This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Source of Information”.
1. FM stands for ________
a) Frequency Modulation
b) Frequency Moderator
c) Frequent Moderator
d) Frequency Demodulation
Explanation: FM stands for Frequency Modulation. It is the encoding of information on a carrier wave by varying the instantaneous frequency of the wave.
2. Why a sinusoidal signal is considered analog?
a) It moves in both positive and negative direction
b) It is positive for one half cycle
c) It is negative for one half cycle
d) It has infinite amount of steps between a maximum and minimum value
Explanation: A sinusoidal wave is an analog signal. An analog electrical signal is a signal with an infinite amount of ‘steps’ between a minimum and maximum value. Say a signal has 0V as the minimum and 4.2V as the maximum voltage, that means the signal could be 3.3V or 3.345464634546….V.
3. The minimum height of antenna required for transmission in terms of ʎ is ________
Explanation: For effective transmission length of antenna should be one forth of ʎ. (L = ʎ⁄4 where ʎ = c⁄f). Actually the reason for maintaining antenna height to ʎ⁄4 is for matching impedance.
4. What do you understand by the term analog communication?
a) A continuous signal with varying phase or amplitude
b) A discrete signal
c) A numerical coded signal
d) A suitable method for long distance communication
Explanation: Analog communication means that information is transmitted in the form of a continuous signal. Coding is applied in case of digital communication. Moreover for a long distance communication, it suffers from many losses such as distortion and interference.
5. What is Demodulation?
a) Process of varying one or more properties of a periodic waveform
b) Recovering information from modulated signal
c) Process of mixing a signal with a sinusoid to produce a new signal
d) Involvement of noise
Explanation: Demodulation is the process of recovering information from a modulated carrier wave while it is modulation in which properties of a periodic waveform is varied. A modulator is a device that performs modulation while demodulator performs demodulation. A modem can perform both functions.
6. Data transmitted for a given amount of time is called ________
Explanation: Bandwidth is defined as a range within a band of frequencies or wavelengths. It is also defined as the amount of data that can be transmitted in a fixed amount of time.
7. If Output can be represented as linear combination of input then ________
a) The system is linear
b) The system is causal
c) The system is non causal
d) The system is time invariant
Explanation: The input signal is broken into many components, each component is processed individually, and the result is finally reunited . It also follows superposition property.
8. Amplitude Modulation suffers from ________
b) Intra Modulation
c) Cross Modulation
d) Frequency Modulation
Explanation: Cross modulation is generally occurred in receivers receiving an AM signal in the presence of other strong AM signal. Actually the modulation from the strong signal was cross modulated and appeared on the weaker signal being received.
9. Medium which sends information from source to receiver is called ________
Explanation: Channel is a medium through which a message is transmitted. Transmitter is used process the electrical signal from different aspects. Transducer is used to convert one form of energy into another form. Now when the signal is received at the output of the channel, it consists noise. So the role of receiver is to estimate the original message signal.
10. Telephones send information through wires in form of ________
a) radio signals
b) electrical signal
c) electromagnetic waves
Explanation: A telephone converts sound into electronic signals which is suitable for transmission over long distances, where it is converted to sound again. The essential components of telephone are a microphone which acts as a transmitter and an earphone which acts as a receiver.
11. Cell phones sent information in form of ________
b) electrical signals
c) radio signals
d) electromagnetic waves
Explanation: Cell phones send electromagnetic waves from one base station to other. The waves are sent through antennas. This is called wireless communication.
12. Ability of receivers to select the wanted signals among various incoming signal is called ________
Explanation: Ability of receiver to select wanted signal from various incoming signal is called selectivity. It rejects the other signals at closely lying frequencies. Sensitivity is the minimum magnitude of input signal required to produced a specified output. While modulation is the process of varying one or more properties of carrier signal.
13. Which device is used for tuning the receiver according to incoming signal (especially in TV)?
a) Low pass filter
b) High pass filter
c) Zener diode
d) Varacter diode
Explanation: Varacter diode is a tuning diode having variable capacitance. Tuning or Varacter diodes are operated in reverse bias and therefore no current flows through it. Varacter diodes are mainly used in Voltage Controlled Oscillators (VCOs) and RF Filters.
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.