﻿ Amplitude modulation has | Communication Systems

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# Communication Systems

#### Multiple Choice Questions

41.

A signal wave of frequency 12 kHZ is modulated with a carrier wave of frequency 2.51 MHz. The upper and lower side band frequencies are respectively

• 2512 kHz and 2508 kHz

• 2522 kHz and 2488 kHz

• 2502 kHz and 2498 kHz

• 2522 kHz and 2498 kHz

42.

The range of frequencies allotted for FM radio is

• 88 to 108 kHz

• 88 to 108 MHz

• 47 to 230 kHz

• 47 to 230 MHz

43.

If a radio receiver amplifies all the signal frequencies equally well, it is said to have high

• fidelity

• distortion

• sensibility

• sensitivity

44.

A TV tower has a height of 100 m. What is the maximum distance up to which the TV transmission can be received (R = 8 × 106 m) ?

• 34.77 km

• 32.70 km

• 40 km

• 40.70 km

# 45.Amplitude modulation hasone carrier with infinite frequencies one carrier with two side band frequencies one carrier with high frequency one carrier

B.

one carrier with two side band frequencies

Amplitude modulation has one carrier with two side band frequencies. The AM wave contains three frequences fc (fc + fm) and (fc − fm) fc is called carrier frequency, (fc + fm) is upper side band (USB frequency) and (fc − fm) is lower side band frequency.

46.

The waves used for Line-of-Sight (LOS) communication is

• sound waves

• ground waves

• sky waves

• space waves

47.

The process of superimposing message signal on high frequency carrier wave is called

• amplification

• demodulation

• transmission

• modulation

48.

A basic communication system consists of

1. Transmitter
2. Information sources
3. User of information
4. Channel