Description : In amplitude modulation technique the unmodulated carrier is referred to as having ______. A. 100% modulation B. 0% modulation C. 50% modulated D. Over modulated
Last Answer : B. 0% modulation
Description : This is referred to a product of simultaneous frequency and amplitude modulation or a carrier frequency variation which produces unwanted distortion. A. Absorption modulation B. Simultaneous modulation C. Dynamic instability D. Series modulation
Last Answer : C. Dynamic instability
Description : A low frequency audible periodic variation in pitch of sound output in high fidelity sound reproduction system? A. Flutter B. Wow C. String vibration D. Radio sound
Last Answer : B. Wow
Description : A pulse modulation technique as the width of a constant amplitude pulse is varied proportional to the amplitude of the analog signal at the time the signal is sampled.
Last Answer : PWM, PLM, PDM
Description : Which of the following systems is not used in radio detection and ranging? A. Frequency shift B. Frequency modulation C. Pulse radar D. Amplitude modulation
Last Answer : D. Amplitude modulation
Description : Used for time division multiplexing. A. Frequency modulation B. Pulsed modulation C. SSB D. Amplitude modulation
Last Answer : B. Pulsed modulation
Description : A method of expressing the amplitude of complex non-periodic signals such as speech. A. Frequency B. Wavelength C. Volume D. Pitch
Last Answer : C. Volume
Description : Referred to as an average power from the radio transmitter supplied to the antenna transmission line taken during one radio frequency cycle under no modulation. A. Carrier power B. Rated power C. Peak envelop power D. Mean power
Last Answer : A. Carrier power
Description : The modulation technique used by GSM cellular system A. Phase shift keying B. Frequency shift keying C. Gaussian minimum shift keying D. QAM
Last Answer : C. Gaussian minimum shift keying
Description : In single pulse modulation of PWM inverters, third harmonic can be eliminated if pulse width is equal to (a) 30o (b) 60o (c) 120o (d) 150o
Last Answer : In single pulse modulation of PWM inverters, third harmonic can be eliminated if pulse width is equal to 120o
Description : Modulation means A. Varying of information B. Utilization of a single transmission channel to carry multiple signals C. Varying of some parameters of a carrier such as its amplitude to transmit information D. Transmit pulses in DC form on a copper wire
Last Answer : C. Varying of some parameters of a carrier such as its amplitude to transmit information
Description : If the percentage modulation of an AM amplifier is 88% and the modulating signal is 1 volt, the carrier has an amplitude of _______________. A. 1.14 volts B. 0.88 volt C. 1.88 volts D. 0.12 volt
Last Answer : A. 1.14 volts
Description : Three audio waves with 100,200 and 300 volts amplitude respectively, simultaneously modulate a 450 volts carrier. What is the total percent of modulation of the AM wave? A. 69 % B. 115.5 % C. 50% D. 83%
Last Answer : D. 83%
Description : ECE Board Exam March 1996 One type of pulse communications system uses pulse that appear as a group, and which vary in number according to the loudness of the voice. This type of ... A. pulse duration modulation B. pulse amplitude modulation C. pulse code modulation D. pulse position modulation
Last Answer : A. pulse duration modulation
Description : Digital modulation technique used in modems. A. ASK B. PSK C. FSK D. All of these
Last Answer : B. PSK
Description : Which distortion is least objectionable in case of audio amplifers? A) Phase distortion B) Frequency distortion C) Harmonic distortion D) Inter modulation distortion.
Last Answer : A) Phase distortion
Description : A body is executing simple harmonic motion of amplitude 1 cm. Its velocitywhile passing through the central point is 10 mm/sec. Its frequency will be a.2.99 rps b.2.22 rps c.1 rps d.1.59 rps e.1.77 rps
Last Answer : c. 1 rps
Description : A single degree of freedom spring-mass system is subjected to a harmonic force of constant amplitude. For an excitation frequency of √3k/m , the ratio of the amplitude of steady state response to the static deflection of the spring is __________ A. 0.2 B. 0.5 C. 0.8 D. None of the above
Last Answer : B. 0.5
Description : If frequency of excitation of a forced vibration system with negligible damping is very close to natural frequency of the system, then the system will A) Execute harmonic motion of large amplitude B) Beat with a very high peak amplitude C) Perform aperiodic motion D) None of the above
Last Answer : A) Execute harmonic motion of large amplitude
Description : If the amplitude of harmonic motion is large, its frequency A) Will always be high B) Will always be less C) Can have any value D) Will be zero
Last Answer : C) Can have any value
Description : The period of oscillation of a particle undergoing simple harmonic motion is: w) independent of the amplitude of the motion x) directly proportional to the frequency of oscillation y) independent of the frequency of oscillation z) none of the above
Last Answer : ANSWER: W -- INDEPENDENT OF THE AMPLITUDE OF THE MOTION
Description : A Hertz antenna is operating on a frequency of 2182 kHz and consists of a horizontal wire that is hanged between two towers. What is the frequency of its third harmonic? A. 727 kHz B. 6546 kHz C. 436 kHz D. 6.546 kHz
Last Answer : B. 6546 kHz
Description : The lowest frequency produced by an instrument. A. Harmonic B. Fundamental C. Midrange D. 0 Hz
Last Answer : B. Fundamental
Description : Lowest frequency produced by a musical instrument. A. Fundamental B. Midrange C. Period D. Harmonic
Last Answer : A. Fundamental
Description : In frequency modulation, amplitude of modulated wave is A. positive B. negative C. constant D. zero
Last Answer : constant
Description : Variation in amplitude or frequency of carrier wave is called A. amplitude modulation B. frequency modulation C. modulation D. bandwidth
Last Answer : modulation
Description : Bits can be sent over guided and unguided media as analog signal by ___________ a. digital modulation b. amplitude modulation c. frequency modulation d. phase modulation
Last Answer : a. digital modulation
Description : Which of the following antennas is used for testing and adjusting a transmitter for proper modulation, amplifier operation and frequency accuracy? A. Elementary B. Real C. Isotropic D. Dummy
Last Answer : D. Dummy
Description : Why are frequency modulation transmitters more efficient? A. Because their power is increased by class C amplifiers B. Because their power is increased by class A amplifiers C. Because their power is increased by class B amplifiers D. Because their power is increased by class AB amplifiers
Last Answer : A. Because their power is increased by class C amplifiers
Description : What is the deviation ratio for an FM-phone signal having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3kHz? A. 60 B. 0.16 C. 0.6 D. 1.66
Last Answer : D. 1.66
Description : What is the term used to describe a spread spectrum communications system where the center frequency if a conventional carrier is altered many time per second in accordance with a pseudo ... hopping B. Direct sequence C. Time-domain frequency modulation D. Frequency compandored spread spectrum
Last Answer : A. Frequency hopping
Description : What is meant by the term modulation index? A. The processor index. B. The ratio between the deviation of a frequency modulated signal and the modulating frequency. C. The FM signal-to-noise ratio. D. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency.
Last Answer : B. The ratio between the deviation of a frequency modulated signal and the modulating frequency.
Description : What is meant by the term deviation ratio? A. The ratio of the carrier center frequency to the audio modulating frequency B. The ratio of the highest audio modulating frequency to the ... audio modulation frequency D. The ratio of the audio modulating frequency to the center carrier frequency
Last Answer : C. The ratio of the maximum carrier frequency deviation to the highest audio modulation frequency
Description : It is an average power of a radio transmitter supplied to the antenna transmission line taken during a long sufficient interval of time and compared with the lowest frequency encountered in the modulation ... operating conditions. A. Carrier power B. Rated power C. Mean power D. Peak envelop power
Last Answer : C. Mean power
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 : Average power of a radio transmitter supplied to the antenna transmission line by a transmitter during one radio frequency cycle taken under the condition of no modulation. A. Peak envelop power B. Rated power C. Carrier power D. Mean power
Last Answer : C. Carrier power
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 : A good example of a pilot tone system used in commercial frequency modulation stations. A. FDM B. Time division C. Stereo multiplexing D. Frequency modulation
Last Answer : C. Stereo multiplexing
Description : Both frequency and phase modulation utilize ________ modulation A. Phase B. AM and FM C. Digital D. Angle
Last Answer : D. Angle
Description : Which determines the number of sideband components of FM? A. Modulation frequency B. Modulation index C. Carrier frequency D. All of these
Last Answer : B. Modulation index
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 : What is the difference between phase and frequency modulation? A. Is purely theoretical because they are the same in practice B. Lies in poorer audio response of phase modulation C. Lies in the different definitions of the modulation index D. Is too great to make two systems compatible
Last Answer : C. Lies in the different definitions of the modulation index
Description : What is the main purpose of a communications system? A. None of these B. To have a frequency assignment C. For modulation D. To provide an acceptable replica of the information at the destination
Last Answer : D. To provide an acceptable replica of the information at the destination
Description : ECE Board Exam March 1996 The modulation system used for telegraphy is A. frequency-shift keying B. two-tone modulation C. pulse-code modulation D. single-tone modulation
Last Answer : A. frequency-shift keying
Description : Loudness of sound depends on – (1) Frequency (2) Wavelength (3) Amplitude (4) Pitch
Last Answer : (3) Amplitude Explanation: Loudness depends on the amplitude of the sound wave. The larger the amplitude the more energy the sound wave contains therefore the louder the sound. The pitch of a note depends on the frequency of the source of the sound.
Description : Which among the following determines the pitch of a sound? (1) Amplitude (2) Frequency (3) Loudness (4) Wavelength
Last Answer : (2) Frequency Explanation: The pitch of a sound is determined by the frequency of vibration of the sound waves So higher the frequency the higher is the pitch.
Description : The pitch of sound depends on its – (1) Frequency (2) Intensity (3) Velocity (4) Amplitude
Last Answer : (1) Frequency Explanation: Pitch is a perceptual property that allows the ordering of sounds on a frequencyrelated scale. Pitch may be quantified as a frequency, but pitch is not a purely objective physical property; it is a subjective psychoacoustical attribute of sound.
Description : Higher the frequency greater will be ________. a)pitch b)loudness c)amplitude d)infrasound
Last Answer : a)pitch
Description : Loudness of sound depends on (1) Frequency (2) Wavelength (3) Amplitude (4) Pitch
Last Answer : Amplitude
Description : The pitch of sound depends on its (1) Frequency(2) Intensity (3) Velocity (4) Amplitude
Last Answer : Frequency