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BTC 3/24 - EQPS > EQPS - Radio Theory > Flashcards

EQPS - Radio Theory Flashcards

1
Q

What use of radio is in ATC? (5)

A
  1. Voice Communication VHF/ UHF
  2. Navigation VOR /NDB
  3. Surveillance systems
  4. Weather radar
  5. Data transmission
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2
Q

What is Electricity? (1)

A

A form of energy produced by the movement of electrons in
atoms

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3
Q

What is Electro-magnetism? (1)

A

An electric current produces a magnetic field (B) perpendicular to the flow direction (I)

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4
Q

What are Radiowaves? (7)

A
  1. A form of electromagnetic energy that are similar in behavior to light waves
  2. Travel at 300,000,000 meters p/s (C)
  3. Can pass through a vacuum
  4. Travel in straight lines
  5. Invisible
  6. Intangible
  7. Inaudible without specialist equipment
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5
Q

What is Oscilation? (1)

A

When air moves backwards/forward (vibration) and the ear mimics the air which is moving. The receiving person hears a propagated tone

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6
Q

What is Audio limited by? (1)

A

Range

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7
Q

What is a Sine Wave? (1)

A

When a wave travels up, down and back to Zero - This is 1 cycle

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8
Q

What is Amplitude? (1)

A

The maximum displacement or value attained by the wave from it’s mean value during a cycle

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9
Q

What is Wavelength? (1)

A

The distance in meters or part of a meter between corresponding points in consecutive waves (Lambda ƛ)

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10
Q

What is Frequency? (1)

A

The rate of repetition of the cycle in one second where one cycle per second is known as one Hertz

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11
Q

How many Hertz in:
Kilohertz, Megahertz, Gigahertz

A

Kilohertz - 1Khz = 1000 Hz
Megahertz - 1 Mhz = 1,000,000 hz
Gigahertz - 1 Ghz = 1,000,000,000 Hz

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12
Q

What is Velocity (C)?

A

A constant electromagnetic wave at 300,000,000 meters p/s in a Vacuum

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13
Q

How do we get a lower frequency? (1)

A

A longer wavelength

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14
Q

How do we get a Higher frequency? (1)

A

A Shorter wavelength

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15
Q

What is the formula for calculating Velocity (C)? (1)

A

Frequency x Wavelength

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16
Q

What is a Carrier wave? (1)

A

An electro-magnetic wave which can be
modulated (varied) and is produced by a device called “The Local Oscillator”

17
Q

How does Modulation work? (1)

A

When a carrier wave is varied in direct proportion to the signal that is to be transmitted…

…Modulation can change the amplitude or frequency of the carrier wave

18
Q

How is a Carrier Wave modulated? (1)

A

Audio signal fed into a Modulator…

…Combines the carrier wave with the audio wave

19
Q

What does FM stand for? (1)

A

Frequency Modulation

20
Q

What does AM stand for? (1)

A

Amplitude Modulation

21
Q

AM Modulation Diagram

A
22
Q

FM Modulation Diagram

A
23
Q

What are the Advantages of FM? (3)

A
  1. Resillience to noise
  2. Easy to apply modulation at a low power
  3. Use of efficient RF amplifiers
24
Q

What are the Advantages of AM? (2)

A
  1. Stronger stations can override weaker / interfering stations
  2. A squeal (Heterodyne) will be heard > if both Tx’s are received with identical signal strength
25
Q

What type of wave is sent to an Antenna? (1)

A

A Modulated carrier wave

26
Q

What is a half-wave aerial? (1)

A

When using the top of a positive part of a cycle (Using a portion of the Wavelength)

e.g. small A/C aerials

27
Q

What happens when you halve the wavelength? (1)

A

Power must be doubled to get the same range

28
Q

How does EMF radiate? (1)

A

Perpendicular to the atenna

Vertical Antenna = Horizontal EMF
Horizontal Antenna = Vertical EMF

29
Q

What does the RF AMP do? (2)

A
  1. Makes signal stronger
  2. Amplifies static noise (Consequence)
30
Q

What is Static filtered out by? (1)

A

Noise Gate

31
Q

What does a Demodulator do? (2)

A
  • Earth’s out the carrierwave
  • Audio part remains > fed into an audio amplifier
32
Q

What happens to the signal when fed into an Audio Amplifier? (3)

A
  • Signal fed into coil of wire around speaker magnet
  • Diaphragm moves > air displaced to/from original frequency & amplitude
  • Original sound is heard

BTC 3/24 - EQPS (12 decks)

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