GROL Aviation Radio and Navigation Aids 5

Question 1

What modulation is used for VHF aeronautical voice communications in the 118-137 MHz band?

Accepted Answer

Amplitude modulation (AM)

Answer

Aviation VHF voice uses double-sideband AM, allowing a stronger signal to be heard over a weaker one.

Question 2

What is the international aeronautical emergency frequency monitored by ELTs and aircraft?

Accepted Answer

121.5 MHz

Answer

121.5 MHz is the VHF aeronautical emergency frequency and the ELT homing signal frequency.

Question 3

Modern ELTs transmit a digitally encoded distress message for satellite detection on which frequency?

Accepted Answer

406 MHz

Answer

406 MHz ELTs send coded messages to Cospas-Sarsat satellites, with 121.5 MHz used for homing.

Question 4

Which transponder code indicates an aircraft is experiencing a general emergency?

Accepted Answer

7700

Answer

Squawk 7700 signals an emergency; 7600 is radio failure and 7500 is unlawful interference.

Question 5

What type of emission is typically used for long-range HF aeronautical communications over oceans?

Accepted Answer

Single sideband suppressed carrier (J3E)

Answer

HF aeronautical mobile service uses upper sideband SSB voice for efficient long-range communications.

(GROL) General Radiotelephone Operator License Practice Test