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 : To ensure the accuracy of a transmission, what is the minimum number of times a modulating wave should be sampled in pulse modulation?
Last Answer : 2.5 times the highest modulating frequency.
Description : A 1 Mhz carrier is amplitude modulated by a pure 200-Hz audio test tone. Which of the following combinations of frequencies represent the total content of the AM signal? A. 1 MHz and 200 Hz B. 1 MHz and 1000.2 kHz C. 999.8 kHz, 1000 kHz, and 1000.2 kHz D. 999.8 kHz and 1000.2 kHz
Last Answer : C. 999.8 kHz, 1000 kHz, and 1000.2 kHz
Description : Refers to the first symbol in an emission designation with an amplitude modulated main carrier represented by letter H. A. Single sideband suppressed carrier B. Double sideband full carrier C. Independent sideband D. Double sideband
Last Answer : B. Double sideband full carrier
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 : What is the advantage of single-sideband (ssb) transmission over AM transmission?
Last Answer : The same amount of intelligence can be transmitted with one sixth of the output power with less than one-half the bandwidth.
Description : How much must the fpa plate current vary to produce 100- percent modulation in a plate modulator?
Last Answer : Between 0 and nearly two times its unmodulated value.
Description : For AM, fc =500kHz , fm = 5 kHz Determine: (i) Upper and lower sideband frequencies (ii) Bandwidth
Last Answer : Given data fc = 500KHz , fm = 5KHz USB =fc+fm USB = 500+5 =505 KHz. LSB =fc – fm LSB = 500 – 5 =495 KHz Bandwidth = 2fm . = 2* 5 =10 KHz
Description : For 100% modulation, power in each sideband is ________ of that of carrier? a) 50% b) 70% c) 60% d) 25%
Last Answer : Ans: D
Description : Type of modulation used in TV broadcast visual transmitter. A. Pulse modulation B. DSBFC C. Vestigial sideband D. SSBFC
Last Answer : C. Vestigial sideband
Description : In the designation of bandwidth and emission, what letter in the first symbol represents a double-sideband type of modulation? A. A B. B C. C D. H
Last Answer : A. A
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 : ECE Board Exam March 1996 The letter-number designation B8E is a form of modulation also known as ___________. A. pilot carrier system B. independent sideband emission C. lincomplex D. vestigial sideband transmission
Last Answer : B. independent sideband emission
Description : What, if any, noise susceptibility advantage exists for pulse-amplitude modulation over analog amplitude modulation?
Last Answer : Both are susceptible to noise and interference
Description : What is amplitude modulation?
Last Answer : Any method of modulating an electromagnetic carrier frequency by varying its amplitude in accordance with the intelligence.
Description : In an amplitude modulated waveform, the amplitude of the sideband is
Last Answer : 1/2 carrier amplitude x modulation index
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 : The third symbol in the designation of radio emission under the ITU rules refers to A. Type of the modulation of the main carrier B. Bandwidth C. Nature of the signals modulating the main carrier D. Type of information to be transmitted
Last Answer : D. Type of information to be transmitted
Description : The first symbol in the designation of radio emission under the ITU rules to A. Nature of signals modulating the main carrier B. Type of information to be transmitted C. Bandwidth D. Type of modulation of the main carrier
Last Answer : D. Type of modulation of the main carrier
Description : Compare narrow band FM with wide-band FM w.r.t. following points. (i) Modulation index (ii) Maximum deviation (iii)Range of modulating frequency (iv)Application
Last Answer : Sr. No Parameters Narrow band FM Wide band FM 1 Modulation index Less than or slightly greater than 1 Greater than 1 2 Maximum deviation ... like police wireless, ambulance etc. Entertainment broadcasting can be used for high quality music transmission
Description : The modulation index of a FM Signal having modulating frequency 2 KHz and Max deviation is 10 KHz, is: - a) 2 b) 5 c) 3 d) 4
Last Answer : The modulation index of a FM Signal having modulating frequency 2 KHz and Max deviation is 10 KHz, is: - 5
Description : One of the FM signal generator control which varies the phase of the modulating voltage applied to the oscillator of the sweep generator A. Band control B. Phase control C. Marker amplitude control D. Sweep output control
Last Answer : B. Phase control
Description : In_____ transmission, thephaseof the carrier signal is modulated to follow the changingvoltage level (amplitude) of the modulating signal. A) AM B) PM C) FM D) none of the above
Last Answer : PM
Description : In_____ transmission, the frequency of the carrier signal is modulated to follow the changing voltage level (amplitude)of the modulating signal. The peak amplitude and phase of the carrier signal remainconstant,but as ... of thecarrier changes correspondingly. A) AM B) PM C) FM D) none of the above
Last Answer : FM
Description : In_____ transmission, thecarrier signal is modulated so that its amplitude varies with the changing amplitudes of the modulating signal. A) AM B) PM C) FM D) none of the above
Last Answer : AM
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 : 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 : What is the band of frequencies called that is included between the two points at which current falls to 70 percent of its maximum value in a resonant circuit?
Last Answer : Bandwidth of the circuit
Description : What is percent of modulation?
Last Answer : The depth or degree of modulation.
Description : What is the output frequency of an upper-sideband parametric-frequency converter?
Last Answer : The sum of the input frequency and the pump frequency.
Description : What happens to an fm signal as you increase the frequency of the modulating signal?
Last Answer : Both the bandwidth and the number of significant sidebands increase.
Description : What does the simplest diode detector use to reproduce the modulating frequency?
Last Answer : The modulation envelope.
Description : . What is the function of the modulating circuit?
Last Answer : To produce an af (or video) signal that can be superimposed on the rf signal produced by the oscillator.
Description : If a modulating wave is sampled 10 times per cycle with a 5-element binary code, how many bits of information are required to transmit the signal?
Last Answer : 28. 50.
Description : At frequencies above 100 megahertz, the intrinsic (i) region causes a pin diode to act as what?
Last Answer : Variable resistance.
Description : Refers to a continuous tone generated in a local exchange terminal through a combination of two frequencies 350 Hz, and 440 Hz. A. Busy tone B. Call waiting tone C. Dial tone D. Standard tone
Last Answer : B. Call waiting tone
Description : What does the noise weighting curve shows? A. Noise signals measured with a 144 handset B. Power levels of noise found in carrier systems C. The interfering effect of other frequencies in a voice ... a reference frequency of one kilohertz D. Interfering effects of signals compared with a 3-kHz tone
Last Answer : C. The interfering effect of other frequencies in a voice channel compared with a reference frequency of one kilohertz
Description : What is the emission designation of a single sideband reduced carrier signal? A. H3E B. J3E C. R3E D. B8E
Last Answer : C. R3E
Description : A form of single sideband emission where the degree of carrier suppression enable the carrier to be reconstituted and be used for demodulation. A. Half carrier single sideband emission B. Full carrier single sideband emission C. Reduced carrier single sideband emission D. Double sideband emission
Last Answer : C. Reduced carrier single sideband emission
Description : A single sideband emission in which the degree of carrier suppression enables the carrier to be reconstituted and to be used for demodulation. A. Reduce carrier single sideband emission ... single sideband emission C. Full carrier single sideband emission D. Standard single sideband emission
Last Answer : A. Reduce carrier single sideband emission
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 : If the single-input, differential-output, differential amplifier has an output signal taken between the two output terminals, what will the peak-to-peak amplitude of this combined output be?
Last Answer : 200 millivolts. A-18. a. Differential amplifier
Description : If the carrier of a 100 percent modulation modulated AM wave is suppressed, the percentage power saving will be (A) 50.55 (B) 15.55 (C) 10.66 (D) 66.66
Last Answer : If the carrier of a 100 percent modulation modulated AM wave is suppressed, the percentage power saving will be 66.66
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 : The _____of a composite signal is the difference between the highest and the lowest frequencies contained in that signal. A) frequency B) period C) bandwidth D) amplitude
Last Answer : frequency
Description : The quality or tone of a musical sound produced by a stringed instrument depends on – (1) frequency of vibration (2) length of the strings in the instrument (3) Amplitude of vibration (4) wave form of the sound
Last Answer : (4) wave form of the sound Explanation: The timbre or quality of a sound depends on its wave form, which varies with the number of over-tones, or harmonics, that are present, their ... particular musical sound have a different sound from another, even when they have the same pitch and loudness.
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
Last Answer : A. Quantizing noise
Description : What is the period of a wave? A. The number of degrees in tone cycle B. The number of zero crossing in one cycle C. The amplitude of the wave D. The time required to complete one cycle
Last Answer : D. The time required to complete one cycle