EQPS

Question 1

Sound waves travel at what speed?

Answer 1

The speed of sound

Question 2

Radio waves travel at what speed?

Answer 2

The speed of light

Question 3

What allows radiowaves to travel so far without attenuating?

Answer 3

The are part of the electromagnetic spectrum and therefore do not require a medium to travel through

Question 4

What does attenuation mean?

Answer 4

Weakening of waves

Question 5

What is a wavelength?

Answer 5

Measurement of a wave from crest to crest

Question 6

What is frequency?

Answer 6

Number of times a wave oscillates per second

Question 7

If frequency and wavelength are inversely proportional, then a high frequency will mean?

Answer 7

Short wavelength.

Question 8

What travels further, high frequency or low frequency?

Answer 8

Low frequency. The wavelengths are longer and therefore less susceptible to attenuation.

Question 9

Outline the process of a basic radio transmission?

Answer 9

MICROPHONE detects small audio waves, OSCILLATOR creates a basic carrier wave. MODULATOR superimposes audio wave onto carrier wave. TRANSMITTER sends the radio signal. It is received by the receiving antenna, demodulated and amplified via the speaker.

Question 10

What are the 4 methods of modulation?

Answer 10

Keying, Pulse modulation, Amplitude modulation, Frequency modulation.

Question 11

In general civil ATC, HF, VHF and UHF are used for what purposes?

Answer 11

HF - Oceanic RT
VHF - RT between ATC and a/c
UHF - use on ground between ATC and vehicles

Question 12

What are the emergency frequencies that are constantly monitored?

Answer 12

121.5 and 243.0 VHF.

Question 13

Name 4 Navaids that use radiowaves in aviation?

Answer 13

VOR, DME, ILS, NDB

Question 14

What is propagation?

Answer 14

The behaviour of radiowaves when they are transmitted from one point to another or in the atmosphere.

Question 15

Name some methods of propagation experienced by radiowaves?

Answer 15

Reflection, refraction, diffraction, attenuation, absorption.

Question 16

State the difference between skywaves and groundwaves?

Answer 16

skywaves are refracted by Ionosphere and redirected back to Earth’s surface, whereas groundwaves follow a parallel path to Earth’s surface.

Question 17

What is the purpose of a repeater station?

Answer 17

As ground waves travel in a ‘line of sight’ path, repeater stations can help to increase range.

Question 18

State the Ionospheres effect on skywaves?

Answer 18

During the day, the ionosphere is excited by the suns radiation, leading to increased absorption of skywaves. At night the ionosphere contracts leading to increased reflection.

Question 19

HF & NDB signals suffer from some forms of interference. Name them?

Answer 19

Static interference, station interference, night effect.

Question 20

Explain antenna shadowing.

Answer 20

As the aircraft turns, some parts of the airframe block the antenna. less apparent in modern planes that have multiple antenna.

Question 21

What is a VDF?

Answer 21

VHF Direction Finder. Uses radio transmissions of an aircraft to determine the aircraft’s bearing from the station.

Question 22

What is VCCS?

Answer 22

Voice Communications Control System. Connects various systems for ATC communications and merges them onto the same software/interface.

Question 23

What is Selcal?

Answer 23

Sends 2 two-tone consecutive signals on a list of frequencies that chimes in the cockpit. Saves the pilot from having to listen continuously to noisy frequencies.

Question 24

What is ACARS?

Answer 24

Aircraft Communications Addressing and Reporting System. Airline to aircraft communications. Broadly 3 types: ATC messages, Aeronautical operational control, airline administrative control.

Question 25

What frequencies does civil aviation use?

Answer 25

118-137 Mhz VHF frequencies.

Question 26

What is AMS?

Answer 26

Aeronautical Mobile Service. Dedicated frequencies communications system for emergencies and instances related to the safety and regularity of flights.