Description : What type of modulation is used on voice and video signals? A. AM B. FM C. SSB D. QPSK
Last Answer : B. FM
Description : With which emission type is the capture-effect most pronounced? A. CW B. FM C. SSB D. AM
Description : Both frequency and phase modulation utilize ________ modulation A. Phase B. AM and FM C. Digital D. Angle
Last Answer : D. Angle
Description : Used for time division multiplexing. A. Frequency modulation B. Pulsed modulation C. SSB D. Amplitude modulation
Last Answer : B. Pulsed modulation
Description : How does a SSB transmitter output power normally expressed? A. Average power B. In terms of peak envelop power C. In terms of peak-to-peak power D. Peak power
Last Answer : B. In terms of peak envelop power
Description : Inan HFC network, the upstream data are modulated using the _______ modulation technique. A) QAM B) QPSK C) PCM D) ASK
Last Answer : QPSK
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 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 : 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 carrier swing necessary to provide 80% modulation in the FM broadcasting band is __________. A. 150 kHz B. 120 kHz C. 60 kHz D. 75 kHz
Last Answer : B. 120 kHz
Description : What is the required quality factor for an SSB filter with the following data: center frequency= 1 MHz, the desired attenuation level of the unwanted sideband= 80 dB and the separation between sidebands= 200 Hz? A. 1,250 B. 12,500 C. 125,000 D. 25,000
Last Answer : C. 125,000
Description : Which modulation technique is used by GSM? a) GMSK b) BPSK c) QPSK d) GFSK
Last Answer : a) GMSK
Description : ECE Board Exam March 1996 SSB transmission requires only ______ of the bandwidth for a DSBFC transmission. A. ¼ B. 2/3 C. ½ D. ¾
Last Answer : C. ½
Description : Digital modulation technique used in modems. A. ASK B. PSK C. FSK D. All of these
Last Answer : B. PSK
Description : Give the expression for modulation index for AM and FM.
Last Answer : 1.Modulation index for AM ma=Vm / Vc Where Vm is modulating voltage Vc is the carrier voltage 2.Modulation index for FM mf=δ /fm where δ is the deviation fm is the modulating frequency
Description : Differentiate between AM and FM on the basis of: (i) Definition (ii) Bandwidth (iii) Modulation Index (iv) Application
Last Answer : Compare AM and FM on the basis of i)Definition ii)Bandwidth iii) Wave propogation iv)Number of sidebands
Description : Compare AM with FM with respect to following points: a) Definition. b) Modulation index. c) Bandwidth. d) Side band.
Last Answer : Parameters AM FM Definition It is the process in which the amplitude of carrier signal is varied in accordance with the instantaneous value of modulating signal keeping frequency and ... frequency deviation. Side band There are two sidebands Infinite number of sideband
Description : Which does not use vertical polarization antenna? A. AM Broadcasting B. FM Broadcasting C. Mobile Communications D. Satellite Communications
Last Answer : B. FM Broadcasting
Description : Most AM broadcasts employ ___ polarization while most FM broadcasts employ ___ polarization of the radio wave. A. vertical, vertical B. vertical, horizontal C. horizontal, vertical D. horizontal, horizontal
Last Answer : B. vertical, horizontal
Description : The final amplifier of either FM or AM transmitter operates as A. Class B B. Class C C. Class A D. Class D
Last Answer : B. Class C
Description : Type of emission produced by one of the early radio transmitter in trains of damped RF ac waves where its oscillator is coupled to a long wire antenna, normally used in radio telegraph and having sidebands on its carrier. A. Digital emission B. Key emission C. Cycle emission D. Spark emission
Last Answer : D. Spark emission
Description : The antenna current is doubled when the modulation index is doubled in ______ AM system. A. A5C B. A3J C. A3 D. A3H
Last Answer : B. A3J
Description : An AM transmitter is rated 100W at 100% modulation. How much power required for the carrier? A. 33.33 W B. 66.66 W C. 83.33 W D. 100 W
Last Answer : B. 66.66 W
Description : If the modulation index of an AM wave is doubled, the antenna current is also doubled, the AM system being used is A. A5C B. A3J C. A3H D. A3
Description : 100% modulation in AM means a corresponding increase in total power by: A. 25% B. 75% C. 100% D. 50%
Last Answer : D. 50%
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 : How is the degree of modulation expressed in an fm system?
Last Answer : As the ratio of the frequency deviation to the maximum frequency deviation allowable.
Description : Define modulation index in FM. What is maximum value of deviation ratio.
Last Answer : Modulation Index of FM: It is defined as the ratio of Frequency Deviation (δ) to the modulating signal frequency (fm). (OR)
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 : Define modulation index of FM.
Last Answer : Modulation index of FM is defined as the ratio of the frequency deviation to the modulating frequency.
Description : An FM signal with modulation index mƒ is passed through a frequency tripler. The modulation index of the output signal will be (1) mƒ (2) 3mƒ (3) 9mƒ (4) 27mƒ
Last Answer : An FM signal with modulation index mƒ is passed through a frequency tripler. The modulation index of the output signal will be 3mƒ
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 : ______ polarization is employed in FM broadcasting A. Horizontal B. Vertical C. Circular D. Bidirectional
Last Answer : A. Horizontal
Description : A particular circuit that rids FM of noise A. Detector B. Discriminator C. Phase Shifter D. Limiter
Last Answer : D. Limiter
Description : What is the spectrum of stereophonic FM signal? A. 19 to 38 kHz B. 30 to 53 kHz C. 59.5 to 74.5 kHz D. 88 to 108 MHz
Last Answer : B. 30 to 53 kHz
Description : What is the channel number of an FM station with a carrier frequency of 99.5 MHz? A. 256 B. 258 C. 257 D. 259
Last Answer : B. 258
Description : What is the approximate bandwidth of an FM system with 10 kHz of modulating frequency and a 150 kHz of frequency deviation? A. 300 kHz B. 320 kHz C. 150 kHz D. 200 kHz
Last Answer : B. 320 kHz
Description : Cellular radios use FM with a maximum deviation of A. ±30 khz B. ±75 khz C. ±25 khz D. ±12 khz
Last Answer : D. ±12 khz
Description : An FM receiver whose intermediate frequency is 10.7 MHz, is experiencing image channel interference from a station transmitting on 121.1 MHz. If the local oscillator is tracking above, the receiver is tuned to A. 131.8 MHz B. 110.4 MHz C. 142.5 MHz D. 99.7 MHz
Last Answer : D. 99.7 MHz
Description : How many FM stations would be accommodated I an ordinary TV channel? A. 33 B. 30 C. 40 D. 25
Last Answer : B. 30
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 : What is a frequency discriminator? A. A circuit for filtering two closely adjacent signals B. A circuit for detecting FM signals C. An FM generator D. An automatic bandswitching circuit.
Last Answer : B. A circuit for detecting FM signals
Description : The final power amplifier in an FM transmitter usually operates class ______. A. AB B. C C. B D. A
Last Answer : B. C
Description : The allowable deviation ratio of commercial FM broadcast. A. 25 B. 15 C. 5 D. 75
Last Answer : C. 5
Description : What particular circuit that rids FM of noise? A. HPF B. Phase shifter C. Limiter D. LPF
Last Answer : C. Limiter
Description : Which of the following filters block FM radio band for TV channels (2 to 13)? A. High-pass filter B. Band reject filter C. Low-pass filter D. Band-pass filter
Last Answer : B. Band reject filter
Description : After the IF stages have been aligned, the next stage to align in FM receiver is. A. local oscillator B. limiter stage C. RF amplifier D. mixer stage
Last Answer : A. local oscillator
Description : The frequency spectrum of the stereophonic FM signal. A. 67 kHz B. 59.5 to 74.5 kHz C. 19 to 38 kHz D. 30 to 53 kHz
Last Answer : D. 30 to 53 kHz
Description : In an FM receiver, which circuit removes amplitude variations? A. Exciter B. Mixer C. Discriminator D. Limiter