Digital Modulation Question & Answers February 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 None Hint 2). How many main components are used in digital communication? 1 2 3 4 None Hint 3). Modulation of a signal is performed at ____ component in digital communication? Transmitter Receiver Channel Both b and c None Hint 4). De-modulation of a signal is performed at ____ component in digital communication? Transmitter Receiver Channel Both b and c None Hint 5). Digitally modulated signals are represented using _____? Pulses Symbols Finite states All the above None Hint 6). Each symbol holds ____ number of information? 1 2 3 N None Hint 7). Which of the following are the advantages of digital modulation? Finite process Higher noise immunity Multiplexing property All the above None Hint 8). Which of the following are the types of analog modulation? AM PM FM All the above None Hint 9). Data in digital modulation is ______ form? Continuous Discrete Discontinuous Both b and c None Hint 10). Which of the following are the digital modulation techniques? ASK PSK FSK All the above None Hint 11). Abbreviate ASK? Amplitude Shift Keying Amplitude Side Keying Angle Shift Keying Angle Side Keying None Hint Read more about ASK. 12). Abbreviate PSK? Phase Shift Keying Phase Side Keying Push Shift Keying Push Side Keying None Hint Read more about PSK. 13). Abbreviate FSK? Frequency Shift Key Frequency Side Key Fast Shift Key Fast Side Key None Hint 14). Which of the following are the applications of ASK? Fiber optics IR remote device Trans receivers All the above None Hint 15). ASK modulation is also called ____? OOK On/Off Off Both a and b None Hint Digital Modulation Questions and Answers 16). Which of the following is the application of FSK? Modems Telemetry systems Radiosondes All the above None Hint 18). FSK transmitters deploys ____ number of oscillators? 1 2 3 4 None Hint 17). FSK is further classified into ____ types? 2 3 4 5 None Hint 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 None Hint 20). How many inputs are provided to FSK block of 2 by 1 MUX? 2 3 4 1 None Hint Read more about MUX. 21). FSK modulated signals are of ____ types? 2 3 4 5 None Hint 22). A mark frequency is represented with ______ logic? 1 0 X None of the above None Hint 23). A space frequency is represented with ______ logic? 1 0 X None of the above None Hint 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 None Hint 25). The process of reconstructing back the original signal is called ____? Modulation Demodulation Phasing None of the above None Hint 26). How many types of FSK demodulations exists? 1 2 3 4 None Hint 27). Analog signals exhibits ____ that degrades signals strength? Noise Distortion Interference All the above None Hint 28). How many input signals are required in ASK? 1 2 3 4 None Hint 29). A coherent detection is also called ___? Synchronous demodulation Asynchronous demodulation Zero demodulation Both a and c None Hint 30). A non-coherent detection is also called ___? Synchronous demodulation Asynchronous demodulation Zero demodulation Both a and c None Hint Digital Modulation MCQs for Quiz 31). Which of the following are the components of ASK coherent detection block? LPF Multiplier Sample and Hold Circuit All the above None Hint 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 None Hint Read more about Comparator. 33). Which of the following are the applications of PSK? Local oscillator Optical communications Multi channel WDM All the above None Hint 34). Which of the following are the advantages of PSK? Higher efficiency Enhance security Higher data rate All the above None Hint 35). Which of the following are the disadvantages of PSK? Low BW efficiency Non-coherent based signal High sensitive All the above None Hint 36). PSK are classified in to ____ types? 3 4 5 6 None Hint Read more about PSK. 37). QPSK stands for ____? Quadrature PSK Quantum PSK Quilt PSK All the above None Hint 38). M- ary digital technique transmits ____ number of bits per time? 1 2 0 >2 None Hint 39). M-ary techniques are classified in to ___ types? 2 3 4 5 None Hint 40). Which of the following are the modulation methods of AM? PAM QAM PSK Both a and b None Hint Digital Modulation MCQs for Interviews 41). Which of the following are the modulation methods of continuous phase modulation? GMSK MSK CPFSK All the above None Hint 42). Which of the following are the modulation methods of Trellis coded modulation? PSK QAM MSK Both a and b None Hint 43). Binary data is represented in form of _____? 0’s 1’s X Both a and b None Hint 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 None Hint 45). A modem is a combination of ____? Modulator Demodulator Detector All the above None Hint 46). ____ is the occupied frequency band by modulated signal? Base band Pass band Zero band All the above None Hint 47). ____ term defines logic state? Bit Symbol Data All the above None Hint 48). Symbol rate is also called _____? Bit rate Baud rate Sign rate All the above None Hint 49). Which of the following is the formula of baud rate? 2^N 2N 2/N N/2 None Hint 50). A carrier signal is of ___ wave shape? Sine Rectangle Triangle Pulse None Hint Please fill in the comment box below. Time's up
