Communication system Revision 39-40

Visible light has a frequency of approximately 5.0 × 10¹⁴ Hz. M and N are two other types of electromagnetic radiation. The frequency of M is 5.0 × 10⁶Hz.

The frequency of N is 5.0 × 10¹⁵Hz. Which types of radiation are M and N?

• A

• B

• C

• D

An electronic engineer makes devices which can receive television pictures from satellites.

Which type of electromagnetic radiation must these devices be able to receive?

• infra-red waves

• microwaves

• radio waves

• ultra-violet waves

Which group of electromagnetic radiations is arranged in order of increasing frequency?

• infra-red, visible light, ultraviolet

• γ-rays, X-rays, infra-red

• ultra-violet, visible light, radio waves

• X-rays, radio waves, γ-rays

A carrier wave of frequency 300kHz and amplitude 5.0V is frequency modulated by a sinusoidal signal of frequency 6kHz and amplitude 2.0V. The frequency deviation of the carrier wave is 30 kHzV^-1. Determine the max. frequency

• 360 kHz

• 330 kHz

• 420 kHz

• 450 kHz

Choose a properties of FM:

• Less prone to interference

• Greater area covered

• Higher spectrum from 88 to 108 MHz or 1200 to 2400 bits per second

• Ranges from 535 to 1705 kHz

Determine the maximum frequency of the transmitted audio signal

• 18 kHz

• 9 kHz

• 918 kHz

• 909 kHz

The properties of digital signal

• Denoted by sine waves

• Denoted by square waves

• Continuous signal

• Discrete signal

If we have 4 bit system, how many voltage level in communcation system?

• 8

• 16

• 32

• 256

Energy loss in wire because of ...

• electrical heating

• absorption

• scattering

_________ - is the gradual decrease in the power of a signal the further it travels.