1. Which modulation technique utilizes both upper and lower sidebands along with a carrier signal?
a) Amplitude Modulation (AM)
b) Frequency Modulation (FM)
c) Phase Modulation (PM)
d) Pulse Code Modulation (PCM)
Answer: a) Amplitude Modulation (AM)
Explanation: Amplitude Modulation (AM) involves varying the strength (amplitude) of a carrier signal in proportion to the waveform being sent. This modulation technique produces both upper and lower sidebands around the carrier frequency.
2. What does DSB-C stand for in the context of modulation?
a) Double Side Band with Carrier
b) Double Side Band without Carrier
c) Digital Signal Broadcasting with Carrier
d) Direct Single Band Carrier
Answer: a) Double Side Band with Carrier
Explanation: DSB-C refers to Double Side Band with Carrier modulation, where both sidebands are transmitted along with the carrier signal.
3. Which modulation technique only transmits the sidebands without the carrier signal?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: b) DSB-SC
Explanation: DSB-SC (Double Side Band Suppressed Carrier) modulation only transmits the sidebands while suppressing the carrier signal.
4. Which modulation technique offers improved bandwidth efficiency by transmitting only one sideband along with the carrier?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: c) SSB-SC
Explanation: Single Side Band Suppressed Carrier (SSB-SC) modulation transmits only one sideband along with the carrier, thereby offering improved bandwidth efficiency compared to DSB-SC.
5. What is the main advantage of SSB-SC modulation over DSB-SC modulation?
a) Reduced bandwidth requirement
b) Higher signal-to-noise ratio
c) Simplified demodulation process
d) Increased transmission range
Answer: a) Reduced bandwidth requirement
Explanation: SSB-SC modulation requires less bandwidth compared to DSB-SC modulation because it transmits only one sideband along with the carrier.
6. Which modulation technique is commonly used in television broadcasting to conserve bandwidth?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: d) VSB-SC
Explanation: Vestigial Side Band Suppressed Carrier (VSB-SC) modulation is commonly used in television broadcasting to conserve bandwidth while maintaining signal integrity.
7. What is the purpose of generating Vestigial Side Band (VSB) in communication systems?
a) To reduce signal distortion
b) To increase transmission speed
c) To conserve bandwidth
d) To enhance encryption
Answer: c) To conserve bandwidth
Explanation: Vestigial Side Band (VSB) modulation is used to conserve bandwidth in communication systems by transmitting only a portion of one sideband along with the carrier.
8. Which modulation technique involves transmitting both sidebands but only a portion of the carrier signal?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: d) VSB-SC
Explanation: Vestigial Side Band Suppressed Carrier (VSB-SC) modulation involves transmitting both sidebands along with a portion of the carrier signal, which is why it is termed “vestigial.”
9. In which modulation technique is the carrier signal completely eliminated during transmission?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: b) DSB-SC
Explanation: Double Side Band Suppressed Carrier (DSB-SC) modulation completely eliminates the carrier signal during transmission.
10. Which modulation technique is preferred for long-distance radio communication due to its efficient use of power?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: c) SSB-SC
Explanation: Single Side Band Suppressed Carrier (SSB-SC) modulation is preferred for long-distance radio communication due to its efficient use of power and bandwidth.
11. What is the primary disadvantage of DSB-SC modulation?
a) High bandwidth requirement
b) Poor signal-to-noise ratio
c) Complex demodulation process
d) Reduced transmission range
Answer: a) High bandwidth requirement
Explanation: DSB-SC modulation requires a high bandwidth due to the transmission of both sidebands without the carrier signal.
12. Which modulation technique is most susceptible to frequency selective fading in wireless communication?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: a) DSB-C
Explanation: Double Side Band with Carrier (DSB-C) modulation is more susceptible to frequency selective fading because it relies on the transmission of both sidebands along with the carrier signal.
13. Which modulation technique offers improved efficiency in terms of power consumption compared to DSB-SC?
a) DSB-C
b) SSB-SC
c) VSB-SC
d) PCM
Answer: b) SSB-SC
Explanation: Single Side Band Suppressed Carrier (SSB-SC) modulation offers improved efficiency in terms of power consumption compared to DSB-SC modulation.
14. Which modulation technique is commonly used in voice transmission over long-distance radio communication?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: c) SSB-SC
Explanation: Single Side Band Suppressed Carrier (SSB-SC) modulation is commonly used in voice transmission over long-distance radio communication due to its efficiency in power and bandwidth usage.
15. Which modulation technique requires complex demodulation processes at the receiver?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: a) DSB-C
Explanation: Double Side Band with Carrier (DSB-C) modulation requires complex demodulation processes at the receiver to extract the original signal.
16. In SSB-SC modulation, what happens to the lower sideband during transmission?
a) It is transmitted along with the carrier.
b) It is transmitted with reduced power.
c) It is completely suppressed.
d) It is inverted before transmission.
Answer: c) It is completely suppressed.
Explanation: In Single Side Band Suppressed Carrier (SSB-SC) modulation, one sideband (either upper or lower) is completely suppressed during transmission to conserve bandwidth.
17. What is the primary purpose of modulation in communication systems?
a) To increase the power of the signal
b) To reduce the bandwidth requirement
c) To improve the clarity of the signal
d) To simplify the demodulation process
Answer: b) To reduce the bandwidth requirement
Explanation: The primary purpose of modulation in communication systems is to reduce the bandwidth requirement while preserving the integrity of the transmitted signal.
18. Which modulation technique is commonly used in AM radio broadcasting?
a) DSB-C
b) DSB-SC
c) SSB-SC
d) VSB-SC
Answer: a) DSB-C
Explanation: Double Side Band with Carrier (DSB-C) modulation is commonly used in AM (Amplitude Modulation) radio broadcasting.
19. What is the main advantage of VSB-SC modulation in television broadcasting?
a) Improved signal quality
b) Reduced interference
c) Higher transmission speed
d) Increased coverage area
Answer: b) Reduced interference
Explanation: Vestigial Side Band Suppressed Carrier (VSB-SC) modulation reduces interference in television broadcasting, resulting in improved signal quality.
20. Which modulation technique is used in digital communication systems to convert analog signals into digital format?
a) DSB-C
b) PCM
c) SSB-SC
d) VSB-SC
Answer: b) PCM
Explanation: Pulse Code Modulation (PCM) is used in digital communication systems to convert analog signals into digital format for transmission and processing.