + 1.25 MHz= 174 MHz + 1.25 MHz

PICTURE = 175.25 MHz7) C 80.83 MHzSolution:

COLOR = PICTURE + 3.58 MHz = 76MHz + 1.25 MHz + 3.58 MHz

COLOR = 80.83 MHz8) D 2.2%Solution:

% oVHF = TV BW x 100 VHF BW

= 6 MHz x 100 300 MHz – 30 MHz

%oVHF = 2.2%9) C 5Solution:

D.R. = MAX / fmMAX

= 75 kHz / 15 kHz = 510) B 120 kHzSolution:

%m = ACTUAL

MAX

ACTUAL = (0.8)(75kHz)ACTUAL = 60 KHz

BROADCASTING Questions and Problems

C.S. = 2 = 2 (60 kHz)C.S. = 120kHz

11) A 3125 WSolution:

PSB = Pc (m2 / 4)500 = PC (0.82 / 4)PC = 3125 W

12) C 5Solution:

D.R. = MAX / m MAX

= 75 kHz / 15 kHzD.R. = 5

13) C 955 to 2055 kHzSolution:

F o = f s + f1

At the lower band (first station) Fs = 540 kHz

Thus: FoLB = 540 + 455 = 995 kHzAt the upper band; fs = 1600 kHzThus: foUB = 1600 + 455 = 2055 kHz

: fo ranges from 955 to 2055 kHz14) B 80 kWSolution:

ERP = (GF)2 PT

= (2)2 (20 kW) = 80 kW15) B 487.75 MHz

16 – 482 MHz17 – 488 MHzSOUND = UL – 0.25 MHz

= 488 MHz – 0.25 MHzSOUND = 487.75 MHz

16) C nothing17) A 15.75 kHzSolution:

p = 525 x 30 = 15.75 kHz18) B 339Solution:

VRa = 0.7 x 485 = 33919) B 0.0635 msSolution:

t = 1 / 15.75 kHz = 63.5 s =0.0635ms

20) C 535 linesSolution:

Increase = 53.5 s x 5 MHz x 2 = 535 lines

21) D 4/3Solution:

Aspect Ratio = 428/339 4/322) B 420 linesSolution:

Visible hor. trace line = 428 linesNew trace line x 5 MHz x 2 = 428New trace line = 42.8 s

Tot deviation of horizontal trace: = 52.8s = 42.8 s + 10 s

With 1/30 s available for full picture; 1/30s/52.8s = 632 linesAllow 32 lines for vertical release:

632 - 32 = 600Vertical Resolution = 600 x 0.7 = 420 lines23) A 201Solution:

N = 5 (fc-47.9)N = 5(88.1-47.9) = 201

24) C 107.9 MHz

Solution:fc = N/5 + 47.9fc = 300/5 + 47.9 = 107.9 MHz

25) B 10.7 MHz 26) A 535 kHz to 1605 kHz27) B FM28) B 35 kW29) C A530) B cuts off the cathode ray tube beam during retrace

31) C 150 kC32) D 60 kC33) B to stabilize frequency of the transmitting system34) A interlock switch35) B auxiliary transmitter36) C 2 kHz37) B once each week38) B multivibrator39) B 2.2 MHz40) A microvolts per meter41) B base station42) A land mobile station43) A sky wave44) D identification of station45) B 1000 kHz46) C to prevent damage to components47) D to stabilize the oscillator frequency48) B has good frequency stability49) C poor frequency stability50) B separate audio signal from the IF51) B it is liable to cause frequency instability52) C using crystal oscillator as frequency operator53) D A554) B enclosed in crystal ovens55) B telephony56) B F8E57) D 6 MHz58) D auxiliary equipment59) A 4:360) B to keep the transmitter on its assigned frequency within

the allowed frequency tolerance61) A remains essentially constant during the process of

modulation62) A to reduce the inherent noise developed in the receiver

during the absence of signal frequency63) A buffer amplifier64) D parasitic oscillation65) C smell of burned ceramic66) B dummy antenna67) B that the frequency of the crystal varies directly with the

temperature68) C that the frequency of the crystal varies indirectly with the

temperature69) C amplitude modulation70) D frequency modulation71) D 10072) D buffer amplifier73) D RF bypass capacitors in shunt across the power line74) D prevent the modulation percentage of the transmitter to

be exceeded75) A Multipoint Distribution Service76) C Instructional Television Fixed Service77) B Dolby Prologic

BROADCASTING Questions and Problems

78) B frame79) A field80) C 1575081) B 3082) B high voltage83) C Frame84) B TVRO85) C UHF band86) D E87) C phase angle of 3.58 MHz signal88) A DC bias on picture tube89) B AC video signal amplitude90) A Frequency response of video signal91) B green92) A 30% red, 59% green, 11% blue93) B interleaving94) C 20 Hz95) C Flanking transmission96) D 23 to 53 kHz97) A saturation98) C SMATV99) D during experimental period100) B false