What is the maximum limit on the frequency that can be used for ground wave communication?

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

3MHz

5MHz

6MHz

7MHz

Correct Answer : 3MHz

Explanation : Up to 3MHz, an appreciable amount of energy follows the curvature of the earth and are called as the ground wave. Above 3MHz, the radio waves do not follow the curvature of the earth and are used for a line of sight communication.

Recently Updated in Avionics Questions

Which of the following type is not used in an Omega system?

Valley span

Insulated tower

Hanging tower

Grounded tower

Correct Answer : Option (C) : Hanging tower

Explanation : Since the Omega stations transmit in very low frequencies, the antennas are the largest physical structures in the stations. Three types of antennas are employed in the Omega system: grounded tower, insulated tower, and the valley span.

_____ acts as a coarse tuning device for the antenna?

Loop

Helix

Filters

Amplifiers

Correct Answer : Option (B) : Helix

Explanation : The RF signal that is to be transmitted is transferred to the ‘Helix,’ a large helical coil that acts as a coarse tuning device for the antenna. The helix is equipped with separate taps for each signal frequency transmitted.

What type of transmission is used in Omega system?

Phase modulated wave

Continuous wave

Amplitude modulated wave

Frequency modulated wave

Correct Answer : Option (B) : Continuous wave

Explanation : At each Omega station, continuous wave signals on four common frequencies and one station unique frequency. The signal frequencies are time shared among the stations so that a given frequency is transmitted by only one station at any given time.