Description : Quadrature amplitude modulation(QAM) isa combination of ___________. A) ASK and FSK B) ASK and PSK C) PSK and FSK D) none of the above
Last Answer : ASK and PSK
Description : Inan HFC network, the downstream data are modulated using the _______ modulation technique. A) PSK B) QAM C) PCM D) ASK
Last Answer : QAM
Description : _______ uses twocarriers, onein-phase andthe otherquadrature. A) ASK B) PSK C) FSK D) QAM
Description : Modulation in which no signal is present between pulses A. Pulse modulation B. QAM C. PSK D. FSK
Last Answer : A. Pulse modulation
Description : In_________, the frequencyof the carrier signal is varied to representdata. Both peak amplitudeand phase remain constant. A) ASK B) PSK C) FSK D) QAM
Last Answer : FSK
Description : In________, the amplitude of the carrier signal is varied to create signal elements. Both frequency and phase remainconstant. A) ASK B) PSK C) FSK D) QAM
Last Answer : ASK
Description : ASK, PSK, FSK,and QAM are examples of________conversion. A) digital-to-digital B) digital-to-analog C) analog-to-analog D) analog-to-digital
Last Answer : digital-to-analog
Description : Digital modulation technique used in modems. A. ASK B. PSK C. FSK D. All of these
Last Answer : B. PSK
Description : The _______ technique uses M different carrier frequencies that are modulated by the source signal. At one moment, the sign modulates one carrier frequency; at the next moment, thesignal modulates another carrier frequency. A) FDM B) DSSS C) FHSS D) TDM
Last Answer : FHSS
Description : The sinusoidal carrier is pulsed so that one of the binary states is represented by a carrier while the other is represented by its absence. A. FSK B. ASK C. PSK D. QAM
Last Answer : B. ASK
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 : An ______signal is the optical modulation of an STS-n (or STM-n) signal. A) OC-n B) TDM-n C) FDM-n D) none of the above
Last Answer : TDM-n
Description : The ______ technique expands the bandwidthof a signal by replacing each data bit with n bits. A) FDM B) DSSS C) FHSS D) TDM
Last Answer : DSSS
Description : _____ isa digital multiplexing technique for combiningseveral low-ratechannels into onehigh-rate one. A) FDM B) TDM C) WDM D) None of the above
Last Answer : TDM
Description : _____ isan analog multiplexing technique to combine optical signals. A) FDM B) TDM C) WDM D) None of the above
Last Answer : WDM
Description : Which multiplexing technique involves signals composed of light beams? A) FDM B) TDM C) WDM D) none of the above
Description : Which multiplexing technique shifts each signal to a different carrier frequency? A) FDM B) TDM C) Both (a)and (b) D) None of the above
Last Answer : FDM
Description : Which multiplexing technique transmits digital signals? A) FDM B) TDM C) WDM D) None of the above
Description : Which multiplexing technique transmits analog signals? A) FDM B) TDM C) WDM D) (a) and (c)
Last Answer : (a) and (c)
Description : In_______, the peakamplitude of one signal level is 0; the other is thesame as the amplitude of the carrier frequency. A) PSK B) OOK C) FSK D) none of the above
Last Answer : OOK
Description : Which of the following is not a digital-to-analogconversion? A) ASK B) PSK C) FSK D) AM
Last Answer : AM
Description : We candivide ____ into two different schemes: synchronousor statistical. A) FDM B) TDM C) WDM D) none of the above
Description : _____ isa digitalprocess that allows several connections to share thehighbandwidth ofa link. A) FDM B) TDM C) WDM D) None of the above
Description : ____ is designed to use thehigh bandwidthcapabilityof fiber-optic cable. A) FDM B) TDM C) WDM D) None of the above
Description : If digitaldata rateof 9600 bps is encoded using 8-level phaseshift keying (PSK) method, the modulation rate is A. 1200 bands B. 3200 bands C. 4800 bands D. 9600 bands E. None of the above
Last Answer : 3200 bands
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 : IS-95 uses which modulation technique? a) GMSK b) BPSK c) QAM d) AFSK
Last Answer : b) BPSK
Description : Which of the following is oldest multiplexing scheme? A. Frequency Division Multiplexing (FDM) B. Time Division Multiplexing (TDM) C. Code Division Multiplexing (CDM) D. Space Division Multiplexing (SDM)
Last Answer : D. Space Division Multiplexing (SDM)
Description : Multiplexing scheme use by baseband transmission. A. FDM B. Space multiplexing C. TDM D. Statistical multiplexing
Last Answer : C. TDM
Description : One of the reasons why FDM is being replaced by TDM is A. noise is amplified with voice when an FDM system is used B. it is difficult to place channels side by side C. there is more time than frequency D. Most available frequencies has been used
Last Answer : A. noise is amplified with voice when an FDM system is used
Description : Using_________each connected device is assigned a time slot whether or not the device has any thing to send. (A) WDM (B) FDM (C) TDM (D) STDM
Last Answer : (C) TDM
Description : Time synchronization is necessary in (A) FDM. (B) TDM. (C) WDM. (D) Quadrature multiplexing
Last Answer : (B) TDM.
Description : Compare FDM & TDM systems
Last Answer : Sr. No. FDM TDM 1 Divides the channel into the two or more frequency ranges that do not overlap. Divides and allocates certain Time periods to each channel. 2 Code word is ... Needs guard bands Needs guard time 4 Problem of crosstalk No problem of crosstalk
Description : In synchronous TDM, forn signal sources of the same data rate, eachframe contains _______ slots. A) n B) n + 1 C) n- 1 D) 0to n
Last Answer : n
Description : SONET is a _______ TDM system. A) asynchronous B) synchronous C) statistical D) none of the above
Last Answer : none of the above
Description : Write the expression for FSK modulation.
Last Answer : Pvf=f2-f1/k0
Description : Define FSK modulation.
Last Answer : FSK is a type of frequency modulation ,in which the binary data or code is transmitted by means of a carrier frequency that is shifted between two fixed frequency namely mark(logic1) and space frequency(logic 0).
Description : Compare binary ASK, FSK &PSK modulation techniquesÂ
Last Answer : Sr. No Parameter Binary ASK Binary FSK Binary PSK 1 Variable Characteristic Amplitude Frequency Phase 2 Maximum bandwidth(Hz) 2fb 5 fb /3 2fb 3 ... 1200 bits/sec Suitable for high bit rates 8 Detection method Envelope Envelope Coherent
Description : If the bit rate for an FSK signal is1200 bps, thebaud rate is ________. A) 300 B) 400 C) 600 D) 1200
Last Answer : 1200
Description : The constellation diagram of16-QAM has ______ dots. A) 4 B) 16 C) 8 D) none of the above
Last Answer : 16
Description : Which of the following is not an analog-to-analog conversion? A) AM B) PM C) FM D) QAM
Description : In________, the phase of thecarrier is varied to represent two or more different signal elements. Both peak amplitude and frequency remain constant. A) ASK B) PSK C) FSK D) QAM
Last Answer : PSK
Description : If the baudrate fora 64-QAM signal is 2000, what is the bit rate? A) 300 B) 400 C) 1000 D) 12000
Last Answer : 12000
Description : If the bit rate for a16-QAM signal is 4000 bps, what is the baudrate? A) 300 B) 400 C) 1000 D) 1200
Last Answer : 1000
Description : In QAM,both ________ of acarrier frequencyare varied. A) frequencyand amplitude B) phase andfrequency C) amplitudeand phase D) none of the above
Last Answer : amplitudeand phase
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 : In a fiber-optic cable, the signal is propagatedalong theinner core by _______. A) reflection B) refraction C) modulation D) none of the above
Last Answer : reflection
Description : _______ is designed to be usedin wirelessapplications in which stations must be ableto sharethe medium without interception by an eavesdropperand without beingsubject tojamming from a malicious intruder. A) Spread spectrum B) Multiplexing C) Modulation D) None of the above
Last Answer : Spread spectrum
Description : The sharing of a medium and its link by two or more devices is called _______. A) modulation B) encoding C) line discipline D) multiplexing
Last Answer : multiplexing
Description : In ________ TDM, slots are dynamically allocated to improvebandwidth efficiency. A) synchronous B) statistical C) isochronous D) none of the above
Last Answer : statistical