GROL Aviation Radio and Navigation Aids

Question 1

Which frequency range is used for VHF aeronautical voice communications such as air traffic control?

Accepted Answer

118–137 MHz

Answer

VHF aeronautical voice communication uses 118–137 MHz. 108–118 MHz is for navigation aids such as VOR and ILS localizers. 88–108 MHz is FM broadcast, and 156–162 MHz is marine VHF.

Question 2

What type of modulation do VHF aeronautical voice transmissions use?

Accepted Answer

Double-sideband amplitude modulation (A3E)

Answer

VHF airband voice uses double-sideband AM (A3E). With AM, two stations transmitting at once can both be heard instead of one blocking the other, as can happen with FM capture effect.

Question 3

In which frequency range does a VOR (VHF Omnidirectional Range) ground station operate?

Accepted Answer

108.00–117.95 MHz

Answer

VORs operate between 108.00 and 117.95 MHz and give the aircraft a bearing to or from the station. 190–535 kHz is NDB, 329–335 MHz is ILS glide slope, and 960–1215 MHz is DME.

Question 4

Which part of an Instrument Landing System (ILS) gives vertical guidance and operates in the UHF band?

Accepted Answer

Glide slope

Answer

The glide slope transmits in about 329–335 MHz (UHF) and gives vertical, descent-path guidance. The localizer gives lateral guidance in the 108–112 MHz VHF band.

Question 5

On what frequency do ILS marker beacons (outer, middle and inner) transmit?

Accepted Answer

75 MHz

Answer

All ILS marker beacons transmit straight up in a fan pattern on 75 MHz. They are told apart by their audio tone and keying pattern.

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Aviation Radio and Navigation Aids