Vayudoot Aviation

1. Which statement is true?

None of the above options are true.

The ionosphere will attenuate and refract signals up to 30 GHz.

The lower the frequency the greater the ionospheric attenuation.

The attenuation of an HF ground wave is worse over the land than over ice.

2. The term Doppler shift refers to?

The change in angle measured at the receiver.

The change in frequency measured at the receiver.

The change in depression angle measured at the receiver.

The change in speed measured at the receiver.

3. The approximate maximum range of ground waves of LF and MF are (by day) ..... and .....respectively, with..... suffering more from atmospheric attenuation?

1500 nm, 1000nm, MF.

1000 nm, 500nm, LF.

1000 nm, 300nm, MF.

500 nm, 100nm, LF.

4. The Instrument Landing System (ILS) uses the following wavelengths?

Hectometric

Decimetric

Centimetric

Metric

5. Assuming a wavelength of 1 centimetre, the frequency will be?

0.3 GHz.

3.0 GHz.

30 MHz.

30 GHz.

6. The emission characteristics A3E describe?

VOR

HF communications

ILS

VHF communications

7. The VHF frequency band has a wavelength limit of?

100 cm to 10 cm.

1 m to 100 cm.

100 m to 10 m.

10 m to 1 m.

8. When an LF radio wave passes over the Earth's surface it?

Slows down and is attenuated.

Speeds up, picks up electrons and becomes stronger.

Slows down, picks up electrons and becomes stronger.

Speeds up and is attenuated.

9. An HF transmitter is tuned to a frequency that refracts from the E layer in the ionosphere. The maximum distance of the first returning sky wave is?

1500 km.

599 km.

1500 nm.

599 nm.

10. A half wave dipole aerial suitable for transmitting an RF signal at 18 MHz should have an effective length of?

8.33 metres

16.67 metres.

83.33 metres

166.67 metres.

11.
In the diagram, the phase difference between the two signals is?

90 degrees

270 degrees.

180 degrees

360 degrees

12. What is the frequency corresponding to a wavelength of 12 centimetres is?

3600 MHz.

2500 kHz

360 MHz.

2500MHz.

13. Electromagnetic waves travel at?

300 000 metres per second

The speed of light

The speed of sound

162 000 miles per hour.

14. According to ICAO Annex 10, in which frequency band(s) does a locator transmit?

LF/MF

MF/HF

HF/VHF

HF

15. A wavelength of 8.5 metres corresponds to a frequency of?

28333 MHz.

3594.4 MHz.

2833.3 MHz.

35294 MHz.

16. Decimetric waves correspond to a frequency of?

300 to 3000 MHz.

3000 to 30000 kHz.

3000 to 30000 MHz.

300 to 3000 kHz.

17. Feeder lines are of the following types?

Co-axial-up to 3000 MHz, wave guides- above 3000 MHz.

Co-axial- above 3000 MHz, wave guides- up to 3000 MHz.

Wave guides - up to 20 MHz, co-axial-above 20 MHz.

Co-axial-up to 300 kHz, wave guides- above 300 kHz.

18. The frequency band for the Automatic Direction Finder (ADF) is?

Centimetric

Metric

Hectometric

Decimetric

19. Skip distance is the?

Wavelength distance of a certain frequency

Thickness of the ionosphere.

Range from the transmitter to the first returning sky wave.

Highest critical frequency distance

20. The Marker beacons use the following wavelengths?

Centimetric

Metric

Hectometric

Myriametric

21. Complete the following statement. .....radio signals have a ..... range by ..... wave over ..... than over .....?

MF, greater, ground, sea, land.

VHF, shorter, sky, sea, land.

MF, greater, ground, land, sea.

MF, shorter, sky, sea, land.

22. Diffraction is the process by which?

A direct wave is bend around the form of the Earth.

Radio waves travel over and around objects.

A space wave penetrates the ionosphere.

A ground wave is attenuated over rough ground.

23. A transmission of RF energy at a wavelength of 18 metres is in which frequency band?

VHF

MF

HF

LF

24. An aircraft travelling at 300 metres per second transmits a radio signal at 10 GHz to a stationary receiver. If the aircraft is flying directly towards the receiver and they are approximately at the same height, the received signal frequency will be?

11 MHz.

11 GHz.

10.000011 GHz.

9.999989 GHz.

25. Using a medium frequency band when is fading likely to occur?

Day with sky and ground waves.

Day time when snowing.

Night with sky and ground waves.

night time when snowing.

26. The wavelength of a radio signal transmitted at a frequency of 118.7 MHz?

2.53 metres.

25.3 centimetres

25.3 metres

2.53 centimetres

27. MF fading is most common?

At night and during heavy rain.

During the day and during heavy rain.

During the day due to the reception of both sky waves and ground waves.

At night due to the reception of both sky waves and ground waves.

28. What is the wavelength of a radio signal with a frequency of 375 kHz?

80 metres

1.25 metres

800 metres

12.5 metres

29.
In the diagram below what is the phase difference of the higher amplitude signal from the reference signal?

225 degrees

045 degrees.

315 degrees

135 degrees.

30. What is the wavelength of a VOR?

Decimetric

Hectometric

Metric

Centimetric

31. The VHF Direction Finder uses the following wavelengths?

Metric

Centimetric

Decimetric

Hectometric

32. A radio signal has a frequency of 3 GHz, What is its wavelength?

1.0 centimetres.

10 centimetres.

100 centimetres.

1 metres

33. When a transmitter is moving towards a receiver, the correct description of Doppler effect is?

There is a decrease in apparent wavelength , which is independent of transmitter velocity.

There is a decrease in apparent wavelength, which is dependent of transmitter velocity.

There is an increase in apparent wavelength, which is independent of transmitter velocity.

There is an increase in apparent wavelength , which is dependent of transmitter velocity transmitter velocity.

34. A radio signal loses strength as the range from the transmitter increases. This effect is called?

Amplification.

Refraction.

Attenuation.

Ducting.

35. The VHF frequency band is in the?

30 to 300 MHz range.

3 to 30 MHz range

30 to 300 kHz range.

3 to 30 kHz range.

36. The Microwave Landing System (MLS) uses the following wavelengths?

Centimetric

Myriametric

Hectometric

Metric

37. Refraction of an eletromagnetic radiation is?

Loss of power through reflection from objects.

Bending resultant from reflection from objects.

The loss of power as it passes through or over areas of different electrical conductivity.

The bending of its propagation path as it passes through or over areas of different electrical conductivity.

38. Which of the folllowing statements is correct in respect to a RF signal?

The magnetic component of the signal is parallel to the aerial.

Both the electrical component and the magnetic component of the signal are parallel to the aerial.

The electrical component of the signal is parallel to the aerial.

The plane of polarisation is dictated by the oscillator unit in the transmitter.

39. Reflection from the ionospheric layers is used in the following radio frequencies?

HF.

UHF.

VHF.

VLF.

40. A Doppler shift will occur?

If a receiver is moving during reception of transmission from a fixed position transmitter.

When the distance between a transmitter and a receiver is changing during a transmission.

If a transmitter is moving during transmission to a fixed position.

All of the options are correct.

41. The wavelength of a radio signal is 200 metres. What is its frequency?

1.5 GHz.

15 MHz.

1.5 kHz.

1.5 MHz.

42. What is the wavelength corresponding to a frequency of 375 kHz?

8 metres

8000 metres.

80 metres

800 metres

43. Which of the following statements is true?

Bandwidth must be reduced in order to reduce noise.

A narrow bandwidth improves beam width.

A transmission's bandwidth is affected by the design of the aerial.

A broad bandwidth gives a narrow beam width.

44. The gain of an aerial is its ability to?

Transmit intelligence.

Compensate for attenuation

Overcome transmitter line resistance

Focus power

45. What is the wavelength corresponding to a frequency of 75 MHz?

7.5 metres.

40 metres.

4 metres.

75 metres.

46. In the propagation of MF waves, the phenomenon of FADING is particularly found?

By day due to the combination of sky waves and ground waves.

By day and when raining.

At night and when raining.

At night, due to the combination of sky waves and ground waves.

47. A horizontally polarised electromagnetic wave?

Has the H field horizontal.

Has the E field vertical

Has the E field horizontal.

Has the Z field horizontal

48. A frequency of 2400 kHz is equivalent to a wavelength of?

0.8 metres

105 metres

8 metres.

125 metres

49. The Secondary Surveillance Radar (SSR) uses the following wavelengths?

Hectometric

Decimetric

Myriametric

Centimetric

50. Fading happens?

At daytime when the signal is received by sky waves only.

At night when the signal is received by ground waves only.

At night when ground waves and sky waves interfere with each other.

In daytime when ground waves and sky waves interfere with each other.

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