# Analog Communications Questions and Answers – Noise in Pulse Modulated System

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This set of Analog Communications Problems focuses on “Noise in Pulse Modulated System”.

1. Fiber-optic cable can be used to connect a transmitter to an antenna.
a) True
b) False

Explanation: A fiber-optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages. Fiber-optic cable cannot be used to connect a transmitter with an antenna. An antenna is a collection of conductors is connected electrically to the transmitter.

2. Scattering causes _________
a) refraction
b) loss
c) dispersion
d) reflection

Explanation: In scattering, particles are forced to deviate from a straight trajectory due to non-uniformities in the medium. Thus, it causes loss of data.

3. The loss in single-mode fiber optic cable due to the glass is about ________
a) 40 dB per km
b) 0.4 dB per km
c) zero
d) 100 dB per km

Explanation: A duplex arrangement is a cordless telephone that uses separate frequencies for transmission in base and portable units. In duplex communication, sender and receiver can interact simultaneously while in half-duplex, sender and receiver communicates one at a time.

4. The loss in single-mode fiber optic cable due to the splice is about ________
a) 0.2 dB per km
b) 0.02 dB per km
c) 0.0002 dB per km
d) 2 dB per km

Explanation: A fiber-optic cable consist of a bundle of glass threads, each of which is capable of transmitting messages. The loss in single-mode fiber optic cable due to the splice is about 0.02 dB per km. In single mode fiber optical cable, only a single light ray is transmitted.

5. The loss in single-mode fiber optic cable due to the connector is about ________
a) 0.2 dB per km
b) 0.02 dB per km
c) 0.0002 dB per km
d) 2 dB per km

Explanation: A fiber-optic cable consist of a bundle of glass threads, each of which is capable of transmitting messages. The loss in single-mode fiber optic cable due to the connector is about 0.2 dB per km. In single mode fiber optical cable, only a single light ray is transmitted.

6. What is the full form of FITL ________
a) Fiber Input Timing Loss
b) Fibre Impedance To The Loop
c) Fiber Input Timing Loop
d) Fiber In The Loop

Explanation: FITL stands for Fiber In The Loop. It is a system used to upgrade PSTN (Public Switched Telephone Network) network Local loop. PSTN consists of all circuit-switched telephone in the whole world.

7. Adding bits to synchronize one digital signal to another is called _________
a) WDM
b) TDM
c) Bit stuffing
d) Bit synchronization

Explanation: Bit stuffing is the addition of bits for synchronization of one digital signal to another. It is mainly used in the transmission process of the network and communication protocols.

8. What is represented by “Figure Of Merit”?
a) how much noise is in the channel
b) how much noise is in the communication system
c) how much noise an amplifier adds to the signal
d) signal to noise ratio in dB

Explanation: Figure Of Merit is a measure of efficiency or effectiveness. It basically represents that how much noise is being added by an amplifier to the signal. However, the signal to noise ratio is the measure of the amount of signal present with respect to the surrounding noise.

9. In a balanced mixer, the output _________
a) contains equal amount of all input frequencies
b) does not contain the input frequencies
c) contains the input frequencies
d) is a non-linear mixture of input signals

Explanation: Mixer is a device that multiples two signals. In a balanced mixer, the output does not contain the input frequencies. And if it contains the frequency then mixer becomes imbalanced.