This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Non Linear Device”.
1. Who originated the theory of radio waves?
Explanation: Maxwell is the first person who originated the theory of radio waves. After some years, it was Hertz who applied Maxwell theories to the production and reception of waves.
2. If we compared to the USB, the power in the LSB is ________
b) twice of USB
d) half of USB
Explanation: The two bands i.e. upper sideband and lower sideband generally contains same information. They also has same power.
3. Which effect is characteristic of FM reception in a noisy environment?
a) threshold effect
b) capture effect
c) bessel effect
d) carson’s effect
Explanation: Threshold effect has low output signal to noise ratio. It contains large noise as compared to input signal to envelope detector. In threshold effect, detection of message signal is difficult.
4. Mathematically, the number of sidebands in frequency modulated system is _________
Explanation: If we consider the number of sidebands in frequency modulated system, we found that the number of sidebands is infinite.
5. How an AM radio station increase its signal-to-noise ratio?
a) by increasing its modulation index
b) by decreasing its modulation index
c) by maintaining a constant modulation index
d) by increasing the frequency
Explanation: Signal to noise ratio is the ratio of signal power to the noise power. It is often described in decibels. It is directly proportional with modulation index and thus it increases with modulation index.
6. Which statement is true about an SCA signal?
a) it can use amplitude modulation
b) it can use frequency modulation
c) is monaural
d) it can use amplitude as well as frequency modulation and is also monaural
Explanation: STC stands for Subsidiary Communication Authority. SCA is a separated data channel which is transmitted along with the main signal over a broadcast station. It can either be amplitude modulated or frequency modulated.
7. What is the use of pre-emphasis?
a) to increase the signal to noise ratio for higher audio frequencies
b) to allow stereo audio to be carried by FM stations
c) to increase the signal to noise ratio for all audio frequencies
d) to increase the signal to noise ratio for lower audio frequencies
Explanation: Pre emphasis is used to equalize the modulating signal drive power in terms of deviation ratio. It is also helpful in increasing S/N ratio but for lower audio frequencies only.
8. In FM system, capture effect is observed when an FM receiver switching suddenly between two stations having nearby frequencies.
Explanation: Capture effect is related with FM reception. In capture effect, only the stronger of two signals at, or near, the same frequency will be demodulated.
9. What is the full form of NBFM?
a) Narrow band frequency modulation
b) National broadcast frequency modulation
c) Near band frequency modulation
d) Non broadcast frequency modulation
Explanation: NBFM stands for Narrow band frequency modulation. For NBFM, bandwidth should be less than 1.
10. Why the bandwidth of an FM signal is considered to be limited?
a) because there can only be a finite number of sidebands
b) because it is equal to the frequency deviation
c) because it is band-limited at the receiver
d) because the power in the outer sidebands is negligible
Explanation: In frequency modulated system, frequency of carrier is varied in proportion with the wave which is transmitted. Its bandwidth kept limited because the power of outer sidebands in frequency modulated system is negligible.
Sanfoundry Global Education & Learning Series – Analog Communications.
To practice all areas of Analog Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.