Demodulation Question & Answers January 24, 2022 By WatElectronics This article lists 100 Demodulation MCQs for engineering students. All the Demodulation Questions & 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 Demodulation. In the digital world, digital communication is possible between 2 main components transmitter, receiver, and channel. For secure communication to occur the messages sent from transmitter to receiver must be encrypted and maintained well from data being tampered with due to external factors such as the addition of noise. This can be achieved by 2 techniques in digital communication namely modulation and demodulation. Modulation is the process of representing data in radio wave format done at the sender's end and Demodulation is the process of converting radio wave format to data format done at the receiver's end. Radio receivers were the first application where the concept of demodulation came in to picture. Where the data from sender to receiver end was communicated in digital pulse form using Morse code. During this process when the receiver detected there is a radio signal it produces a click sound notifying the user that message has arrived. A demodulated wave comprises a carrier wave, message, and data. Demodulators are classified into 2 types namely rectification and mixing. A synchronous type demodulator is classified into two types namely open loop and closed loop. Multiple demodulation techniques are performed using carrier recovery, frame synchronization, and pulse compression. Demodulators are used in modems, optical cables, and telephones. 1). The process of separating original message from encrypted message is _____ process? Modulation Demodulation Decryption Both b and c Hint 2). How many communication components do digital communication system comprises of? 2 3 4 5 Hint 3). The process of representing data in radio wave form is called ____? Modulation Demodulation Decryption All the above Hint 4). A demodulated wave comprises of ____ wave? Carrier wave Message Data All the above Hint 5). At which of the following end demodulation takes place? Receiver Transmitter Channel All the above Hint 6). At which of the following end modulation takes place? Receiver Transmitter Channel All the above Hint 7). Which of the following is the intermediate component in digital communication? Receiver Transmitter Channel All the above Hint 8). A demodulator is a ____ circuit? Mechanical Electrical Electronic Chemical Hint Read more about the Computer Ports. 9). In software terminology a demodulator is _____? Computer program Software Hardware design Both a and b Hint 10). A device that performs a process to represent the original senders message is called ____? Modulator Demodulator Amplifier All the above Hint 11). A device that performs modulation is called ____? Modulator Demodulator Amplifier All the above Hint 12). The output obtained from demodulator are in the form of_____? Analog audio signal Analog video signal Binary data All the above Hint Read more about Analog Modulation. 13). A binary data is represented in the form of ____? 0’s 1’s ABC Both a and b Hint 14). An analog signal is represented in the form of ____? Audio Video Sound All the above Hint 15). ____ is used to extract data from carrier wave? Modulator Demodulator Amplifier All the above Hint 16). A demodulator extracts data in ____ fashion from carrier wave? Serial Parallel Concurrently All the above Hint 17). A high frequency EM wave is called ____? Carrier signal Carrier Message Both a and b Hint 18). A carrier wave has ___ quantity of frequency? High Low Zero Infinity Hint Read more about Radio Frequency. 19). A carrier wave is transmitted using ____ type of waves? Light Radio Visible All the above Hint 20). Audio signal is represented in form of ____? Heat Light Sound All the above Hint 21). Which of the following is the frequency of audio signal? 20 to 20000Hz 200 to 20000Hz 20 to 20000Hz 30 to 3000Hz Hint 22). Which of the following is the form of video signal? Broadcasting Visual media display Recording All the above Hint 23). Which of the following are the demodulators? Modems Radio receivers Receivers All the above Hint 24). Using which of the following medium carrier signal is received at demodulator? Optical fiber Coaxial cable Telephone line All the above Hint Read more about Optical Fiber. 25). A coaxial cable is also called ____? Coax Electric cable Bi cable Both a and b Hint Demodulation Interview Questions and Answers 26). A demodulation process occurs based on _____? Amplitude Frequency Phases All the above Hint 27). A demodulator is also called ______? Detector Definer Defender All the above Hint 28). Which of the following techniques are performed using demodulator? Carrier recovery Frame Synchronization Pulse compression All the above Hint 29). The waves in demodulator are transferred ______? Linearly Non linearly Constant All the above Hint 30). AM stands for ____? Amplitude modulation Angle modulator Agile Modulation All the above Hint Read more about Amplitude Modulation. 31). FM stands for _____? Frequency modulation Frequent modulation Fan-in modulation All the above Hint 32). Which of the following is used for FM demodulation? Frequency detector Phase detector Angular detector Both a and b Hint 33). A carrier recovery circuit estimates ______? Phase Frequency Amplitude Both a and b Hint 34). In transmitter a carrier based system modulates carrier wave with _____signal? Baseband Sideband Wideband All the above Hint 35). A baseband signal has _____ to higher frequencies? Unmodulated Demodulated Modulated All the above Hint 36). Which of the following are the methods of carrier recovery? Non data aided Multiply filter divide Costas loop All the above Hint 37). In bit slip type demodulation technique bits are ____ caused due to clock drift variations? Bit loss Bit gain Bit division Both a and b Hint 38). Which of the following are the reasons behind bit slip type demodulation technique? Clock drift based variation Buffer overflow Synchronous protocol All the above Hint 39). Which of the following is the reason for buffer overflow In bit slip type demodulation technique? Exceed in transmitters clocks rate than receivers Drop of multiple bits Termination in modulation Both a and b Hint 40). Which of the following overcomes timing between receiver and transmitter are? Synchronous clocks Asynchronous clocks Timers All the above Hint 41). Which of the following demodulation technique defines the process of receiving data that is framed? Framing Bit slip Clock recovery All the above Hint 42). A framing process is also called? Frame synchronization Breaking Division All the above Hint 43). A framing process frames _____? Distinct bits Sync words Similar words Both a and b Hint 44). At which of the following condition receiver in framing process performs resynchronization? Temporary interruption of transmission Occurrence of bit slip Retransmission Both a and b Hint 45). Frame synchronization schemes are classified in to ____ types? 2 3 4 5 Hint 46). A rake receiver is also called ___? RF receiver Radio receiver Radio detector Both a and b Hint 47). A multiple sub receiver is also called_____? Fingers Rangers Receiver Transmitters Hint 48). A received signal strength indicator is measurement of _____ in received radio signal? Amplitude Frequency Power Waves Hint 49). A detector that takes higher value of AM signals frequency and provides resultant wave is called ___? Envelope detector Envelope demodulator Envelope amplifier Both a and b Hint 50). An envelope detector is also called ____? Peak detector Envelope demodulator Original detector Both a and b Hint Demodulation Important Questions for Interviews 51). An envelope detector demodulates ____ signal? Original signal Carrier wave Message All the above Hint 52). Demodulators are classified in to ____ types? 1 2 3 4 Hint 53). A rectification type demodulators is also called ____? Synchronous demodulator Asynchronous demodulator Non synchronous demodulator Both b and c Hint 54). Which of the following are the examples of non synchronous demodulator? RMS to DC convertors Kalman filter Lyapunov filter All the above Hint 55). A mixing type demodulators is also called ____? Synchronous demodulator Asynchronous demodulator Non synchronous demodulator Both b and c Hint 56). Which of the following are the examples of synchronous demodulator? RMS to DC convertors Kalman filter Lyapunov filter Both b and c Hint 57). A synchronous type demodulator are classified in to _____ types? 2 3 4 5 Hint 58). Which of the following is an open loop synchronous type demodulator? Kalman filter Lock in amplifier Coherent demodulator Both b and c Hint Read more about Amplifiers. 59). A high band lock in amplifier is a ____ type of demodulator? Synchronous Asynchronous Rectification Both a and b Hint 60). Which of the following is not closed loop demodulator? Lyapuno filter Lock in amplifier Kalman filter Both a and b Hint 61). A FM type demodulation is classified in to ____ types? 1 2 3 4 Hint 62). Which of the following are the examples of direct type FM demodulator? PLL Slope detector Balanced slope detector Both b and c Hint 63). Which of the following are the examples of indirect type FM demodulator? PLL Slope detector Balanced slope detector Both b and c Hint 64). Which of the following is the primary function of demodulator? Recovering original signal Removing noise Adding bits All the above Hint 65). A device that converts frequency of variation in a modulated signal to amplitude variation using discriminator is called____? AM FM PM All the above Hint 66). Which of the following is the input applied to FM demodulator_______? Frequency Variation Amplitude Variation Pulse variation All the above Hint 67). Which of the following is the output applied to FM demodulator_______? Frequency Variation Amplitude Variation Pulse variation All the above Hint 68). An FM demodulator should be _____ to amplitude changes? Sensitive Insensitive Disturbed Both a and c Hint 69). In FM demodulator carrier frequency fall on _____ side of resonant frequency? Uni Dual Multi Zero Hint 70). Entire frequency in FM demodulator should fall on______ region of transfer curve of tuned circuit? Linear Non linear Active Both b and c Hint 71). The output obtained from slope type detector is given as input to ____ Transistor Resistor Capacitor Diode Hint 72). ______ value should be constant while providing feedback to load in an slope detector. Resistance Capacitance Time Inductance Hint 73). Which of the following are the limitations of slope detector? Inefficient Reacts to all amplitudes Difficulty in tuning All the above Hint 74). A slope detector has _______frequency range? Limited High Constant Zero Hint 75). A balanced type slope detector uses ______ numbers of slope detectors? 1 2 3 4 Hint Demodulation Quiz Questions and Answers. 76). Balanced type slope detector is connected to opposite ends of _____? Load Center tapped transformer Open circuited All the above Hint 77). The phase of balanced slope detector is ______? 90 degrees 180 degrees out of phase 120 degrees 45 degrees Hint 78). The output from balanced slope detector is taken from _____ combination of loads? Series Parallel Concurrent Both b and c Hint 79). Which of the following are the disadvantages of balanced slope detector? Multiple frequencies Limited in amplitude Non linearity All the above Hint 80). In which of the following discriminator same frequency tuned in all circuits? Foster-seley phase discriminator Slope detector Fostoer seley phase discriminator All the above Hint 81). Which of the following is the advantage of foster delay phase detector? Linearity Same frequency Non linearity Both a and b Hint 82). Which of the following is the disadvantage of foster delay phase detector? Linearity Same frequency Non linearity Limitation in amplitude Hint 83). Which of the following is the advantage of radio detector? Possibility of amplitude limiting Linearity Noise free Both a and b Hint 84). Which of the following are the disadvantages of radio detector? Advanced demodulators are cascaded for better operation Noisy Inefficient All the above Hint 85). PLL stands for_____? Phase Lock Loop Phase Lead Loop Pin Lock Loop Pin Loop Lock Hint 86). A PLL is a ____ device? Electric Mechanic Electronic Software Hint Read more about Electronic Circuits. 87). A PLL comprises of ____ as basic component? Oscillator Amplifier Rectifier All the above Hint 88). ____ are the types of oscillators used in PLL? Voltage driven Current driven Resistance Both a and b Hint 89). Which of the following is the function of phase discriminator? Comparing 2 signals Generating voltage Providing resistance Both a and b Hint 90). VCO stands for ____? Voltage Controlled Oscillator Violet Controlled Oscillator None of the above Hint 91). A VOC generates _____ types of signals? RF UV Light All the above Hint 92). Which of the following is the input to PLL? FM signal AM signal PM signal Both a and c Hint 93). How many components are used in PLL? 1 2 3 4 Hint 94). In PLL a control voltage is ______ to input frequency change? Directly proportional Indirectly proportional Inversely proportional Both b and c Hint 95). A PLL maintains ______ parameter low for following modulated signal? Time constant Slew rate Load All the above Hint 96). The value of free running frequency in PLL is made equal to _____ in FM wave? Carrier frequency Message Original data All the above Hint 97). The value of lock range in PLL is ____ the maximum deviation of signal? 1 time 2 times less 0 Hint 98). Linearity in PLL is governed by ______characteristics of VCO? Voltage to frequency Voltage to frequency Current to frequency All the above Hint 99). The quantity of distortion in PLL is ____? High Zero Low Constant Hint 100). Frequency is measured in terms of _____? Ohms Farads Watts Hertz Hint Time is Up! Time's up
