1. AM signal have all information in ______ of the carrier.
a) Amplitude
b) Magnitude
c) Frequency
d) Power
Explanation: AM signals have all information in the amplitude of the carrier. Because, AM signal superimpose the exact relative amplitudes of the modulating signal onto the carrier
2. In frequency modulation, the amplitude of modulated carrier signal is ______and its frequency is ______ by the modulating message signal.
a) Constant, constant
b) Varied, constant
c) Constant, varied
d) Varied, varied
Explanation: In frequency modulation (FM), the amplitude of modulated carrier signal is kept constant while its frequency is varied by the modulating message signal. FM is the most popular analog modulation technique used in mobile communication.
3. FM signals have all their information in ______ of the carrier.
a) Amplitude
b) Magnitude
c) Frequency
d) Power
Explanation: FM signal have all their information in the phase or frequency of the carrier. This provides a nonlinear and very rapid improvement in reception quality once a certain minimum received signal level, called FM threshold is achieved.
4. Amplitude modulation has ______ relationship between the quality of the received signal and the power of the received signal.
a) No
b) Non linear
c) Constant
d) Linear
Explanation: In amplitude modulation schemes, there is a linear relationship between the quality of the received signal and the power of the received signal. AM signals superimpose the exact relative amplitudes of the modulating signal onto the carrier
5. FM has _______ noise immunity when compared to amplitude modulation.
a) Same
b) Less
c) No
d) Better
Explanation: FM offers many advantages over amplitude modulation which makes it a better choice for many mobile radio applications. Frequency modulation has better noise immunity when compared to amplitude modulation
6. FM signals are _____ susceptible to atmospheric and impulse noise as compared to AM.
a) Largely
b) Less
c) Not
d) Better
Explanation: FM signals are represented as frequency variations rather than amplitude variations. Therefore, FM signals are less susceptible to atmospheric and impulse noise.
7. Which of the following is an advantage of AM systems in comparison to FM sysytems?
a) Occupy less bandwidth
b) Superior performance in fading
c) Better noise immunity
d) Not susceptible to impulse noise
Explanation: AM signals are able to occupy less bandwidth as compared to FM signals, since the transmission system is linear. Small scale fading causes rapid fluctuations in the received signal. Thus, FM offers superior qualitative performance in fading when compared to AM.
8. An FM signal is a ______ envelope signal.
a) Varied
b) Small
c) Large
d) Constant
Explanation: An FM signal is a constant envelope signal. It is due to the fact that the envelope of the carrier does not change with changes in the modulating signal. Hence, the transmitted power of an FM signal is constant regardless of the amplitude of the message signal.
9. Which of the following is a drawback of FM systems?
a) Burst noise
b) Susceptible to atmospheric noise
c) Wider frequency band
d) Poor performance in fading
Explanation: FM systems have many advantages over AM systems. They also have certain disadvantages. FM systems require a wider frequency band in transmitting media in order to obtain the advantages of reduced noise and capture effect. It is generally several times as large as that needed for AM.
10. Carrier signal in modulation technique is _______ signal.
a) High frequency
b) Low frequency
c) High amplitude
d) Low amplitude
Explanation: Carrier signal in modulation technique is a high frequency signal. In amplitude modulation, the amplitude of a high frequency carrier signal is varied in accordance to the instantaneous amplitude of the modulating signal