02 Communication Methods

Question 1

The VHF Spectrum?

Answer 1

The radio frequency spectrum is part of the electromagnetic spectrum. The VHF spectrum spans all the frequencies from 30 to 300 MHz

Question 2

The air band range?

Answer 2

The air band is the range of VHF frequencies spanning 108-137 MHz.

Question 3

Location of the HF band?

Answer 3

The HF frequency band sits below VHF. The UHF frequency band sits above the VHF band in the radio spectrum.

Question 4

The minimum seperation between frequencies in the air band?

Answer 4

The minimum separation between useable frequencies in the air band is 8.33 kHz.

This used to be 25kHz

If you don’t have 8.33 radio, you should say ‘negative 8.33’

Question 5

Uses of VHF?

Answer 5

VHF radio, VDF, VOR, Marker Becon and ILS

Question 6

The four factors which reduce the effective range and quality of VHF radio transmissions ar

Answer 6

• Line of sight requirement.
• Curvature of the Earth.
• Atmospheric electromagnetic interference.
• Power of the transmitter.

Question 7

Frequency bands?

Answer 7

Frequency ranges increase by a factor of 10.

Question 8

How to remember EM spectrum?

Answer 8

Very
Lovely
Maidens
Have
Very
Useful
Sewing
Bands

Question 9

Air-ground communication?

Answer 9

Two-way communication.

Question 10

Air-to-ground communication?

Answer 10

One-way communication

Question 11

Equation for Wavelength?

Answer 11

c = λF

c = 3 x 10^8

Question 12

Blind transmission?

Answer 12

A transmission where two-way communication cannot be established but where it is believed that the called station can receive.

Question 13

Broadcast?

Answer 13

A transmission not addressed to a specific station or stations.

Question 14

Duplex?

Answer 14

Communication which can take place in both directions simultaneously

Question 15

Ground-to-air communication.

Answer 15

One-way communication

Question 16

Interpilot air-to-air communication?

Answer 16

Two-way communication between aircraft.

Question 17

Non-network communications?

Answer 17

Radiotelephony communications outside the normal lines of a radiotelephony network?

Question 18

Radiotelephony network?

Answer 18

Radiotelephony network. A group of radiotelephony aeronautical stations

Question 19

Readback?

Answer 19

A procedure whereby the receiving station repeats a received message.

Question 20

Simplex?

Answer 20

Communication takes place in one direction at a time.

Question 21

Air/Ground Radio?

Answer 21

Not run by qualified personel.

Question 22

Telecommunication?

Answer 22

Any transmission, emission, or reception of signs, signals, writing, images and sounds or intelligence of any nature by wire, radio, optical or other electromagnetic systems.”

Question 23

Modulation used for VHF?

Answer 23

AM modulated

Question 24

Identifying AC modualtion issues?

Answer 24

Carrier wave + voice = full RT heard
Carrier wave + no info = static noise heard.

If you just hear a click, or static, this means just the carrier is being transmited, no modulation is occuring.

Question 25

What frequencies are more likly to be effected by static and noise?

Answer 25

The lower the frequency the more likly to be effected by static and noise.

Question 26

How is radio range effected?

Answer 26

Transmit power
R~sqrt(Power)

Doubling the range needs 4 times the power

Question 27

Super refraction?

Answer 27

Inversions can create a ducting to allow the passesage of energy.

VHF range increases substantially beyond the LOS

Question 28

Attenuation?

Answer 28

The loss of energy.

Question 29

What increases attenuation?

Answer 29

• Higher frequencies / shorter wavelength
• Increased air density / decreased temperature.

Therefore least attenuation occurs between aircraft at higher frequencies.

Question 30

Phase differnece?

Answer 30

A phase differnece can cause fading of a signal.

Question 31

Max Theoretical Range Equation?

Answer 31

Max Theoretical Range (nm) = 1.23 (sqrt(Tx)+sqrt(Rx))

Tx = the elevation of the transmitter (feet AMSL)
Rx = the elevation of the reciever (feet AMSL)