Description : ________ is an electric noise produced by thermal agitation of electrons in conductor and semiconductor. A. External noise B. Internal noise C. Thermal noise D. Flicker
Last Answer : C. Thermal noise
Description : Most internal noise comes from A. Shot noise B. Transit-time noise C. Thermal agitation D. Skin effect
Last Answer : C. Thermal agitation
Description : What is the reliable measurement for comparing amplifier noise characteristics? A. Thermal agitation noise B. Noise factor C. Noise margin D. Signal-to-noise
Last Answer : B. Noise factor
Description : Considered as the main source of an internal noise. A. Device imperfection B. Thermal agitation C. Temperature change D. Flicker
Last Answer : B. Thermal agitation
Description : 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 above
Last Answer : D. All of the above
Last Answer : The random motion of holes and free electrons due to thermal agitation is called Diffusion.
Description : 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 these
Last Answer : D. All of these
Description : A noise whose source is within the solar system. A. Solar noise B. Thermal noise C. Cosmic noise D. Johnson Noise
Last Answer : A. Solar noise
Description : External noise originating outside the solar system A. Cosmic noise B. Solar noise C. Thermal noise D. Lunar noise
Last Answer : A. Cosmic noise
Description : 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 noise
Last Answer : D. Miscellaneous noise
Description : 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. Crosstalk
Last Answer : A. Quantizing noise
Description : 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.
Last Answer : B. Impulse noise voltage is dependent on bandwidth
Description : The value of the resistor creating thermal noise is doubled. The noise power generated is therefore. A. halved B. quadrupled C. doubled D. unchanged
Last Answer : D. unchanged
Description : 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 above
Description : Two resistors, 20kΩ, and 50kΩ are at ambient temperature. Calculate for a bandwidth equal to 100kHz, the thermal noise voltage for the two resistors connected in parallel. A. 0.4782µV B. 4278 µV C. 4.78 µV D. 47.8 µV
Last Answer : C. 4.78 µV
Description : Background noise is the same as the C. Thermal noise D. Gaussian noise 24. ECE Board Ex
Last Answer : A. Impulse noise
Description : 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 these
Description : 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 ... another source of man-made noise D. Flourescent lights are another source of man-made noise
Last Answer : C. Distant stars are another source of man-made noise
Description : Form of interference caused by rain or dust storms. A. Precipitation static B. Shot-noise C. Galactic noise D. Impulse noise
Last Answer : A. Precipitation static
Description : What is the mixing process? A. Distortion caused by auroral propagation B. The combination of two signals to produce sum and difference frequencies. C. The elimination of noise in wideband receiver by phase differentiation D. The elimination of noise in a wideband receiver by phase comparison
Last Answer : B. The combination of two signals to produce sum and difference frequencies.
Description : Quantization noise is caused by A. binary coding techniques B. serial transmission errors C. the synchronization between encoder and decoder D. the approximation of the quantized signal
Last Answer : D. the approximation of the quantized signal
Description : What is the noise voltage across a 300Ω input resistance to a TV set with a 6MHz bandwidth and temperature of 30˚C? A. 2.3 µV B. 3.8µV C. 5.5µV D. 5.4µV
Last Answer : C. 5.5µV
Description : A receiver connected to an antenna whose resistance is 50 Ω has an equivalent noise resistance of 30Ω. Calculate its equivalent noise temperature if the noise figure is equal to 1.6. A. 17.4 K B. 174K C. 1.74K D. 17K
Last Answer : B. 174K
Description : Calculate the noise figure of the receiver whose RF amplifier has an input resistance of 1000Ω and an equivalent shot-noise resistance of 2000Ω, a gain of 25 and load resistance of 125 kΩ. Given that the bandwidth is 1. ... to an antenna with an impedance of 75Ω. A. 30.3 B. 3.03 C. 303 D. .303
Last Answer : A. 30.3
Description : 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.
Last Answer : A. Input noise voltage
Description : The front-end of a television receiver, having a bandwidth of 7Mhz, and operating at a temperature of 27˚C , consists of an amplifier having a gain of 15 followed by a mixer whose gain is 20. The ... equivalent noise resistance for this television receiver. A. 8760 Ω B. 875Ω C. 8.76Ω D. 0.876Ω
Last Answer : B. 875Ω
Description : The first stage of a two-stage amplifier has a voltage gain of 10, a 600 Ω input resistor, a 1600Ω equivalent noise resistance and 27kΩ output resistor. For the second stage, these values are 25, 81kΩ, 19kΩ, and 1MΩ, ... this two stage amplifier. A. 2,518 kΩ B. 2,518 Ω C. 251.8 Ω D. 12,518 Ω
Last Answer : B. 2,518 Ω
Description : 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 ... exist D. All formula referring to random noise are applicable only to the value of such noise.
Last Answer : C. A random voltage across the resistor does not exist
Description : ECE Board Exam March 1996 A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is the receiver’s noise temperature? A. 754 K B. 464 K C. 174 K D. 293 K
Last Answer : C. 174 K
Description : An absorption loss caused by valence electrons in the silica material from which fibers are manufactured. A. Modal dispersion B. Infrared absorption C. Ion resonance absorption D. Ultraviolet absorption
Last Answer : D. Ultraviolet absorption
Description : Which noise is produced by lighting discharges in thunderstorms? A. White noise B. Extraterrestrial noise C. Industrial noise D. Atmospheric noise
Last Answer : D. Atmospheric noise
Description : _________ 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 noise
Last Answer : A. White noise
Description : One of the following is not among the advantages of series modulation A. No transformer B. Suppressed white noise C. Simple D. Modulates any frequency
Last Answer : B. Suppressed white noise
Description : The most common unit of noise measurement in white noise voltage testing. A. NPR B. dBm C. dBW D. dBrn
Last Answer : A. NPR
Description : The most common unit of noise measurement in white noise testing. A. dBw B. dBk C. dBm D. NPR
Last Answer : D. NPR
Description : Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid. (A) Viscosity (B) Thermal conductivity (C) Surface tension (D) Density
Last Answer : (D) Density
Description : Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low ... Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers
Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension
Description : As the thermal noise get doubled due to the increase in a resistance the noise power get. (A) doubled (B) quadruped (C) unchanged (D) halved.
Last Answer : As the thermal noise get doubled due to the increase in a resistance the noise power get. unchanged
Description : Stacking antenna elements A. increases sensitivity to weak signals B. will suppress odd harmonics C. decrease signal to noise ratio D. increases selectivity
Last Answer : A. increases sensitivity to weak signals
Description : Strong interference from one particular station can be eliminated by the use of A. noise limiters B. squelch circuits C. negative feedback D. wave traps in the antenna circuitry
Last Answer : D. wave traps in the antenna circuitry
Description : Which of the following low noise transistors is commonly used at microwave frequencies? A. MOSFET B. GASFET C. MESFET D. JFET
Last Answer : C. MESFET
Description : The major cause of atmospheric or static noise are A. Thunderstorms B. Airplanes C. Meteor showers D. All of these
Last Answer : A. Thunderstorms
Description : 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 these
Last Answer : B. Space noise
Description : What is the primary cause of atmospheric noise? A. Thunderstorm B. Lightning C. Thunderstorm and lightning D. Weather condition
Last Answer : B. Lightning
Description : 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 bandwidth
Last Answer : D. Increase channel bandwidth
Description : The total noise power present in a 1-Hz bandwidth . A. Noise density B. Noise figure C. Noise limit D. Noise intensity
Last Answer : A. Noise density
Description : ___________ is device that measures the internal open circuit voltage of an equivalent noise generator having an impedance of 600Ω and delivering noise power to a 600 Ω load. A. Psophometer B. Barometer C. Reflectometer D. Voltmeter
Last Answer : A. Psophometer
Description : Noise that occurs via capacitive or inductive coupling in a cable. A. Crosstalk B. Quantizing noise C. Reference noise D. Tone interference
Last Answer : A. Crosstalk
Description : Noise consisting of irregular pulses of short duration and relatively high amplitude, A. Quantizing noise B. Tone interference C. Impulse noise D. Cross talk
Last Answer : C. Impulse noise