Vayudoot Aviation

1. The process which causes the reduction in signal strength as range from a transmitter increases is known as

diffraction

ionisation

attenuation

absorption

2. The maximum range an aircraft at 2500 ft can communicate with a VHF station at 196 ft is

64 nm

80 nm

65 nm

52 nm

3. Concerning HF communications, which of the following is correct?

At night a higher frequency is required than by day.

The frequency required for short ranges will be less than the frequency required for long ranges.

The frequency required in low latitudes is less than the frequency required in high latitudes.

The frequency required is dependent on time of day but not the season.

4. A 300 kHz transmitter has an output of 1600 watts, the effective range over the sea will be

80 nm

35 nm

120 nm

52 nm

5. Determine which of the following statements concerning atmospheric ionisation are correct. 1. The highest levels of ionisation will be experienced in low latitudes. 2. Ionisation levels increase linearly with increasing altitude. 3. The lowest levels of ionisation occur about midnight. 4. The E-layer is higher by night than by day because the ionisation levels are lower at night.

statements 1, 3 and 4 are correct

statements 1, 2 and 3 are correct

statements 1 and 4 are correct

statements 2 and 4 are correct

6. It is intended to increase the range of a VHF transmitter from 50 nm to 100 nm. This will be achieved by increasing the power output by a factor of

4

8

16

2

7. Which of the following will give the greatest surface wave range?

500 kHz

2182 khz

243 MHz

15 MHz

8. What is the minimum height for an aircraft at a range of 200 nm to be detected by a radar at 1600 ft amsl?

57,500 ft

15,000 ft

25,500 ft

40,000 ft

9. The average height of the E-layer is …… and the maximum range for skywave will be ……

225 km, 2200 km

60 km, 1350 nm

125 km, 1350 nm

125 km, 2200 km

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