Analog Communications Questions and Answers Part-1

1. What do you understand by the term analog communication?
a) A method in which one of the properties of a carrier signal varies in proportion to an instantaneous value of modulation signal
b) A numerical coded communication
c) A suitable method for long distance communication
d) A way for data and computer communication

Answer: a
Explanation: Analog communication means that information is transmitted in the form of a continuous signal through the process of modulation. Rests of the options are applicable for digital communication, where coding is applied.

2. Data transmitted for a given amount of time is called ________
a) Frequency
b) Power
c) Noise
d) Bandwidth

Answer: d
Explanation: Data transmitted for a given amount of time is called Bandwidth

3. Telephones send information through wires in form of ________
a) microwaves
b) electrical signal
c) electromagnetic waves
d) radio signals

Answer: b
Explanation: A telephone converts sound waves into electrical signals which are suitable for transmission over long distances, where it is converted to sound waves again, through a transducer. The essential components of a telephone are a microphone which acts as a transmitter and an earphone which acts as a receiver.

4. What is Demodulation?
a) Recovering information from a modulated signal
b) Process of mixing a signal with a sinusoid to produce a new signal
c) Involvement of noise
d) Process of varying one or more properties of a periodic waveform

Answer: a
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 the demodulator performs demodulation. A modem can perform both functions.

5. Cell phones sent information in form of ________
a) electrical signals
b) infrared Waves
c) microwaves
d) radio waves

Answer: d
Explanation: Cell phones transmit information in form of radio waves to communicate with each other. Radio waves are transmitted in all directions by the cell phone, and they travel at the speed of light in air or vacuum.

6. FM stands for ________
a) Frequency Modulation
b) Frequency Mixer
c) Frequent Multiplier
d) Frequency Modulator

Answer: a
Explanation: FM stands for Frequency Modulation. It is the encoding of information on a carrier wave by varying its frequency with respect to the instantaneous amplitude of the message signal. Rest other options are the components used in the process of frequency modulation.

7. Which device is used for tuning the receiver according to incoming signal (especially in TV)?
a) Low pass filter
b) Zener diode
c) Varacter diode
d) High pass filter

Answer: c
Explanation: Varactor diode is a diode working in the reverse-bias because of which no current flows through it. It has variable capacitance which varies with applied voltage. Varactor diodes are mainly used in Voltage Controlled Oscillators (VCOs) and RF Filters for tuning the receiver to the incoming signal or different stations.

8. Medium which sends information from source to receiver is called ________
a) Loudspeaker
b) Channel
c) Transmitter
d) Transducer

Answer: b
Explanation: Channel is the medium through which information is transmitted. Transmitter is used to process the electrical signal through different aspects. The transducer is used to convert a message signal to an electrical signal. Loudspeaker is a type of Transducer.

9. Why a sinusoidal signal is considered analog?
a) It is positive for one half cycle
b) It is negative for one half cycle
c) It moves in both positive and negative direction
d) It has an infinite number of amplitudes in the range of values of the independent variable

Answer: d
Explanation: A sinusoidal wave is an analog signal. An analog electrical signal is a signal with infinite number of amplitudes in the range of values of independent variable. Analog signals can take on any value in the continuous interval.

10. Amplitude Modulation suffers from ________
a) IntraPulse Modulation
b) Carrier Suppression
c) Cross Modulation
d) Side-band Suppression

Answer: c
Explanation: Cross modulation generally occurs in receivers receiving an AM signal in the presence of other strong AM signal. The modulation from the strong signal cross modulates and appears on the weaker signal being received.