# Analog Communications Questions and Answers – Applications of VSB

This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Applications of VSB”.

1. Frequency Modulated system needs less bandwidth.
a) True
b) False

Explanation: In frequency modulation, frequency of the carrier wave is varied with the instantaneous amplitude of the message signal. Thus, it requires large bandwidth.

2. When bandwidth is the major consideration a narrow and wide band FM can be approximated to?
a) DSB-SC
b) SSB
c) VSB
d) AM

Explanation: For narrow and wide bands frequency modulation, modulation index is respectively smaller and greater than 1. When bandwidth is considered it can be approximated to AM.

3. Which modulation is used in microwave band?
a) Amplitude Modulation
b) Pulse Modulation
c) Frequency Modulation
d) Phase Modulation

Explanation: In pulse modulation, message signal in the form of pulses are varied with respect to width, amplitude or position. It is mostly used for radio navigation, microwave band and for many others.

4. All the output pulses are at full transmitter power for a strong signal in all of the following except ________
a) PAM
b) PFM
c) PCM
d) PWM

Explanation: In pulse modulation, message signal in the form of pulses are varied with respect to width, amplitude or position. Pulse amplitude modulation varies amplitude of pulses for transmission of data. Its’ output pulses are not at full transmitter power for a strong signal and thus it is an exception.

5. In pulse transmitter, the ratio of time on to time off is called ________
a) base
b) bandwidth
c) duty cycle
d) efficiency

Explanation: Duty cycle is the fraction of time in which the system is active. It can also be defined as the ratio of time on to time off of a system. At times, duty cycle, expressed as a percentage, is the ratio of time on to sum of time on and time off.

6. In which of the following modulated systems, quantization noise occurs?
a) TDM
b) FM
c) PWD
d) PCM

Explanation: The difference between an input value and its quantized value is called quantization error or we can also see it as that when an analog number is not converted into an exact digital number. It takes place in pulse code modulation (PCM). Pulse Code Modulation is a technique in which the amplitude of an analogue signal is converted to a binary value represented as a series of pulses.

7. Signal to quantization noise ratio in PCM system depends on _________
a) sampling rate
b) signal bandwidth
c) number of quantization levels
d) nature of carrier wave

Explanation: Pulse code modulation (PCM) is a digital form of communication. For demodulation of PCM, it is necessary to convert it into PAM. Quantization noise occurs in PCM only. Signal to quantization noise ratio depends on the number of quantization levels.

8. Pulse Modulation can be used in automatic landing equipments.
a) True
b) False

Explanation: In pulse modulation, message signal in the form of pulses are varied with respect to width, amplitude or position. It is mostly used for radio navigation, microwave band and for many others.

9. Which of the following modulation is used in data communication?
a) Pulse Modulation
b) Amplitude Modulation
c) Phase Modulation
d) Frequency Modulation

Explanation: In pulse modulation, message signal in the form of pulses are varied with respect to width, amplitude or position. It is mostly used for radio navigation, microwave band and for many others. It is also highly used in data communication.

Sanfoundry Global Education & Learning Series – Analog Communications.

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