NOISE SERIES

1. What is the non-continuous noise of irregular pulses or spikes of duration with high amplitudes? A. Wander B. Jitter C. Hits D. Singing2. What theorem sets a limit on the maximum capacity of a channel with a given noise level? A. Nyquist theorem B. Hartley law C. Shannon-Hartley theorem D. Shannon theorem3. Quantizing noise occurs in A. PCM B. PLM C. PDM D. PAM4. Noise always affects the signal in a communications systems at the ________. A. transmitter B. channel C. information source D. destination5. _________ is the random and unpredictable electric signals from natural causes, both internal and external to the system. A. Interference B. Attenuation C. Distortion D. Noise

6. Noise from random acoustic or electric noise that has equal energy per cycle over a specified total frequency band. A. Gaussian noise B. Whiter noise C. Thermal noise D. All of the above7. Which causes a quantization noise in PCM system? A. Serial transmission errors B. The approximation of the quantized signal C. The synchronization between encoder and decoder D. Binary coding techniques8. A particular circuit that rids FM of noise A. Detector B. Discriminator C. Phase Shifter D. Limiter9. What is the reference noise temperature in degrees Celsius? A. 17 B. 273 C. 25 D. 3010. Unwanted radio signal on assigned frequency. A. Splatter B. RFI C. Noise D. EMI

11. What is the reliable measurement for comparing amplifier noise characteristics? A. Thermal agitation noise B. Noise factor C. Noise margin D. Signal-to-noise12. _________ is measured on a circuit when it is correctly terminated but does not have any traffic. A. White noise B. Galactic noise C. Impulse noise D. Atmospheric noise13. Which standard recommends crosstalk limits? A. CCIT G.152 B. CCIT G.150 C. CCIT G.151 D. CCIT G.16114. Which standard is utilized in intermodulation noise rates on PCM audio channels? A. CCIT Rec. G.151 B. CCIT Rec. G.172 C. CCIT Rec. G.190 D. CCIT Rec. G.19015. What is the reference frequency of CCIT phosphomeric noise measurement? A. 800 Hz B.1000 Hz C. 1500 Hz D. 3400 Hz16. Reference temperature use in noise analysis A. 75 K B. 250 K C. 290 K D. 300 K17. Which noise is produced by lighting discharges in thunderstorms? A. White noise B. Extraterrestrial noise C. Industrial noise D. Atmospheric noise18. Man-made noise is usually from _______. A. transmission over power lines and by ground wave B. sky-wave C. space-wave D. troposphere19. nif stands for A. Non-intrinsic figure B. Noise improvement factor C. Narrow intermediate frequency D. Noise interference figure20. Industrial noise frequency is between _____. A. 0 to 10 KHz B. 160 MHz to200 MHz C. 15 to 160 MHz D. 200 to 3000 MHz21. External noise fields are measured in terms of _______. A. rms values B. dc values C. average values D. peak values22. Form of interference caused by rain or dust storms. A. Precipitation static B. Shot-noise C. Galactic noise D. Impulse noise23. At 17 C, the noise voltage generated by 5k resistor, operating over a bandwidth of 20KHz is A. 1.3 nV B. 1.3 V C. 1.3 pV D. 1.3 mV 24. ________ is an electric noise produced by thermal agitation of electrons in conductor and semiconductor. A. External noise B. Internal noise C. Thermal noise D. Flicker25. Three identical circuits having 10 dB signal noise-to-noise ratio each are connected in tandem with each other, what is the overall S/N? A. 5.23 dB B. 14.77dB C. 30 dB D. 40 dB26. The noise figure of the first circuit in tandem connection is 10.5 dB while its power gain is 15, what is the over all noise figure if the second circuit has a noise figure of 11 dB? A. 11.59 dB B. 11.23 dB C. 10.79 dB D. 10.5 dB27. Is the interference coming from other communications channels? A. Jitter B. Crosstalk C. RFI D. EMI28. What is the reference noise level? A. 10 pW B. 0 dBm C. 1mW D. -90 dBm29. What is the unit of noise power of psophometer? A. pWp B. dBa C. dBm D. dBrn30. A large emission of hydrogen from the sun that affects communications. A. Solar flare B. Cosmic disturbance C. Ballistic disturbance D. Solar noise31. Atmospheric noise is known as _______noise. A. static B. cosmic C. solar D. lunar32. Standard design reference for environmental noise temperature. A. 300 K B. 290 K C. 32 F D. 212F33. Absolute temperature in Kelvin. A. C + 273 B. C + 75 C. C + 19 D. C + 29034. If bandwidth is doubled, the signal power is _________. A. not changed B. quadrupled C. tripled D. doubled35. Name one or more sources of noise bearing on electronic communications. A. Steam boiler B. Galaxies C. Internal combustion engine D. Both B and C

36. The transmitter technique adopted to reduce the noise effect of the preceding question is called A. noise masking B. anitnoise C. noise killing D. preemphasis37. Deemphasis in the receiver in effect attenuates modulating signalcomponentsand noise in what frequency range? A. dc B. low C. intermediate D. high38. Atmospheric noise or static is not a great problem A. at frequencies below 20 MHz B. at frequencies below 5 MHz C. at frequencies above 30 MHz D. at frequencies above 1 MHz39. What is the proper procedure for suppressing electrical noise in a mobile station? A. Apply shielding and filtering where necessary B. Insulate a all plain sheet metal surfaces from each other C. Apply anti-static spray liberally to all nonmetallic D.Installfiltercapacitors in series with all dc wiring40. Where is the noise generated that primarily determines the signal-to-noise ratio in a VHF (150MHz) marine-band receiver? A. Man-made noise B. In the atmosphere C. In the receiver front end D. In the ionosphere41. The difference between signal strength at a given point and a reference level is________. A. power B. dBm C. level D. ratio

42. Interfering effect of noise, C message weighted, is _________. A. dBa B. dBm C. dBmc D. dB43. F1A weighting refers to ___________. A. -90 dBm B. dBrnc0 C. dBrnc D. F1A handset44.Readinga 58 dBrnC on your Western Electric 3A test set at a +7 test point is equal to ______ dBrnc0. A. 58 B. 51 C. 65 D. 2745.Readinga 58 dBrn, at a +7 test point is equal to ________ dBa0. A. 26 B. 65 C. 51 D. 4646. Areadingof -50 dBm on the disturbing pair, and -80 on the disturbed pair equals _____ dB of crosstalk coupling. A. 20 B. 30 C. 60 D. 2547. Power is __________. A. actual amount of power reference to 1mW B. logarithmic ratio of two powers C. definite amount of energy per time period D. current flow per time period

48. 15 dBa F1A weighted, equals ___________. A. -90 dBm B. -82 dBm C. -85 dBm D. -70 dBm49. You are measuring noise in a voice channel with a Lenkurt 601A, F1A weighting network and a flat meter. Your meter reads -47dBm. What is thisreadingin dBa? A. 77 dBa B. 35 dBa C. 38 dBa D. 32 dBa50. You are measuring noise at a +3 dB level point, using the Lenkurt 601A, F1A weighting network, and a flat meter. The meterreadingis -57dBm. This is ________dBa0. A. 20 B. 15 C. 25 D. 17

51. You are measuring noise at a -6 dB level point, using the Lenkurt 601A, F1A weightingnetwork, and a flat meter. The meterreadingis -59 dBm. This is _________ dBa0. A. 24 B. 12 C. 23 D. 3252. A measurement of -75 dBm, C-message weighted, would be _________ dBrnc. A. 8 B. 7 C. 9 D. 1553. Your Western Electric 3A test set meterreadingis -23 dBm at at test point level of -8 dB. This is ______ dBrnc0. A. 75 B. 29 C. 30 D. 3154. At what power level does a 1 KHz tone cause zero interference (144 weighted)? A. 90 dB B. 90 dBm C. -90 dBm D. -90 dBm55. Reference noise is ___________. A. a 1000 Hz, -90 dBm tone B. a noise that creates the same interfering effect as a 1000Hz, -90dBm tone C. a noise that creates zero dBrn in a voice channel D. B and C above56. A practical dBrn measurement will almost always in a _______ number. A. positive B. negative C. imaginary D. fractional57. What is the reference level for noise measurement, F1A weighted? A. -90 dBm B. -82 dBm C. -67 dBm D. -85 dBm58. What is the reference tone level for dBrn? A. -90 dBm B. -82 dBm C. -67 dBm D. -85 dBm59. What is the reference tone level for dBa? A. -90 dBm B. -82 dBm C. -67 dBm D. -85 dBm60. Atmospheric noise becomes less severe at frequencies A. above 30 MHz B. below 30 MHz C. above 3000 kHz D. below 3000kHz61. Indicate the noise whosesourcesare incategorydifferent from that of the other three? A. Solar noise B. Cosmic noise C. Atmospheric noise D. Galactic noise62. Indicate the false statement. A. Industrial noise is usually of the impulse type B. Static is caused by lightning discharges in thunderstorms and other natural electric disturbances occurring in the atmosphere C. Distant stars are another source of man-made noise D. Flourescent lights are another source of man-made noise63. Which of the following is not a source of industrial noise? A. Automobile ignition B. Sun C. Electric Motors D. Leakage from high voltage line64. Indicate the false statement A. The noise generated in a resistance or the resistive component of any impedance is random. B. Random noise power is proportional to the bandwidth over which is measured C. A random voltage across the resistor does not exist D. All formula referring to random noise are applicable only to the value of such noise.65. The value of the resistor creating thermal noise is doubled. The noise power generated is therefore. A. halved B. quadrupled C. doubled D. unchanged66. Indicate the false statement. A. HF mixer are generally noisier than HF amplifiers. B. Impulse noise voltage is dependent on bandwidth C. Thermal noise is independent of the frequency at which is measured. D. Industrial noise is usually of the impulse type.67. An amplifier operating over the frequency range of 455 to 460 kHz has a 200 k input resistor. What is the RMS noise voltage at the input to this amplifier if the ambient temperature is 17C ? A. 40 V B. 4.0 V C. 400 V D. 4.0 mV68. The first stage of a two-stage amplifier has a voltage gain of 10, a 600 input resistor, a 1600 equivalent noise resistance and 27k output resistor. For the second stage, these values are 25, 81k, 19k, and 1M, respectively.Calculatethe equivalent input-noise resistance of this two stage amplifier. A. 2,518 k B. 2,518 C. 251.8 D. 12,518 69. The noise output of a resistor is amplified by a noiseless amplifier having a gain of 60 and a bandwidth of 20 kHz. A meter connected at the output of the amplifier reads 1mV RMS. If the bandwidth of the amplifier is reduced to 5kHz, its gain remaining constant, what does the meter read now? A. 0.5 mV B. 0.5 V C. 5.0 mV D. 5.0 V70. The front-end of a television receiver, having a bandwidth of 7Mhz, and operating at a temperature of 27C , consists of an amplifier having a gain of 15 followed by a mixer whose gain is 20. The amplifier has a 300 input resistor and a shot noise equivalent resistance of 500; for the mixer, these values are 2.2k and 13.5k respectively, and the load resistance of the mixer is 470 k.Calculatethe equivalent noise resistance for this television receiver. A. 8760 B. 875 C. 8.76 D. 0.876 71. One of the following is not a useful quantity for comparing the noise performance receivers. A. Input noise voltage B. Equivalent noise resistance C. Noise temperature D. Noise figure.72. Indicate the false statement. Noise figure is defined as A. the ratio of the S/N power supplied at the input terminal of a receiver or amplifier to the S/N power supplied to the output or load resistor B. noise factor expressed in decibels C. an unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signals D. S/N of an ideal system divided by S/N at the output of the receiver or amplifier under test, both working at the same temperature over the same bandwidth and fed from the same source73. Calculated the noise figure of the amplifier whose Reqequals 2518 (RT=600) if its driven by a generator whose output impedance is 50. A. 39.4 B. 3.94 C. 394 D. 0.39474.Calculatethe noise figure of the receiver whose RF amplifier has an input resistance of 1000 and an equivalent shot-noise resistance of 2000, a gain of 25 and load resistance of 125 k. Given that the bandwidth is 1.0MHz and the temperature is 20C, and that the receiver is connected to an antenna with an impedance of 75. A. 30.3 B. 3.03 C. 303 D. .30375. A receiver connected to an antenna whose resistance is 50 has an equivalent noise resistance of 30.Calculateits equivalent noise temperature if the noise figure is equal to 1.6. A. 17.4 K B. 174 K C. 1.74 K D. 17 K

76. Most internal noise comes from A. Shot noise B. Transit-time noise C. Thermal agitation D. Skin effect77. Which of the following is not a source of external noise? A. Thermal agitation B. Auto ignition C. The sun D. Fluorescent lights78. Noise can be reduced by A. widening the bandwidth B. narrowing the bandwidth C. increasing temperature D. increasing transistor current levels79. Noise at the input to the receiver can be as high as several A. microvolts B. milivolts C. volts D. kilo volts80. Which circuit contributes most of the noise in a receiver? A. IF amplifier B. Demodulator C. AF amplifier D. Mixer81. Which noise figure represents the lowest noise in receiver? A. 1.6 dB B. 2.1 dB C. 2.7 dB D. 3.4 dB

82. The transistor with the lowest noise figure in the microwaveregionis a A. MOSFET B. Dual-gate MOSFET C. JFET D. MESFET83. What is the noise voltage across a 300 input resistance to a TV set with a 6MHz bandwidth and temperature of 30C? A. 2.3 V B. 3.8 V C. 5.5 V D. 5.4 V84. Which of the following types of noise becomes of great importance at frequencies? A. Shot noise B. Random noise C. Impulse noise D. Transit-time noise85. The solar cycle repeats the period of great electrical disturbance approximately every A. 11 years B. 10 years C. 9 years D. 8 years86. The square of the thermal noise voltage generated by a resistor is proportional to A. its resistance B. its temperature C. the bandwidth over which it is measured D. All of the above87. Noise occurring in the presence of signal resulting from a mismatch between the exact value of an analog signal and the closet available quantizing step in a digital coder. A. Quantizing noise B. Thermal noise C. Impulse noise D. Crosstalk88. Noise consisting of irregular pulses of short duration and relatively high amplitude, A. Quantizing noise B. Tone interference C. Impulse noise D. Cross talk89. Noise that occurs via capacitive or inductive coupling in a cable. A. Crosstalk B. Quantizing noise C. Reference noise D. Tone interference90. Sources of impulse noise induced in communication channels. A. Erroneous digital coding bit caused by an error on a transmission facility B. Transients due to relay operation C. Crosstalk from dc signaling systems D. All of these91. Crosstalk due to incomplete suppression of sidebands or to intermodulation of two or more frequency-multiplexed channels which is unintelligible is classified as A. Impulse noise B. Thermal noise C. Quantizing noise D. Miscellaneous noise92. ___________ is device that measures the internal open circuit voltage of an equivalent noise generator having an impedance of 600 and delivering noise power to a 600 load. A. Psophometer B. Barometer C. Reflectometer D. Voltmeter93. External noise originating outside the solar system A. Cosmic noise B. Solar noise C. Thermal noise D. Lunar noise94. A noise whose source is within the solar system. A. Solar noise B. Thermal noise C. Cosmic noise D. Johnson Noise95. The total noise power present in a 1-Hz bandwidth . A. Noise density B. Noise figure C. Noise limit D. Noise intensity96. Which of the following is not a way of minimizing if not eliminating noise? A. Use redundancy B. Increase transmitted power C. Reduce signaling rate D. Increase channel bandwidth97. What is the primary cause of atmospheric noise? A. Thunderstorm B. Lightning C. Thunderstorm and lightning D. Weather condition98. What do you call the noise coming from the sun and stars? A. Black-body noise B. Space noise C. Galactic noise D. All of these99. The major cause of atmospheric or static noise are A. Thunderstorms B. Airplanes C. Meteor showers D. All of these

100. Which of the following low noise transistors is commonly used at microwave frequencies? A. MOSFET B. GASFET C. MESFET D. JFET

101. An amplifier operating over a 2 MHz bandwidth has a 80 ohms input resistance. It is operating at 27 degree Celsius, has a voltage gain of 200 and input signal of 6 microvolts rms. Calculate the output rms noise. a. 325.6 millivolts b. 0.326 millivolts c. 32.55 microvolts d. d. 0.3255 microvolts102. Man-made noise is caused by a. Lightning discharge b. Solar eruptions c. Distant stars d. Arc discharges in electrical machines103. Cosmic noise is produced by a. Lightning discharge b. Solar eruption c. Distant stars d. Industrial electrical discharges104. One of the following type of noise becomes of great importance in high frequencies. It is the a. Shot noise b. Random noise c. Impulse noise d. Transit-time noise

105. Indicate the false statement a. HF mixers are generally noisier than HF amplifiers b. Impulse noise voltage is independent of bandwidth c. Thermal noise is independent of the frequency at which it is measured d. Industrial noise is usually of the impulse type106. The value of a resistor creating noise is doubled. The noise power generated is therefore a. Halved b. Quadrupled c. Doubled d. Unchanged107. One of the following is not useful for comparing the noise performance of receivers a. Input noise voltage b. Equivalent noise resistance c. Noise temperature d. Noise figure108. Indicate the noise whose source is in a category different from that a. Solar noise b. Cosmic noise c. Atmospheric noise d. Galactic noise109. Considered as the main source of an internal noise a. Flicker b. Thermal agitation c. Device imperfection d. Temperature change110. Convert noise factor of 4.02 to equivalent noise temperature. Use 300 K for environmental temperature a. 876 K b. 900 K c. 906 K d. 875 K111. Atmospheric noise is less severe at frequencies above a. 10 GHz b. 30 MHz c. 1 GHz d. Audio level112. The most common unit of noise measurement in white noise voltage testing a. NPR b. dBrn c. dBW d. dBm113. What is the major cause of atmospheric or static noise? a. Meteor showers b. Sunspots c. Airplanes d. Thunderstorms114. Background noise is the same as the following EXCEPT a. Impulse noise b. Thermal noise c. White noise d. Gaussian noise115. Noise is caused by the thermal agitation of electrons in resistance a. White noise b. Thermal noise c. Johnsons noise d. All of these116. The unit of noise power of psophometer a. dBa b. pWp c. dBm d. dBm0

117. Extra-terrestrial noise is observable at frequencies from a. 0 to 20 KHz b. Above2 GHz c. 8 MHz to 1.43 GHz d. 5 to 8 GHz

118. What signal-to-noise ratio is required for satisfactory telephone services? a. 50 dB b. 30 dB c. 40 dB d. 20 dB119. A diodegeneratoris required to produce 12 micro V of noise in a receiver with an input impedance of 75 ohms and a noise power bandwidth of 200 KHz. Determine the current through the diode in milliamperes. a. 0.4 A b. 298 mA c. 0.35 A d. 300 mA120. The equivalent noise temperature of the amplifier is 25 K. What is the noise figure? a. 0.4 A b. 298 mA c. 0.35 A d. 300 mA121. The resistor R1 and R2 are connected in series at 300K and400 K temperature respectively. If R1 is 200 ohms and R2 is 300 ohms, find the power produced at the load (RL = 500 ohms) over a bandwidth of 100 KHz. a. 0.05 nanowatts b. 0.2 nanowatts c. 0.5 femtowatts d. 2.0 femtowatts122. The random unpredictable electric signals from natural causes, both internal and external to the system is known as a. Distortion b. Noise c. Distortion d. Interference123. Given a factor of 10, what is the noise figure in dB? a. 20 dB b. 10 dB c. 50 dB d. 40 dB124. The signal in a channel is measured to be 23 dBm while noise in the same channel is measured to be 23 dBm while noise in the same channel is measured to be 9 dBm. The signal to noise ratio therefore is a. 32 dB b. 5 dB c. -14 dB d. 14 dB125. If voltage is equal to twice itsoriginalvalue, what is its corresponding change in dB? a. 3 dB b. 6 dB c. 9 dB d. 12 dB126. NIF stand for a. Non-intrinsic noise figure b. Narrow interference figure c. Noise improvement factor d. Noise interference figure127. Two resistors rated 5 ohms and 10 ohms are connected in series and are at 27 degrees Celsius. Calculate their combined thermal noise voltage for a 10 KHz bandwidth. a. 0.05 millivolts b. 0.5 millivolts c. 0.05 microvolts d. 0.005 microvolts128. What is the reference frequency of CCITT psophometric noise measurement? a. 800 Hz b. 1500 Hz c. 3400 Hz d.1000 Hz

129. A three-stage amplifier is to have an overall noise temperature no greater than 70 K. The overall gain of the amplifier is to be at least 45 dB. The amplifier is to be built by adding a low-noise first stage with existing characteristics as follows: stage 2 has 20 dB power gain and 3 dB noise figure. Stage 3 has 15 dB power gain and 6 dB noise figure. Calculate the maximum noise figure (in dB) that the first stage can have. a. 0.267 dB b. 0.56 dB c. 1.235 dB d. 0.985 dB130. A transistor has measured S/N power of 60 at its input and 19 at its output. Determine the noise figure of the transistor. a. 5 dB b. 10 dB c. 2.5 dB d. 7.5 dB131. Which does not affect noise in a channel? a. None of these b. Bandwidth c. Temperature d. Quantizing level132. Reference noise temperature a. 70 deg F b. 30 deg C c. 290 Kelvin d. 25 deg C133. Industrial noise frequency is between a. 200 to 3000 MHz b. 15 to 160 MHz c. 0 to 10 kHz d. 20 GHz134. Noise from random acoustic or electric noise that has equal per cycle over a specified total frequency band a. Thermal noise b. White noise c. Gaussian noise d. All of these135. A transistor amplifier has a measured S/N power of 100 at its input and 20 at its output. Determine the noise figure of the transistor. a. 14 dB b.7 dB c. -6 dB d. -3 dB136. What does the noise weighing curve show? a. Noise signals measured with a 144 handsets b. Power levels of noise found in carrier systems c. The interfering effect of other frequencies in a voice channel compared with a reference frequency of one kilohertz d. Interfering effects of signals compared with a 3-KHz tone137. The signal power of the input to an amplifier 100 microW and the noise power is 1 microW. At the output, the signal power is 1 W and the noise power is 40 mW. What is the amplifier noise figure? a. -6 dB b. 9 dB c. 6 dB d. -3 dB138. In measuring noise in a voice channel at a -4 dB test point level, the meter reads -70 dBm (F1A weighted), convert thereadinginto pWp. a. 53 b. 93 c. 63 d. 83139. An amplifier with 20 dB gain is connected to another with 10 dB gain by means of a transmission line with a loss of 4 dB. If a signal with a power level of -14 dBm were applied to the system, calculate the power output. a. 14 dBm b. -12 dB c. -20 dB d. 12 dBm

140. Two resistors, R1 and R2 have temperatures of 300K and400 K, respectively. What is the noise power if the two resistors are connected in series at 10 MHz bandwidth? a. 96.6 fW b. 55.2 fW c. 41.4 fW d. 88.36 fW141. Determine the shot noise for a diode with a forward bias of 1.40 mA over an 80 kHz bandwidht. (q = 1.6x10 raised to minus 9 C) a. 6 nA b. 3 mA c. 12 nA d. 15 nA142. The total noise power present in a 1 Hz bandwidth a. Noise density b. Noise figure c. Noise limit d. Noise intensity143. An amplifier with an overall gain of 20 dB is impressed with a signal whose power level is 1 watt. Calculate the output power in dBm. a. 50 dBm b. 150 dB c. 80 dBm d. 100 dBm144. What is the effect on the signal to noise ratio of a system (in dB) if the bandwidth is doubled considering all other parameters to remain unchanged except the normal thermal noise only. The S/N will be a. Increased by a factor of 2 b. Decreased by its value c. Increased by a factor of 4 d. Decreased to its value

145. Express the ratio in decibels of noise power ratio 50 is to 10 watts. a. 7 dB b. 21 dB c. 14 dB d. 3.5 dB146. What do you call the noise coming from the sun and stars? a. Black-body noise b. Space noise c. Galactic noise d. All of these147. A satellite has a noise figure of 1.6 dB. Find its equivalent noise temperature. a. 139 K b. 192 K c. 291 K d. 129 K148. What is the primary cause of atmospheric noise? a. Thunderstorm b. Lightning c. Thunderstorm and lightning d. Weather condition149. In a microwave communications system, determine the noise power in dBm for an equivalent noise bandwidth of 10 MHz. a. -104 dBm b. -114 dBm c. -94 dBm d. -174 dBm150. The solar cycle repeats the period if great electrical disturbance approximately every a. 11 years b. 10 years c. 9 years d. 8 years

151. A current change that is equal to twice its original value will correspond to a change of a. 3 dB b. 9 dB c. 10 dB d. 6 dB152. What does a power difference of 3 dB mean? a. A loss of one third of the power b. A loss of one-half of the power c. A loss of 3 watts of power d. No significant change153. A gain of 60 dB is the same as a gain of a. 10 volts/volt b. 100 volts/volt c. 1000 volts/volt d. 10,000 volts/volt154. ______ is mathematically equal to the logarithm to the base ten of the power ratio P1 over P2. a. bel b. dB c. bel/10 d. dB/2155. Noise that is produced by the active components within thereceiver. a. Thermal b. External c. Internal d. White156. Noise due to random variation in the arrival of charge carriers at the output electrode of an active device a. Shot b. Impulse c. Thermal d. Dynamic

157. Anetworkhas a loss of 20 dB. What power ratio corresponds to this loss a. 0.01 b. 0.1 c. 10 d. 100158. Areceiverconnected to an antenna whose resistance is 60 ohms has an equivalent noise resistance of 40 ohms.Calculatethe receivers noise figure in decibels and its equivalent noise temperature. a. 1.67 & 194K b. 2.23 & 194K c. 1.67 & 174K d. 2.23 & 194K159. _____ Noise is the most prevalent noise found in urban areas and is normally caused by the arc discharge from automobile or aircraft ignition systems, induction motors, switching gears, high voltage lines and the like. a. Industrial b. Johnson c. Flicker d. Mixer160. The noise figure of a totally noiseless device is a. Unity b. Infinity c. Zero d. 100161. Indicate the noise whose source is in acategorydifferent from that of the other three. a. Solar b. Cosmic c. Atmospheric d. Galactic162. The ratio(in dB) of the power of a signal at point to the power of the same signal at the reference point. a. Transmission Level Point b. Noise Figure c. S/N Ratio d. Neper

163. Anetworkhas a power gain of 3 dB. If the input power is 100 watts, the output power is a. 50 watts b. 55 watts c. 60 watts d. 62 watts164. Which of the following types of noise becomes of great importance at high frequencies? a. Shot b. Random c. Impulse d. Transmit time165. The input current of anetworkis 190 A and the output is 1.3 A. The loss in decibels is a. 20.2 b. 21.6 c. 28.6 d. 43.3166. If anetworkconnected in series have a gain of -0.5 dB, -0.3dB, -2dB and 6.8dB, the overall gain is a. 2 dB b. 2 dB c. 4 dB d. 4 dB167. What is the gain, in dB, if the output to input ratio is 1000. a. 20 b. 30 c. 40 d. 10168. The following characteristics of noise except a. Unwanted energy b. Predictable in character c. Present in the channel d. Due to any cause169. The equivalent noise temperature of the amplifier is 25 K what is the noise figure? a. 10.86 b. 1.086 c. 0.1086 d. 1.86170. Areceiverconnected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is thereceivers noise temperature? a. 464K b. 754K c. 400K d. 174K171. A theoretical antenna has a gain of 1dB. Its gain in nepers is a. 8.686 b. 0.1151 c. 6.868 d. 0.5111172. What is the equivalent output of a circuit in dBm, if it has an output of 10 watts? a. 10 dBm b. 30 dBm c. 20 dBm d. 40 dBm173. An amplifier with an input resistance of 1000 ohms is operating over a 4 MHz bandwidth.Calculatethe rms voltage if the amplifier is operating at 27 C. a. 8.14 nV b. 8.14 uV c. 6.6 nV d. 6.6 uV

174. The value of a resistor creating thermal noise is doubled. The noise power generated is therefore a. Halved b. Quadrupled c. Doubled d. Unchanged175. One of the following is not a useful quantity for comparing the noise performance of receivers. a. Input noise voltage b. Equivalent noise resistance c. Noise temperature d. Noise figure176. Any unwanted form of energy that tends to interfere with the wanted signal is called a. Noise b. Spectrum c. Radiation d. Absorption177. The correct symbol for decibel is a. DB b. dB c. Db d. db178. _____ is the noise created outside thereceiver. a. Internal b. External c. Shot d. Industrial179. _____ is the noise created by man. a. Solar b. Industrial c. Extraterrestrial d. Galactic180. A voltage change that is equal to twice its original value correspond to a change of a. 3 dB b. 6 dB c. 9 dB d. 10 dB181. Indicate the voltage level in dB with reference to one volt. This unit is used in video or TV measurement a. dBW b. dBk c. dBm d. dBV182. which of the following is not an actual amount of power? a. dB b. dBm c. dBw d. dBk183. In noise analysis, the reference temperature is a. 75 K b. 250 K c. 290 K d. 300 K184. Noise from distant panels, stars, galaxies and other celestial objects are called a. Cosmic b. Extraterrestrial c. Galactic d. Black body185. Indicate which one of the following types of noise does not occur in transistors a. Shot noise b. Flicker noise c. Partition noise d. Resistance noise186. Which of the following is not a source of space noise a. Sun b. Star c. Lightning d. Black body187. Noise that is due to the random and rapid motion of the charge carriers inside a resistive component. a. Johnson b. Thermal Agitation c. White d. All of the above188. Indicate the false statement. The square of the thermal noise voltage generated by a resistor is proportional to a. Its resistance b. Its temperature c. Boltzmanns Constant d. The bandwidth over which it is measured189. In a communication system, noise is likely to affect the signal a. At the transmitter b. In the channel c. In theinformationsource d. At the destination190. The noise power generated by a resistor is proportional to a. Temperature b. Bandwidth c. a and b d. NOTA191. Thermal noise is also known as a. Gaussian Noise b. White Noise c. Johnson noise d. All of the above192. This type of noise has a power spectrum which decreases with increasing frequency. It is most important at low frequencies from 0 to about 100 Hz). a. Shot noise b. Flicker noise c. Diode noise d. BJT noise193. Industrial noise extends up to what frequency? a. 500 MHz b. 500 GHz c. 500 THz d. 500 KHz194. Impulse Noise is a. A function of current b. A shot duration pulse c. Dependent of frequency d. Dependent of temperature195. When the power ratio of the output to input of a circuit is 200. What is the gain in dB? a. 23 b. 46 c. 23 d. 46196. What is the reference level for random noise measurement, FIA weighted? a. 82 dBm b. 90 dBm c. 85 dBm d. 77 dBm197. A 10 dB pad has an output level of -3 dBm. The level at the input is: a. 13 dBm b. -7 dBm c. 1 dBm d. 7 dBm198. The sum of three signals of 45dBm each is ______ dBm. a. 45 b. 135 c. 20 d. 50199. It is characterized by high amplitude peaks of short duration in the total noise spectrum a. Intermodulation voice b. Impulse noise c. Dropout d. Phase hits200. Originally was determined by measuring the interfering effect of noise in a Type 144 handset. A tone of 1 kHz, having a power level of 90 dBm was selected as the reference level. a. Noise figure b. S/N ratio c. Signal Figure d. Figure of Merit

201. A power level of 50 W could be expressed as: a. 1.39 dBm b. -4.3 dBm c. 1 dBm d. -13 dBm202. If a power of 0.25 mW is launched into a fiber system with an overall loss of 15 dB the output power would be: a. 250 /W b. 31.6 W c. 7.9 W d. 15 dBm203. A system having an input power of 2 mW an output power of 0.8mW has a loss of: a. 2.98 dBm b. 3.98 dB c. 3.98 W d. 1.98 mW204. An output of -10 dB means that the power has been a. Halved in value b. Increased by a factor of 10 c. Reduced by a factor of 10 d. Doubled205. Any unwanted form of energy interfering the reception of wanted signal is called a. Noise b. Sideband c. Harmonics d. Modulation206. Is the reduction of signal amplitude as it passed over the transmissionmedium. a. Noise b. Distortion c. Attenuation d. Interference207. Signal waveform perturbation or deviation caused by imperfect response of the system to the desired signal a. Noise b. Aliasing c. Distortion d. Interference208. Signal attenuation can be corrected by a. Filtering b. Modulation c. Equalization d. Amplification209. Distortion in a waveform can be corrected by a. Filtering b. Modulation c. Equalization d. Amplification

210. Signal contamination by extraneous or external sources, such as, other transmitters, power lines, and machinery. a. Noise b. Distortion c. Harmonics d. Interference211. Man-made or industrial noise is also known as a. Noise b. Distortion c. Interference d. Thermal Noise212. The noise performance of a receiver or circuit. It is expressed as ratio of the S/N power at the output. a. Noise figure b. S/N ratio c. Signal figure d. Figure ofmerit213. Noise that is caused by natural disturbances such as lightning discharge. a. Static noise b. Space noise c. Atmospheric noise d. A or C214. Atmospheric or static noise becomes less severe at frequencies a. Below 30 KHz b. Between 30 KHz and 300 KHz c. Between 300 KHz and 30 MHz d. Above 30 MHz215. Considered as space noise or extraterrestrial noise a. Solar noise b. Cosmic noise c. Black-body noise d. All of the above216. Which statement is true a. Industrial noise is usually of impulse type b. Distant stars produce atmospheric noise c. Active switches are sources of man-made noise d. Static noise is due to lightning discharges and other natural electric disturbances occurring in the atmosphere.217. Noise performance of microwave system is usually expressed in terms of a. Noise voltage, Vn= 4KTBR b. Noise power, Pn= KTB c. Noise temperature, Te = (F 1)290 d. Noise figure, F = (S/N)I/ (S/N)o218. Which circuit contributes most to the noise at the receiver? a. RF amplifier b. Mixer c. Detector d. Local Oscillator219. Which noise figure represents the lowest noise? a. 1.5 dB b. 2.0 dB c. 3.7 dB d. 4.1 dB220. Denote the interference of noise in dB above an adjusted reference noise. The adjusted reference noise level was a 1 kHz tone, set at -85 dBm a. dBa b. dBm c. dBa0 d. pWp221. The extent of noise referred to a test tone level of zero dBm. a. dBa b. dBm c. dBa0 d. pWp

222. An amplifier operating over a 4 MHz bandwidth has a 100 input resistance and is operating at 300K. Determine the noise power generated. a. 1.656 x 10-14Watts b. 1656 nW c. 1.656 pW d. 1.656 uW223. Generally used when noise readings are measured using the C-message weighting network. The reference level was 1 kHz tone, set at -90 dBm a. dBa b. dBm c. dBaO d. dBmC224. The measurement of noise was made with a C-messagefilter, and thereadingis taken at a test point where the level is zero dBm. a. dBaO b. dBmCo c. dBa d. dBmC225. Which of the following is not an important cause of distortion in DC signaling a. line resistance b. line inductance c. line capacitance d. all of the above226. There are anumberof different sources of radio noise, the most important being a. Galactic noise b. Man-made noise c. Atmospheric noise d. All of the above227. The amount of noise power is measured using a psophometric weighting network. This unit of measurement is generally used in Europe where the standard reference tone is 800 hertz, 1 picowatt. a. dBa b. dBm c. dBaO d. pWp228. Noise produced mostly by lightning discharges in thunderstorms. a. White noise b. Industrial noise c. Atmospheric noise d. Extraterrestrial noise229. Propagation of man made noise is chiefly by a. Transmission over power lines and by ground wave b. Space wave c. Sky wave d. None of these230. A more precise evaluation of the quality of a receiver as far as noise is concerned a. S/N b. VSWR c. Noise factor d. Noise margin231. NIF stands for a. Non-intrinsic figure b. Noise interference figure c. Noise improvement factor d. Narrow intermediate frequency232. External noise fields are measured in terms of a. Dc values b. Rms values c. Peak values d. Average values233. Form of interference caused by rain, hail, snow or dust storms a. Shot noise b. Galactic noise c. Impulse noise d. Precipitation static

234. Extra-terrestrial noise is observable at frequencies from a. 0 to 20 KHz b. 8 MHz to 1.43 GHz c. 5 to 8 GHz d. 15 to 160 MHz235. Industrial noise is observable from a. 15 to 160 MHz b. 200 to 3000 MHz c. 0 to 10 kHz d. 8 Mhz to 1.43 GHz236. Noise that becomes significant at VHF range and above a. Atmospheric b. Transit-time c. Galactic d. White237. Noise figure for an amplifier with noise is always a. 0 dB b. Infinite c. Less than 1 d. Greater than 1238. The noise generated by the tube, transistor or integrated circuit in an amplifier. a. White noise b. Amplification noise c. Active noise d. Dynamic Noise239. Electrical noise inherent to a particular device, circuit or system that remains when no other signal is present. a. Shot noise b. Thermal noise c. Background noise d. Static noise240. A wideband form of impulse noise generated by the electric arc in the spark plugs of an internal combustion engine. This noise is a common problem in mobile radio system. a. Thermal noise b. Shot noise c. Amplification noise d. Ignition noise241. The amount of power in dB referred to one Kilowatt a. dBW b. dBk c. dBm d. Dbv242. Noise in any form of electromagnetic interference that can be traced to non-natural causes. a. Man-made noise b. Distortion c. External noise d. Internal noise243. The frequency range wherein noise is said to be intense. a. Noise equivalent bandwidth b. Spectral response c. Cut-off frequency d. Noise cut-off frequency244. Refers to the temperature that corresponds to the spectral energy distribution of a noise. a. Absolute temperature b. Temperature band c. Noise-equivalent temperature d. Critical temperature245. A passive circuit, usually consisting of capacitance and/or inductance, that I inserted in series with the a-c power cord of an electronic device which will allow the 60-Hz current to pass and suppressed high frequency noisecomponents. a. Noisefilter b. Noise limiter c. Noise floor d. Noise quieting246. What do you call the level of background noise, relative to some reference signal. a. Noise figure b. Minimum noise c. Reference noise d. Noise floor247. A circuit often used in radio receivers that prevents externally generated noise from exceeding amplitude. They are also called noise clippers a. Noise floor b. Noisefilter c. Noise limiter d. Noise clamper248. It is referred to as a short burst of electromagnetic energy. a. Pulse b. Noise pulse c. Spike d. Noise floor249. The reduction of internal noise level in a frequency-modulated (FM) receiver as a result of an incoming signal. a. Noise quieting b. Noise limiting c. Noise suppression d. Noise degradation250. Noise generated within electronic equipment by either passive or active components. a. Shot noise b. Thermal noise c. Circuit noise d. External noise