BASIC RADIO THEORY: DGCA Air Navigation questions

Question 1

In an amplitude modulated signal, the amplitude of the carrier wave will:

Accepted Answer

vary according to the amplitude of the modulating signal.

Answer

remain constant, and the frequency will vary according to the amplitude of the modulating signal.

Answer

vary according to the frequency of the modulating signal.

Question 2

To establish and maintain effective HF communications, the frequency used for a given range:

Accepted Answer

should be decreased at night.

Answer

should remain constant.

Answer

should only be varied by season, decreased in summer and increased in winter.

Question 3

For a given set of ionosphere conditions, as the frequency of an HF signal is increased:

Accepted Answer

the size of the dead space increases due solely to the increasing minimum skip distance.

Answer

the size of the dead space increases due solely to the decreasing minimum skip distance.

Answer

the size of the dead space decreases because the surface wave coverage decreases and the minimum skip distance decreases.

Question 4

Around a radiating transmitter aerial there is:

Accepted Answer

an electrical and magnetic field.

Answer

a magnetic field.

Answer

an electrical field.

Question 5

The rate of attenuation of a radio wave which occurs when the wave travels close to the Earth's surface.

Accepted Answer

increases as the frequency of the wave increases, and is greater over the sea than the land.

Answer

decreases as the frequency of the wave increases, and is greater over the land than the sea.

Answer

decreases as the frequency of the wave increases, and is greater over the sea than the land.

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