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 : At 17˚ C, the noise voltage generated by 5kΩ resistor, operating over a bandwidth of 20KHz is A. 1.3 nV B. 1.3 µV C. 1.3 pV D. 1.3 mV
Last Answer : B. 1.3 µV
Description : An amplifier operating over the frequency range of 455 to 460 kHz has a 200 kΩ input resistor. What is the RMS noise voltage at the input to this amplifier if the ambient temperature is 17˚C ? A. 40 µV B. 4.0 µV C. 400 µV
Last Answer : B. 4.0 µV
Description : 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 ... does the meter read now? A. 0.5 mV B. 0.5 µV C. 5.0 mV D. 5.0 µV
Last Answer : A. 0.5 mV
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 : 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 : 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 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
Description : If current of 20 mA is passing through op-amp and voltage drop across series resistor is 10 V then value of resistance is A. 500Ω B. 400Ω C. 300Ω D. 200Ω
Last Answer : 500Ω
Description : 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 ... under test, both working at the same temperature over the same bandwidth and fed from the same source
Last Answer : C. an unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signals
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 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. 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 : What is the characteristic impedance of a two-wire line with the following data: diameter = 0.023in., spacing =0.5 in., insulation = PE.? A. 300Ω B. 250Ω C. 305Ω D. 301Ω
Last Answer : D. 301Ω
Description : Find the load impedance that must be used to terminate RG-62A/U to avoid reflections? A. 93Ω B. 75Ω C. 50Ω D. 300Ω
Last Answer : A. 93Ω
Description : Noise can be reduced by A. widening the bandwidth B. narrowing the bandwidth C. increasing temperature D. increasing transistor current levels
Last Answer : B. narrowing the bandwidth
Description : Which does not effect noise in a channel? A. None of these B. Bandwidth C. Temperature D. Quantizing level
Last Answer : D. Quantizing level
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 : What bandwidth is needed to support a capacity of 128 kbps when the signal power to noise power ratio in decibels is 100? A. 19224 Hz B. 3853 Hz C. 19244 Hz D. 3583 Hz
Last Answer : B. 3853 Hz
Description : Emission on a frequency or frequencies immediately outside the necessary bandwidth which result from the modulation process except spurious emission. A. Radiation B. Noise C. Out of the band D. Interference
Last Answer : C. Out of the band
Description : The ratio of the level of the modulated output of a transmitter under conditions of standard test modulation to the level of the demodulated output with no modulation applied both measured with the ... . Reference audio output B. None of these C. Audio frequency response D. Residual noise level
Last Answer : D. Residual noise level
Description : Top loading is used in an antenna in order to increase its ___________. A. input capacitance B. beamwidth C. bandwidth D. effective height
Last Answer : D. effective height
Description : Convert the change of temperature from 20˚C to 30˚C to Kelvin scale. a. 10 K b. 293 K c. 303 K d. 273 K
Last Answer : 10 K
Description : A temperature instrumentation system for an engine room console consists of a resistance temperature detector (RTD), a measuring bridge circuit, and a meter (or alarm circuit).Which of the following ... is zero. D. The input voltage of the resistance bridge is the constant temperature signal.
Last Answer : Answer: C
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 : 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 : What is the maximum color TV bandwidth? A. 1.6 MHz B. 0.5 MHz C. 1.0 MHz D. 1.3 MHz
Last Answer : D. 1.3 MHz
Description : Noise at the input to the receiver can be as high as several A. microvolts B. milivolts C. volts D. kilo volts
Last Answer : A. microvolts
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 : Which of the following is not a source of industrial noise? A. Automobile ignition B. Sun C. Electric Motors D. Leakage from high voltage line
Last Answer : B. Sun
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 : Noise caused by the thermal agitation of electrons in resistance. A. All of these B. Thermal noise C. Johnson’s noise D. White noise
Last Answer : A. All of these
Description : Comment on the effect of negative feedback on the gain, input and output resistance of the feedback amplifiers.Describe the gain bandwidth product term used in this context and its importance.
Last Answer : Effect of negative feedback: 1. Gain decreases with negative feedback. 2. Input resistance increases with negative feedback. 3. Output resistance decreases with negative feedback. Explanation ... feedback bandwidth increases which means it is stable output on more range of frequency.
Description : Define input offset voltage?
Last Answer : It is defined as the voltage that must be applied between the input terminals of an op-amp to nullify the output.
Description : Define input offset voltage.
Last Answer : A small voltage applied to the input terminals to make the output voltage as zero when the two input terminals are grounded is called input offset voltage.
Description : Ho w many times bigger does the bandwidth of a fiber optic multimode have over a cable? A. 50 times bigger B. 100 times bigger C. 10 times bigger D. 5 times bigger
Last Answer : B. 100 times bigger
Description : Standard design reference for environmental noise temperature. A. 300 K B. 290 K C. 32 ˚F D. 212˚F
Last Answer : B. 290 K
Description : Reference temperature use in noise analysis A. 75 K B. 250 K C. 290 K D. 300 K
Last Answer : C. 290 K
Description : What is the reference noise temperature in degrees Celsius? A. 17 B. 273 C. 25 D. 30
Last Answer : A. 17
Description : What is the noise factor if the equivalent noise temperature is 25 K? A. 1.09 B. 0.09 C. 0.36 dBm D. 0.36
Last Answer : A. 1.09
Description : What satellite system parameter represents the quality of a satellite or an earth station receiver? A. Gain-to-Equivalent Noise Temperature Ratio (G/Te) B. Energy of Bit-to-Noise Density Ratio (Eb/No) C. Carrier-to-Noise Density Ratio (C/No) D. Bit energy
Last Answer : A. Gain-to-Equivalent Noise Temperature Ratio (G/Te)
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 : Reference noise temperature. A. 70 deg F B. 30 deg C C. 290 Kelvin D. 25 deg C
Last Answer : C. 290 Kelvin
Description : ECE Board Exam March 1996 The equivalent noise temperature of the amplifier is 25 K. What is the noise figure? A. 1.86 B. 0.1086 C. 1.086 D. 10.86
Last Answer : C. 1.086
Description : The main benefit of light-wave communications over microwaves or any other communications media is a. Lower cost b. Better security c. Wider bandwidth d. Freedom from interference
Last Answer : c. Wider bandwidth
Description : Which of the following contributes to the broadening of laser emission bandwidth? a. Doppler shift of moving atoms and molecules b. Amplification within the laser medium c. Coherence of the laser light d. Optical pumping of the laser transition
Last Answer : a. Doppler shift of moving atoms and molecules
Description : Is the width of the range of wavelengths emitted by the light source a. Bandwidth b. Chromatic Dispersion c. Spectral width d. Beamwidth
Last Answer : c. Spectral width
Description : The bandwidth of optical fiber a. 900MHz b. 900PHz c. 900THz d. 900EHz
Last Answer : c. 900THz
Description : What happens to the bandwidth of an antenna as it is shortened through the use of loading coils? A. It is increased B. It is decreased C. No change occurs D. It becomes flat
Last Answer : A. It is increased