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IHTC > Avionics > Flashcards

Avionics Flashcards

1
Q

What is radio waves?

A

Electromagnetic oscillations (variants of electric and magnetic field)

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2
Q

Define amplitude

A

The magnetude of the change in the electric field intensity

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3
Q

Define frequency

A

Number of oscillations per second, measured in hertz

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4
Q

Define wave length

A

Distance between the beginning and the end of an oscillation in metres

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5
Q

What is the frequency spam for HF, VHF and UHF

A

HF = 3 MHz - 30 Mhz
VHF = 30 Mhz - 300 Mhz
UHF = 300 Mhz - 3 GHz

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6
Q

Different propagation

A

7 types

  • Reflection
  • Refraction
  • Diffraction
  • Dispersion
  • Absorption
  • Interference
  • Polarization
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7
Q

Define reflection

A

Waves reflected by the ionosphere, mountains, buildings, ground etc.

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8
Q

Define refraction

A

Change in speed and direction due to change in air density or conductivity.

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9
Q

Define diffraction

A

Bending of waves around obstacles

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10
Q

Define dispersion

A

Seperation of waves caused by particles in the air

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11
Q

Define Absorption

A

Electromagnetic energy is transformed to other forms of energy

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12
Q

Define Interference

A

Interaction of two waves which have the same source or nearly the same frequency. Either increase or decrease amplitude.

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13
Q

Define polarization

A

Change of orientation of the oscillation

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14
Q

Propagation types

A
  • Ground waves
  • Sky waves
  • Line of sight
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15
Q

Which propagation types does HF, VHF and UHF use?

A

HF = Generally sky waves
VHF/UHF = Line of sight

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16
Q

Types of modulation

A
  • amplitude modulation
  • frequency modulation
  • pulse modulation
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17
Q

Working principle of an NDB

A

A signal is sent out in all directions. In a 40 degree angle directly above is the cone of silence.

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18
Q

Onboard equipment with and NDB

A

ADF

  • Loop antenna (bidirectional) and sense antenna (non directional)
  • Receiver
  • Control panel
  • Indication instrument
19
Q

Errors regarding NDB

A
  • Differences in range
  • Fading
  • Twilight / night effect
  • Statics and thunderstorm effect
  • Mountain effect
  • Dip error
  • Shoreline effect
  • Quadrantal error
20
Q

NDB ERROR:
Define difference in range

A

Differences in range due to the surface as an example.

Countermeasure:
- always identify tuned in NDB

21
Q

NDB ERROR:
Define fading

A

Interference of radio waves (sky/ground)

Countermeasures:
- Use NDB within 30 nm
- Use low frequency NDBs

22
Q

NDB ERROR:
Define twilight / night effect

A

NDB waves are reflected by the ionosphere during sunset/at night.

Countermeasures:
- NDB within 30 nm
- NDB with low frequency

23
Q

NDB ERROR:
Define statics and thunderstorm effect

A

Electrons producing electrical fields interfering with the NDB signal.

Countermeasures:
- Turn off the instrument if possible

24
Q

NDB ERROR:
Define Mountain effect

A

Ground waves may change direction by diffraction.

Countermeasures:
- Higher altitude
- Check course with terrestrial navigation

25
Q

NDB ERROR:
Define dip error

A

The loop antenna is moved away from its minimum position due to banking in a turn.

26
Q

NDB ERROR:
Define shoreline effect

A

Change of electrical conductivity over water refracts waves passing the shoreline.

Countermeasures:
- Higher altitude
- NDB close to the shoreline

27
Q

Working principle of a VOR

A

Based on a lighthouse principle.

2 antennas:
- Reference antenna (non directional)
- Rotating antenna (directional)

Two signals are received and based on the phase shift, it calculates the radial you’re currently flying on.

28
Q

What does VOR stand for?

A

Very High frequency omnidirectional radio range

29
Q

Working principle of a DVOR?

A

A non directional signal is sent frem the middle of the station, surrounded by 36-50 non-directional antennas which are turned on one by one.

30
Q

Advantages of DVOR

A
  • No moving parts
  • Precision
  • Reduced reflection + refraction
31
Q

VOR onboard equipment

A
  • Antenna
  • Receiver
  • Control panel
  • Indication instrument
32
Q

Advantages of VOR

A
  • No dip error
  • No quadrantal error
  • Less statics
  • Less twilight effect
33
Q

ILS working principle

A

3 ground components:
- Localizer
- Glideslope antenna
- Marker beacons

Localizer transmits two different signals, 90 hz on the left side of runway and 150 hz on the right side of the runway. Both AM. The receiver on board compares the signals and give an indication if you’re on the centerline, or left/right.

Glide slope antenna produce two beams, a 90 hz above the glideslope and a 150 hz below. It’s the same principle as the localizer, but your indication is if you’re above or below the GS.

Marker beacon transmits three different audio signals. One for the outer, one for the middle, and one for the inner marker.

34
Q

ILS onboard equipment

A
  • ILS antenna
  • ILS receiver
  • ILS control panel
  • ILS indication instrument
35
Q

Working principle of the DME

A

The aircraft DME sends out pulse pairs, which are received by the DME ground station. The ground station will reply with the same unique pulses. The time it takes between these signals to get back, can determine the slant range distance to the DME in NM.

There can be up to 100 aircrafts working with an DME at the same time.

36
Q

DME onboard equipment

A
  • Receiver
  • Antenna
  • DME indication instrument
37
Q

What does RADAR stand for?

A

Radio detection and ranging

38
Q

Working principle of a RADAR

A

It uses radio waves to determine the bearing and distance of an object. An antenna transmits radio waves which will bounce back when in contact with an object, and return with information.

39
Q

Different kinds of RADAR types

A

Primary RADAR:
Gives direction, distance and speed. No transponder needed.

Secondary RADAR:
Gives additional altitude, identification and information. Transponder needed.

40
Q

Working principle of INS

A

A navigational aid using accelerometers to determine position, orientation and speed, based on dead reckoning principle, without external references. You need a fixed starting point, and the longer you fly, the more inaccurate it gets, so it has to be updated once in a while.

41
Q

What does INS stand for?

A

Inertial Navigation System

42
Q

Working principle of LDNS, and what does it stand for?

A

Light doppler navigatjonal system.

It radiates electromagnetic waves in four directions, which are reflected by the surface.

Uses the doppler effect to determine lateral movement. It works by waves being expanded or compressed, resulting in a change of frequency. There will be a higher frequency in the front, and a lower frequency in the back.

VERY detectable!

43
Q

Working principle of GPS

A

Working with at least 4 satellites, which transmit signals containing name, position and time. When receiving these signals, time can be computed and the position as well.

In aviation we use 8+ satellites for detecting wrongful information and redudancy.

44
Q

What is D-GPS?

A

Differential GPS.

Working with a ground station that can help eliminate time errors and improve accuracy. A special receiver is needed.

IHTC (1 decks)

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