AET Communication Systems

Question 1

What frequency band does aviation VHF communication primarily use?

Accepted Answer

118–137 MHz

Answer

Aviation VHF communications operate in the 118.000–136.975 MHz frequency band for air-to-ground and air-to-air voice communications.

Question 2

What modulation type is used by VHF aviation voice communication radios?

Accepted Answer

AM

Answer

VHF aviation communications use Amplitude Modulation (AM) because it allows simultaneous reception from multiple stations and simulates 'breaking squelch' when multiple transmitters key at once.

Question 3

What is the channel spacing used by modern 8.33 kHz VHF aviation radios in Europe?

Accepted Answer

8.33 kHz

Answer

Europe mandates 8.33 kHz channel spacing to increase frequency spectrum capacity in congested airspace.

Question 4

Which component in a VHF comm transceiver ensures the carrier frequency is stable?

Accepted Answer

Frequency synthesizer with PLL

Answer

A frequency synthesizer using a Phase-Locked Loop (PLL) generates precise, stable carrier frequencies across all selectable channels.

Question 5

What is the purpose of a squelch circuit in an aviation receiver?

Accepted Answer

Mute the receiver when no signal is present

Answer

The squelch circuit silences the audio output when received signal strength falls below a set threshold, eliminating background noise between transmissions.

(AET) Aircraft Electronics Technician Practice Test

(AET) Aircraft Electronics Technician Practice Test

AET Communication Systems