Digital Modulation Question & AnswersFebruary 28, 2022 By WatElectronics This article lists 50 Digital Modulation MCQs for engineering students. All the Digital Modulation Questions and Answers given below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up their fundamentals on Digital Modulation.Digital communication deals with transmitting and receiving the data in digital form. Three main blocks involve in digital communication namely, transmitter, receiver, and communication channel. Where the transmitter is present at the sender's end and the receiver at the recipient's end and in between lies the communication channel. Modulation is the procedure to represent a radio wave by converting the raw data added with an electronic/optical-based carrier signal into digital /radio waveform. Modulation is classified into 2 types Analog modulation and Digital modulation.Analog modulation is further classified as Amplitude Modulation (AM), Phase Modulation (PM), and Frequency Modulation (FM). Digital modulation is the method of encoding binary information (digital data) of a signal in the form of phase, frequency, and amplitude of the transmitted signal. Digital modulations are classified as Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), and Phase Shift Keying (PSK). Where each of the digital modulation for AM(PAM, QAM), PM (PSK, DPSK, OPSK), FM (FSK), continuous phase modulation (GMSK, MSK, CPFSK) and Trellis coded modulation (PSK and QAM) have further modulation methods. Digital modulation benefits in terms of finite process, higher noise immunity, and multiplexing property. Digital modulation is deployed in modems, telemetry systems, radiosondes, etc.1). The source used in digital communication is discrete in terms of _____ parameter? Amplitude Time Frequency Both a and b Hint2 parameters.2). How many main components are used in digital communication? 1 2 3 4 HintOdd value.3). Modulation of a signal is performed at ____ component in digital communication? Transmitter Receiver Channel Both b and c HintSenders end.4). De-modulation of a signal is performed at ____ component in digital communication? Transmitter Receiver Channel Both b and c HintReceipting.5). Digitally modulated signals are represented using _____? Pulses Symbols Finite states All the above Hint3 forms.6). Each symbol holds ____ number of information? 1 2 3 N HintMaximum value.7). Which of the following are the advantages of digital modulation? Finite process Higher noise immunity Multiplexing property All the above Hint3 advantages.8). Which of the following are the types of analog modulation? AM PM FM All the above Hint3 types.9). Data in digital modulation is ______ form? Continuous Discrete Discontinuous Both b and c HintAperiodic.10). Which of the following are the digital modulation techniques? ASK PSK FSK All the above Hint3 types.11). Abbreviate ASK? Amplitude Shift Keying Amplitude Side Keying Angle Shift Keying Angle Side Keying HintSignal heights measurement. Read more about ASK.12). Abbreviate PSK? Phase Shift Keying Phase Side Keying Push Shift Keying Push Side Keying HintRelated to angle of signal. Read more about PSK.13). Abbreviate FSK? Frequency Shift Key Frequency Side Key Fast Shift Key Fast Side Key HintMeasured in Hertz.14). Which of the following are the applications of ASK? Fiber optics IR remote device Trans receivers All the above Hint3 applications.15). ASK modulation is also called ____? OOK On/Off Off Both a and b Hint2 names.Digital Modulation Questions and Answers16). Which of the following is the application of FSK? Modems Telemetry systems Radiosondes All the above Hint3 applications.18). FSK transmitters deploys ____ number of oscillators? 1 2 3 4 HintOdd number.17). FSK is further classified into ____ types? 2 3 4 5 HintEven number.19). Which of the following is the advantage of continuous phase frequency shift keying? Minimizes sideband power Minimizes interference Eliminates discontinuous in phase All the above Hint3 advantages.20). How many inputs are provided to FSK block of 2 by 1 MUX? 2 3 4 1 HintOdd value. Read more about MUX.21). FSK modulated signals are of ____ types? 2 3 4 5 HintEven number.22). A mark frequency is represented with ______ logic? 1 0 X None of the above HintHigh logic.23). A space frequency is represented with ______ logic? 1 0 X None of the above HintLogic low.24). Which of the following are the formulas of carrier signals in FM 2by 1 mux? Ac Cos (2wc+ Θ)t Ac Cos (2wc - Θ)t Ac Cos (2wcΘ)t Both a and b Hint2 formulas.25). The process of reconstructing back the original signal is called ____? Modulation Demodulation Phasing None of the above HintPerformed at receivers end.26). How many types of FSK demodulations exists? 1 2 3 4 HintEven number.27). Analog signals exhibits ____ that degrades signals strength? Noise Distortion Interference All the above Hint3 parameters.28). How many input signals are required in ASK? 1 2 3 4 HintEven number.29). A coherent detection is also called ___? Synchronous demodulation Asynchronous demodulation Zero demodulation Both a and c HintPeriodic detection.30). A non-coherent detection is also called ___? Synchronous demodulation Asynchronous demodulation Zero demodulation Both a and c Hintdiscreate time.Digital Modulation MCQs for Quiz31). Which of the following are the components of ASK coherent detection block? LPF Multiplier Sample and Hold Circuit All the above Hint3 components. Read more about Low Pass Filter.32). Which of the following are the components of ASK non-coherent detection block? LPF Square law detector Comparator All the above Hint3 components. Read more about Comparator.33). Which of the following are the applications of PSK? Local oscillator Optical communications Multi channel WDM All the above Hint3 applications.34). Which of the following are the advantages of PSK? Higher efficiency Enhance security Higher data rate All the above Hint3 advantages.35). Which of the following are the disadvantages of PSK? Low BW efficiency Non-coherent based signal High sensitive All the above Hint3 disadvantages.36). PSK are classified in to ____ types? 3 4 5 6 HintEven number. Read more about PSK.37). QPSK stands for ____? Quadrature PSK Quantum PSK Quilt PSK All the above HintTwo bits are modulated at once.38). M- ary digital technique transmits ____ number of bits per time? 1 2 0 >2 HintHigher value.39). M-ary techniques are classified in to ___ types? 2 3 4 5 HintOdd number.40). Which of the following are the modulation methods of AM? PAM QAM PSK Both a and b Hint2 types.Digital Modulation MCQs for Interviews41). Which of the following are the modulation methods of continuous phase modulation? GMSK MSK CPFSK All the above Hint3 types.42). Which of the following are the modulation methods of Trellis coded modulation? PSK QAM MSK Both a and b Hint2 methods.43). Binary data is represented in form of _____? 0’s 1’s X Both a and b HintEither of 2 digits.44). In which of the following digital modulation carrier wave switches between 0 and 1 based on applied input? ASK PSK FSK All the above HintLow-frequency RF applications.45). A modem is a combination of ____? Modulator Demodulator Detector All the above Hint3 combination.46). ____ is the occupied frequency band by modulated signal? Base band Pass band Zero band All the above HintA range of frequencies occupied by a signal that has not been modulated to higher frequencies.47). ____ term defines logic state? Bit Symbol Data All the above HintBinary value, either 0 or 1.48). Symbol rate is also called _____? Bit rate Baud rate Sign rate All the above HintThe number of bits that are conveyed or processed in a given unit of time.49). Which of the following is the formula of baud rate? 2^N 2N 2/N N/2 HintPower value.50). A carrier signal is of ___ wave shape? Sine Rectangle Triangle Pulse HintA periodic waveform. Please fill in the comment box below. Time is Up! Time's up
