COMM 10 - Broadcasting and Acoustics.doc

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ANSWER KEY

1. a. b. c. d.

W hi hich be best describe th the so sound wa wave? It may be longitudinal It is always transverse It is always longitudinal All of the above

2. vacuum? a. b. c. d.

Whic Which h of the foll follow owin ing g can can not not trave ravell thr throu oug gh a

3. a. b. c. d.

Thro Throug ugh h whi whic ch me medium dium does does soun sound d tra trave vell fa fastes stestt? Air   W ater   Steel Mercury

4. a. b. c. d.

Speed that is faster than that of soun d. d. Ultrasonic Supersonic Subsonic Transonic

5. a. b. c. d.

W ha hat is the sp spee d of so sound in in air at 20°C? 1087 ft/s 1100 ft/s 1126 ft/s 200 ft/s

Electromagnetic wave Radio wave Soundwave Light wave

6. Calc Calcul ulat ate e a half alf wavel avelen engt gth h sound ound for for sound ound of  16000 Hz a. 35 ft b. 10 ft c. 0.035 ft d. 100 ft 7. is a. b. c. d.

The The lowe lowes st freq freque uenc ncy y that that a hum human an ear can hear  ear  5 Hz 20 Hz 30 Hz 20 Hz

8. Sound ound that that vibr vibra ates at freq requenc uency y too too hig high for for the human ear to hear (over 20 kHz) a. Subsonic b. Ultrasonic c. Transonic d. Stereo 9. The The fr frequ equenc ency int inter erva vall bet betw ween een tw two sou sound nds s who whos se frequency ratio is 10 a. Octave b. Half octave c. Third-octave d. Decade 10. 10. A 16 KHz KHz soun sound d is is how how many any octa octave ves s high higher er than than a 500 Hz sound a. 2 b. 5 c. 4 d. 8 11. 11. a/an a. b. c. d. 12. 12. are a. b. c. d.

Soun Sound d wave waves s comp compos osed ed of but but one one fre frequ quen ency cy is Infra sound Pure tone Structure borne Residual sound Soun Sound d wav wave e has has two two mai main n cha chara ract cter eris isti tics cs whic which h Highness and loudness Tone and loudness Pitch and loudness Rarefactions and compressions

13. 13. Whe When wav waves es bend bend away away from rom st straig aight lines ines of  travel, it is called a. Reflection b. Diffraction c. Rarefaction d. Refraction

ACOUSTICS & BROADCASTING

14. 14. The The amp ampli litu tude de of soun sound d wav waves es,, the the max maxim imum um disp displa lace ceme ment nt of  each air particle, is the property which perceive as _____ of a sound a. Pitch b. Intensity c. Loudness d. Harmonics 15. 15. a. b. c. d.

It is the the wea weake kest st soun sound d tha thatt ave avera rage ge huma human n hea heari ring ng can can dete detect ct.. SPL = 0 dB Threshold of hearing Reference pressure = 2 x 10-5N/m2 A, b, c

16. 16. What What is is a devi device ce that that is used used to meas measur ure e the the hear hearing ing sens sensit itiv ivit ity y of  of  a person? a. Audiometer  b. OTDR c. SLM d. Spectrum analyzer   17. 17. What What is the the dev devic ice e use used d in in mea measu suri ring ng soun sound d pre press ssur ure e lev level els s incorporating a microphone, amplification, filtering and a display. a. Audiometer   b. OTDR c. SLM d. Spectrum analyzer   18. 18. What What weig weight hted ed sca scale le in in a soun sound d leve levell met meter er giv gives es a rea readi ding ng that that is most closely to the response of the human ear? a. Weighted scale A b. Weighted scale B c. Weighted scale C d. Weighted scale D 19. 19. is _____. a. b. c. d.

For For airc aircra raft ft noi noise se mea measu sure reme ment nts, s, the the wei weigh ghti ting ng sca scale le that that is use used d Weighted scale A Weighted scale B Weighted scale C Weighted scale D

20. 20. a. b. c. d.

It is is th the dev devic ice e use used d to to cal calib ibrrate ate an an SLM SLM? ? Microphone Pistonphone Telephone Filter  

21. 21. received. a. b. c. d.

____ _____ _ is is the the soun sound d pow power er meas measur ured ed over over the the are area a upo upon n whi which ch is Sound pressure Sound energy Sound intensity Sound pressure level

22. 22. A mea measu sure re of the the int inten ensi sity ty of soun sound d in in com compa pari riso son n to to ano anoth ther  er  sound intensity a. Phon b. Decibel c. Pascal d. Watts 23. 23. Calc Calcul ulat ate e the the soun sound d int inten ensi sity ty leve levell in dB of a sou sound nd whos whose e intensity is 0.007 W/m2. a. 95 dB b. 91 dB c. 98 dB d. 101 dB 24. 24. What What is is the the soun sound d pre press ssur ure e lev level el for for a give given n sou sound nd whos whose e RMS RMS pressure is 200/m2? a. 200 dB b. 20 dB c. 140 dB d. 14 dB 25. 25. a. b. c. d.

What What is is the the soun sound d int inten ensi sity ty for for an an RMS RMS pres pressu sure re of 200 200 Pas Pasca cal? l? 90 W/m2 98 W/m2 108 W /m2 88 W/m2

26. 26. The The sou sound nd pre press ssur ure e lev level el is incr increas eased ed by by ___ _____ __ dB dB ifif the the pres pressu sure re is doubled. a. 3 b. 4 c. 5 d. 6

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27. The sound pressure level is increased by _____  dB if the intensity is doubled. a. 3 b. 4 c. 5 d. 6 28. If four identical sounds are added what is the increase in level in dB? a. 3 b. 4 c. 5 d. 6 29. The transmission of sound from one room to an adjacent room, via common walls, floors or ceilings. a. Flanking transmission b. Reflection c. Refraction d. Reverberation 30. _____ is the continuing presence of an audible sound after the sound source has stop. a. Flutter echo b. Sound concentration c. Sound shadow d. Reverberation 31. a. b. c. d.

Required time for any sound to decay to 60 dB Echo time Reverberation time Delay time Transient time

32. a. b. c. d.

A room containing relatively little sound absorption Dead room Anechoic room Live room Free-field

33. A room in which the walls offer essentially 100% absorption, therefore simulating free field conditions. a. Dead room b. Anechoic room c. Live room d. Closed room 34. Calculate the reverberation time of the room, which has a volume of 8700 ft3 and total sound absorption 140 sabins. a. 0.3 sec b. 3.5 sec c. 3 sec d. 0.53 sec 35. It is an audio transducer that converts acoustic pressure in air into its equivalent electrical impulses a. Loudspeaker   b. Amplifier   c. Baffle d. Microphone 36. _____ is a pressure type microphone with permanent coil as a transducing element. a. Dynamic b. Condenser   c. Magnetic d. Carbon 37. A microphone which has an internal impedance of  25 kΩ is _____ type. a. High impedance b. Low impedance c. Dynamic d. Magnetic 38. a. b. c. d.

A microphone that uses the piezoelectric effect Dynamic Condenser   Crystal Carbon

39. _____ is a type of loudspeaker driver with an effective diameter of 5 inches used at midrange audio frequency. a. Tweeter   b. Woofer   c. Mid-range d. A or C

ACOUSTICS & BROADCASTING

40. _____ is measure of how much sound is produced from the electrical signal. a. Sensitivity b. Distortion c. Efficiency d. Frequency response 41. It describes the output of a microphone over a range of  frequencies. a. Directivity b. Sensitivity c. Frequency response d. All of the above 42. A loudspeaker radiates an acoustic power of 1 mW if the electrical input is 10 W. What is its rated efficiency? a. -10 dB b. -20 dB c. -30 dB d. -40 dB 43. An amplifier can deliver 100 W to a loudspeaker. If the rated efficiency of the loudspeaker is -60 dB. What is the maximum intensity 300 ft from it? a. 10 dB b. 20 dB c. 30 dB d. 40 dB 44. a. b. c. d.

Speaker is a device that Converts sound waves into current and voltage Converts current variations into sound waves Converts electrical energy to mechanical energy Converts electrical energy to electromagnetic energy

45. The impedance of most drivers is about _____ ohms at their  resonant frequency. a. 4 b. 6 c. 8 d. 10 46. energy. a. b. c. d.

It is a transducer used to convert electrical energy to mechanical Microphone Baffle Magnetic assemble Driver 

47. It is an enclosure used to prevent front and back wave cancellation. a. Loudspeaker   b. Driver   c. Baffle d. Frame 48. A circuit that divides the frequency components into separate bands in order to have individual feeds to the different drivers. a. Suspension system b. Dividing network c. Magnet assembly d. Panel board 49. a. b. c. d.

_____ is early reflection of sound. Echo Pure sound Reverberation Intelligible sound

50. a. b. c. d.

Noise reduction system used for film sound in movie. Dolby DBx dBa dBk

51. Using a microphone at less than the recommended working distance will create a _____ which greatly increases the low frequency signals. a. Roll-off   b. Proximity effect c. Drop out d. None of the choices 52. a. b. c. d.

What is the unit of loudness? Sone Phon Decibel Mel

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ACOUSTICS & BROADCASTING

b. c. d.

HF VHF VLF

66. a. b. c. d. 67. (AM) a. b. c. d.

What does the acronym STL stand for? Station-to-link Signal-to-loss-ratio Shout-to-live Studio-to-transmitter-link One of the main considerations in the selection of antenna site is

55. What is the process of sending voice, speech, music or image intended for reception by the general public? a. Navigation b. Telephony c. Broadcasting d. Mixing

68. a. b. c. d.

One of the broadcast transmission auxiliary services is: Remote pick-up STL Commun ication, Coordination an d Con trol All of the above

56. What is the frequency tolerance for the RF carrier  in the standard AM radio broadcast band? a. Zero b. 20 Hz c. 10 Hz d. 20 KHz

69. What is the spacing between any two adjacent channels in the FM broadcast band? a. 20 KHz b. 36 KHz c. 200 KHz d. 800 KHz

57. The transmitting antenna for an AM broadcast station should have a _____ polarization. a. Vertical b. Horizontal c. Circular   d. Elliptical

70. a. b. c. d.

53. level a. b. c. d.

A unit of noisiness related to the perceived noise Noy dB Sone Phon

54. What is the loudness level of a 1KHz tone if its intensity is 1 x 10-5W/cm2? a. 100 phons b. 105 phons c. 110 phons d. 100 phons

58. The part of a broadcast day from 6 PM to 6 AM local time a. Daytime b. Nighttime c. Bed time d. Experimental period 59. The service area where the signal is not subject to fading and co-channel interference. a. Primary Service Area b. Secondary Service Area c. Intermittent Service Area d. Quarternary Service Area 60. It is a resistive load used in place of an antenna to test a transmitter under normal loaded condition without actually radiating the transmitter’s output signal. a. Auxiliary Tx b. Main Tx c. Secondary Tx d. Artificial Antenna

Conductivity of the soil Height of the terrain Elevation of the site Accessibility

The first channel in the FM BC band has a center frequency of  88 MHz 88.1 MHz 88.3 MHz 108 MHz

71. What is the radio transmission of two separate signals, left, and right, used to create a multidimensional effect on the receiver? a. SCA b. Stereo system c. Pilot transmission d. Monophonic transmission 72. The carrier frequency tolerance for FM broadcasting is _____. a. 25 kHz b. 2 kHz c. 20 kHz d. 30 kHz 73. a. b. c. d.

What is the modulation used by the stereophonic subcarrier? FM PM ISB DSB

74. a. b. c. d.

What is the pilot signal for stereo FM? 4.25 MHz 10 kHz 19 KHz 38 KHz

61. The operating power of the auxiliary transmitter  shall not be less than _____% or never greater than the authorized operating power of the main transmitter. a. 5 b. 10 c. 15 d. 20

75. With stereo FM transmission, does a monaural receiver produce all the sounds that a stereo d oes? a.  Yes b. No c. Either a or b d. Neither a or b

62. a. b. c. d.

76. a. b. c. d.

Where is de-emphasis added in a stereo FM system? Before the matrix at the TX Before the matrix at the RX After the matrix at the TX After the matrix at the RX

77. a. b. c. d.

Where is the pre-emphasis added in a stereo FM system? Before the matrix at the TX Before the matrix at the RX After the matrix at the TX After the matrix at the RX

78. a. b. c. d.

The normal frequency for an SCA subcarrier is _____ KHz. 67 76 38 19

What are the frequency limits of the MF BC band? 300-3000 kHz 3-30 MHz 535-1605 kHz 88-108 MHz

63. The center to center spacing between two adjacent stations in the Phil. AM BC band is ____. a. 9 kHz b. 200 kHz c. 36 kHz d. 800 kHz 64. How many AM stations can be accommodated in a 150-kHz bandwidth if the highest modulating frequency is 10 kHz? a. 10 b. 15 c. 7 d. 14 65. a.

Short wave broadcasting operates in what band? MF

79. A monaural FM receiver receives only the _____ signal of a stereo multiplex transmission. a. L+R b. L–R c. Both a & b

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ANSWER KEY

67 KHz

80. When fed to the stereo FM modulator, in what form are the L – R signals? a. AF b. DSBSC c. 19 kHz d. 38 kHz 81. An additional channel of multiplex information that is authorized by the FCC for stereo FM radio stations to feed services such as commercial-free programming to selected customers. a. STL b. EBS c. EIA d. SCA 82. The class of FM station, which has an authorized radiated power not exceeding 125 KW: a. Class C b. Class A c. Class D d. Class B 83. An FM broadcast station, which has an authorized transmitter power not exceeding 10 KW and ERP not exceeding 30 KW: a. Class D b. Class C c. Class A d. Class B 84. A class of FM station which is limited in antenna height of 500 ft. above average terrain a. Class D b. Class C c. Class A d. Class B 85. What type of broadcast service might have their  antennas on top of hills? a. FM b. AM c. TV d. A&C 86. stations? a. signal b. c. d.

How are guardbands allocated in commercial FM 25 kHz on either sides of the transmitting 50 kHz on each side of the carrier   75 kHz deviation 15 kHz modulation

87. How many commercial FM broadcast channels can fit into the bandwidth occupied by a commercial TV station? a. 10 b. 20 c. 30 d. 40 88. How many international commercial AM broadcast channels can fit into the bandwidth occupied by a commercial TV station? a. 100 b. 200 c. 125 d. 600 89. What kind of modulation is used for the sound portion of a commercial broadcast TV transmission? a. PM b. FM c. C3F d. AM 90. Estimate the bandwidth occupied by the sound portion of a TV transmission in US. a. 25 kHz b. 800 kHz c. 80 kHz d. 200 kHz 91. What is the main reason why television picture signal uses amplitude modulation, while voice is frequency modulated? a. Better efficiency

b. c. video d.

ACOUSTICS & BROADCASTING Eliminate attenuation of both video and audio Maintain synchronized scanning between transmit and received To minimize interference between signals at received end

92. The picture and sound carrier frequencies in a TV receiver are  _____ respectively. a. 41.25 MHz, 45.75 MHz b. 45.25 MHz, 41.75 MHz c. 41.75 MHz, 45.25 MHz d. 45.75 MHz, 41.25 MHz 93. What is the separation between visual and aural carrier in TV broadcasting? a. 1.25 MHz b. 4.5 MHz c. 5.75 MHz d. 0.25 MHz 94. What is the separation between the lower limit of a channel and the aural carrier? a. 1.25 MHz b. 4.5 MHz c. 5.75 MHz d. 0.25 MHz 95. a. b. c. d.

What is the visual carrier for channel 12? 205.25 MHz 55.25 MHz 65.75 MHz 59.75 MHz

96. a. b. c. d.

What is the aural carrier for channel 3? 61.25 MHz 55.25 MHz 65.75 MHz 59.75 MHz

97. a. b. c. d.

What is color subcarrier for channel 2? 68.83 MHz 211.25 MHz 58.83 MHz 214.83 MHz

98. If the sound carrier for UHF channel 23 is 529.75 MHz, what is the frequency of the tuner’s local oscillator, when turned to this channel? a. 571 MHz b. 511 MHz c. 498 MHz d. 500 MHz 99. What is the frequency tolerance in the color carrier of TV broadcasting? a. 2 kHz b. 20 Hz c. 10 Hz d. 1 kHz 100. What is the exact picture carrier frequency for frequency for  channel 7 offset by – 10 KHz? a 175.25 MHz b 175.26 MHz c 174 MHz d 175.24 MHz 101. a. b. c. d.

TV channels 7, 11 and 13 are known as _____. Mid band UHF Low band UHF High band VHF low band UHF

102. a. b. c. d.

What is eliminated by using interlaced scanning? Noise Excessive BW Frame Flicker 

103. What percentage of the primary colors used in color TV are needed to produce the brightest white? a. 30% red, 59% green, 11% blue b. 33% red, 33% green, 33% blue c. 50% red, 28% green, 22% blue d. 58% red, 20% green, 22% blue 104.

The color with the most luminance is Red  Yellow Green

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ACOUSTICS & BROADCASTING

Blue 105. Suppose the signal from a color camera has R=0.8, G=0.4 and B=0.2, where 1 represents the maximum signal possible. Determine the value at the luminance signal a. 0.498 b. 0.254 c. 0.1325 d. 1.4 106. In the previous problem, calculate the chrominance signal a. 0.305 b. 0.304 c. 0.498 d. 0.022 107. a. b. c. d.

The three complementary colors are: White, yellow, cyan Black, white, gray  Yellow, magenta, cyan Violet, indigo, fushcia

108. When the colors Magenta and Yellow are mixed the resultant color is: a. Red b. White c. Blue d. Green 109. Which of the following consist of two of the three primary colors in television signal? a) red, b) violet, c) yellow, and d) blue a. A and B b. B and C c. C and D d. A and D 110. The studio camera produces a luminance signal that contains information about a. The musical content b. The speech content c. The brightness of the scene d. The color content of the scene 111. Brightness variations of the picture information are in which signal? a. I b. Q c.  Y d. Z 112. Which of the following is the color video signal transmitted as amplitude modulation of the 3.58 MHz C signal with bandwidth of 0 to 1.3 MHz? a. I signal b. Q signal c. Y signal d. X signal 113. Which of the following is the color video signal transmitted as amplitude modulation of the 3.58 MHz C signal in quadrature with bandwidth of 0 to 0.5 MHz? a. I signal b. Q signal c. Y signal d. Z signal 114. The _____ affects the difference between black and white on the picture tube and controls the gain of the video amplifier  a. Brightness control b. Volume control c. Power control d. Contrast control

117. What is the difference between the sound carrier and color  subcarrier frequencies? a. 1.25 MHz b. 3.58 MHz c. 4.5 MHz d. 0.92 MHz 118. a. b. c. d.

What does aspect ratio mean? Ratio of the screen width to its height Ratio of the screen hei ght to i ts wid th Ratio of the screen dia gonal to its wid th Ratio of the screen dia gonal to its heigh t

119. a. b. c. d.

What is the aspect ratio for HDTV system? 4/3 9/7 19/6 16/9

120. a. b. c. d.

The signal that will give the exact color wavelength is _____. Hue Saturation Carrier   Monochrome

121. a. b. c. d.

Which of the following represents the intensity of a given color? Hue Saturation Carrier   Monochrome

122. The _____ ensures that the electron beam will strike the correct phosphor dot on the TV screen. a. Coating b. Aperture Mask c. Diplexer   d. Duplexer   123. a. b. c. d.

In a TV receiver, what is the horizontal signal frequency? 30 Hz 60 Hz 15750 Hz 157625 Hz

124. a. b. c. d.

In a TV receiver, what is the vertical signal frequency? 30 Hz 60 Hz 15750 Hz 157625 Hz

125. What scheme is employed to cause the electron beam in the TV receiver and the electron beam in the studio camera to track identically? a. Interlacing b. NTSC c. Interleaving d. Transmission of sync pulses 126. Equalizing pulses in TV are sent during a. Horizontal blanking b. Vertical blanking c. The serrations d. Equalizing intervals 127. What is the return of the electron beam in a CRT from right to left or from bottom to top? a. Relay b. Flyback c. Utilization d. Resolution 128. a. b. c. d.

What is the North American TV standard video? PAL SECAM NTSC FCC

115. Which of the following is not a requirement for a color TV signal? a. compatibility with b lack and white receivers b. Within 6 MHz bandwidth c. Simulate a wide variety of colors d. Functional with baron super antenna

129. What is the maximum allowable frequency deviation in the audio section of a TV signal for PAL/SECAM? a. 25 kHz b. 50 kHz c. 75 kHz d. 100 kHz

116. How many electron beams actually leave the electron gun of a single-gun color CRT? a. 1 b. 2 c. 3 d. 1/3

130. a. b. c. d.

What is the frame frequency in the US TV system? 30 Hz 60 Hz 15750 Hz 157625 Hz

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ANSWER KEY

131. What is the highest video frequency set by the FCC for commercial TV? a. 4.2 MHz b. 15 MHz c. 6 MHz d. 5.5 MHz 132. What determines the maximum number of vertical picture elements? a. Number of frames per second b. Number of lines on the screen c. Number of pixels d. Number of fields per second 133. How many horizontal lines are used to develop a TV raster? a. 615 b. 525 c. 750 d. 15750 134. a. b. c. d.

c. d.

Pixel Bits

144. a. b. c. d.

It is the quality of the TV picture after imperfections Aspect ratio Utilization ratio A1 Monochrome

145. What section of a TV receiver determines the bandwidth and produces the most signal gain? a. RF amplifier   b. Audio amplifier   c. IF amplifier  d. Tuned circuit

The channel width in the U.S. TV system is : 2 MHz 6 MHz 7 MHz 8 MHz

135. It is the popular TV camera designed with much smaller package and lower cost than its earlier designs a. Image orthicon b. Iconoscope c. Vidicon d. Plumbicon 136. In a composite video signal, what is the relationship between the amplitude of the signal and the intensity of the electron beam in the receiver picture tube? a. The greater the amplitude the darker the picture b. The lower the amplitude the darker the picture c. The greater the amplitude the lighter the picture d. No effect 137. If there are 625 lines per TV picture then the number of lines per field are: a. 1250 b. 312.5 c. 625 d. 2500 138. What is the process of placing the chrominance signal in the band space between portions of the luminance signal? a. Interlacing b. Fitting c. Sneaking d. Interleaving 139. How much time elapses between the start of one horizontal sync pulse and the next? a. 10.2 μs b. 63.5 μs c. 16.67 μs d. 100 μs 140. Which of the following frequencies is wrong? a. 15 ,750 Hz for ho rizonta l syn c an d scanning b. 60 Hz for vertical sync and scanning c. 31,500 Hz for the equalizing pulses and serrations in the vertical sync pulse d. 31,500 Hz for the vertical scanning frequency 141. tellurium a. b. c. d.

Plumbicon Vidicon Saticon Silicon Vidicon

142. a. b. c. d.

The components of composite video signal are: Chroma signal Blanking pulse Synchronizing pulse All of these

ACOUSTICS & BROADCASTING

The camera tube that uses selenium, arsenic and

143. What is the smallest amount of information that can be displayed on a television screen? a. Blip b. Burst

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