Vayudoot Aviation

1. In regard to radio what does the term frequency mean?

The number of waveform in one hour.

The length of a complete waveform in metres.

The number of complete waveform passing a point in one second

The speed of radio waves in metres per second

2. The skip distance of HF transmissions will increase with?

Higher frequency and lower position of the reflecting layer.

Lower frequency and lower position of the reflecting layer.

Higher frequency and higher position of the reflecting layer.

Lower frequency and higher position of the reflecting layer.

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

80 metres

800 metres

1.25 metres

12.5 metres

4. SELCAL is an equipment that?

Is coupled with TCAS II and is concerned with TA warnings systems.

Automatically transmits data signals.

Functions as a frequency modulator.

Automatically receives incoming signals

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

800 metres

8000 metres.

80 metres

8 metres

6. Wavelength is the distance from?

Wave crest to wave crest

Wave crest to next trough.

The E and H fields superimposed onto the system reactance background scatter

Trough to next wave crest

7. The frequency at which sky waves should least affect reception?

MF.

LF.

VLF.

HF

8. A horizontally polarised electromagnetic wave?

Has the H field horizontal.

Has the Z field horizontal

Has the E field vertical

Has the E field horizontal.

9. Skip distance is the?

Thickness of the ionosphere.

Wavelength distance of a certain frequency

Range from the transmitter to the first returning sky wave.

Highest critical frequency distance

10. Comparing a parabolic reflector with a flat plate antenna of the same size?

The flat plate antenna generates less side lobes than the parabolic reflector

The flat plate has a considerably smaller beam width

The parabolic reflector generates less side lobes that the flat plate antenna.

The parabolic reflector has a considerably smaller beam width

11. Attenuation of a radio wave is the?

Change of amplitude by use of sidebands.

Change of its frequency by use of sidebands.

Reduction of its power by absorption, scattering or spreading.

Increase of its power by the combination of multi-path signals.

12. Assuming a frequency of 20 MHz, the wavelength will be?

800 metres

80 metres

1.25 metres.

12.5 metres

13. The VHF frequency band is in the?

3 to 30 MHz range

30 to 300 kHz range.

30 to 300 MHz range.

3 to 30 kHz range.

14. Decimetric waves correspond to a frequency of?

300 to 3000 MHz.

300 to 3000 kHz.

3000 to 30000 MHz.

3000 to 30000 kHz.

15. The Marker beacons use the following wavelengths?

Myriametric

Hectometric

Metric

Centimetric

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

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

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

17. Refraction of an eletromagnetic radiation is?

Bending resultant from reflection from objects.

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

Loss of power through reflection from objects.

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

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

Decimetric

Metric

Centimetric

Hectometric

19. The wavelength of a non-directional beacon (NDB) at a frequency of 300 kHz is?

1000 metres

100 metres

10 metres

1 metres

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

3600 MHz.

360 MHz.

2500MHz.

2500 kHz

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

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

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

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

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

22.
At night due to the reception of both sky waves and ground waves.

Increase.

Decrease by night only.

Decrease.

Increase over the sea.

23. Fading happens?

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

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

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

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

24. Diffraction is the process by which?

A space wave penetrates the ionosphere.

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

Radio waves travel over and around objects.

A ground wave is attenuated over rough ground.

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

1 metres

100 centimetres.

1.0 centimetres.

10 centimetres.

26. Which of the following statements is true?

A narrow bandwidth improves beam width.

A broad bandwidth gives a narrow beam width.

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

Bandwidth must be reduced in order to reduce noise.

27. The Low Altitude Radio Altimeter (RADALT) uses the following wavelengths?

Metric

Centimetric

Decimetric

Myriametric

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

HF

MF

LF

VHF

29. Into what range does ILS localiser wavelength fall?

Metric

Kilometric

Nanometric

Millimetric

30. What is the lowest frequency where freedom from static interference can be guaranteed?

300 MHz.

30 MHz.

3 MHz.

3 GHz.

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

125 metres

8 metres.

105 metres

0.8 metres

32. Diffraction of an FR signal is a displacement of its propagation path due to?

Passing over obstacle with dimensions close to the wavelength.

Reflection from the surface.

Passing through ionised regions of the upper atmosphere.

Passing over or through mediums of different conductivity.

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

1000 nm, 300nm, MF.

1500 nm, 1000nm, MF.

500 nm, 100nm, LF.

1000 nm, 500nm, LF.

34. The emission characteristics A3E describe?

VHF communications

HF communications

ILS

VOR

35. To establish and maintain effective HF communication, frequency at a given range?

Should be decreased at night.

Should be increased at night.

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

Should remain constant.

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

Myriametric

Metric

Hectometric

Centimetric

37. What is the wavelength of a VOR?

Decimetric

Metric

Hectometric

Centimetric

38. The wavelength of a radio signal with a frequency of 121.95 MHz?

2.46 metres.

26.60 metres.

2.46 centimetres

24.60 centimetres

39. A radio transmitter modulator?

Superimposes an audio frequency signal (AF) onto a radio frequency signal (RF).

Tunes the aerial only

Couples the RF signal to an aerial

Ensures receiver compatibility

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

UHF.

VHF.

HF.

VLF.

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

40 metres.

7.5 metres.

75 metres.

4 metres.

42. 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.

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

28333 MHz.

2833.3 MHz.

35294 MHz.

3594.4 MHz.

44.
In the diagram, the phase difference between the two signals is?

360 degrees

270 degrees.

180 degrees

90 degrees

45. What is the wavelength of the ILS Localiser signal?

Myriametric

Centimetric

Hectometric

Metric

46. Which statement is true?

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

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.

47. A Doppler shift will occur?

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

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

All of the options are correct.

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

48. Frequency is define as the?

Distance between a crest and a crest

Number of complete cycles recurring in one unit of time.

Distance from axis to peak value

Number of complete cycles recurring in ten units of time

49. A radio facility transmits on a wavelength of 2.22 cm. The facility could be a ............. operating on a frequency of ........?

Doppler 13500 MHz.

DME, 1350 MHz.

VDF, 135 MHz.

Radio Altimeter 13500 kHz.

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

100 m to 10 m.

100 cm to 10 cm.

1 m to 100 cm.

10 m to 1 m.

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