Description : What modulation is normally used with digital data? A. AM B. FM C. SSB D. QPSK
Last Answer : D. QPSK
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 : 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 : 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 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 : 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 : 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 : 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 : 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 : What type of objects are most easily detected by an fm system?
Last Answer : Stationary.
Description : Name the modulation system in which the frequency alternates between two discrete values in response to the opening and closing of a key?
Last Answer : . Frequency-shift keying.
Description : What factor determines the difference between the transmitted frequency and the received frequency in an fm transmitter?
Last Answer : Travel time.
Description : What is the major difference between direct reproduce electronics and FM reproduce electronics?
Last Answer : FM record electronics must use a limiter and demodulator circuit (figure 5-5) to demodulate the signal intelligence from the carrier frequency.
Description : The head driver circuit of a tape recorder’s FM record electronics (figure 5-4) performs what function?
Last Answer : It amplifies the frequency-modulated output from the record oscillator and sends it to the record head.
Description : How do FM record electronics differ from AM (direct record) electronics?
Last Answer : Instead of recording the signal just as it appears at the recorder’s input, FM record electronics records a frequency-modulated carrier signal from a record oscillator (figure 5-4) onto the magnetic tape
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 is the major disadvantage of an fm signal as compared to an AM signal?
Last Answer : Wide bandpass.
Description : In an fm transmitter, when does an oscillator generate only a steady frequency?
Last Answer : When no modulation is present.
Description : Why can phase-modulated signals be detected by fm detectors?
Last Answer : Because of the incidental frequency shift that is caused while phase-shifting a carrier wave that is similar to fm modulation.
Description : What is the function of an fm detector?
Last Answer : Converting frequency variations of received fm signals to amplitude variations
Description : What is the simplest form of fm detector?
Last Answer : Slope detector.
Description : What characteristic of a varactor is used in an fm modulator?
Last Answer : Capacitance.
Description : What two values may be used to determine the bandwidth of an fm wave?
Last Answer : The number of significant sidebands and the modulating frequency.
Description : Which cavity of a three-cavity klystron causes most of the velocity modulation?
Last Answer : The middle cavity.
Description : What can be added to the basic two-cavity klystron to increase the amount of velocity modulation and the power output?
Last Answer : Intermediate cavities between the input and output cavities.
Description : What types of modulation are shipboard receive-only equipment designed to receive?
Last Answer : Fm or psk.
Description : What type of modulation do most analog fiber optic communications systems use?
Last Answer : Intensity modulation.
Description : Define modulation.
Last Answer : The process of varying one or more characteristics of an optical signal to encode and convey information.
Description : Which junction of the transistor in the common-emitter detector detects the modulation envelope?
Last Answer : Emitter-base junction
Description : Phase-shift keying is similar to what other two types of modulation?
Last Answer : Cw and frequency-shift keying.
Description : What type of modulation depends on the carrier-wave phase shift?
Last Answer : Phase.
Description : What characteristic of a carrier wave is varied in frequency modulation?
Last Answer : Instantaneous frequency.
Description : What are the two types of angle modulation?
Last Answer : Frequency and phase.
Description : What is the primary advantage of pulse-modulation systems?
Last Answer : . Low susceptibility to noise.
Description : Pulse-code modulation requires the use of approximations of value that are obtained by what process?
Last Answer : Quantization.
Description : What is pulse-frequency modulation?
Last Answer : A method of pulse modulation in which a modulating wave is used to frequency modulate a pulse-generating circuit
Description : What is the main disadvantage of pulse-position modulation?
Last Answer : It requires synchronization between the transmitter and receiver.
Description : Which edges of the pulse can be modulated in pulse duration modulation?
Last Answer : Either, or both at the same time.
Description : What characteristics of a pulse can be changed in pulse time modulation?
Last Answer : The time duration of the pulses or the time of occurrence of the pulses.
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 : 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 : What action is necessary to impress intelligence on the pulse train in pulse modulation?
Last Answer : Some characteristic of the pulses has to be varied.
Description : With a single modulating tone, what is the amplitude of the sideband frequencies at 100-percent modulation?
Last Answer : One-half the amplitude of the carrier.
Description : What is percent of modulation?
Last Answer : The depth or degree of modulation.