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Module 1 Basic > Equipment > Flashcards

Equipment Flashcards

1
Q

What are the 3 functions of ATC equipment?

A

Surveillance, communication and navigation

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2
Q

What is attenuation?

A

Reduction of amplitude

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3
Q

Properties of electric waves

A
  • Able to transfer energy
  • Medium is required for propagation
  • The longer the distance, the smaller the affect
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4
Q

Properties of radio waves

A
  • Electromagnetic waves able to transfer energy
  • Medium not required for propagation
  • Spread out in space
  • The longer the distance, the smaller the effect and will eventually fade away
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5
Q

What are the main characteristics of a radio wave? (6)

A

Frequency - The number of cycles per second/revolutions per second expressed in Hertz (Hz)

Period - The time for a wave to complete 1 sinus cycle expressed in seconds (s)

Amplitude - Maximum positive or negative magnitude of a wave expressed in pressure difference (sound wave), volt or amp (electrical wave) or volt per metre (radio wave)

Phase - The current state of a wave in degrees through its 360° cycle

Wavelength - The distance a wave propagates over 1 complete cycle in metres (m)

Speed - Speed of light if in a vacuum (3 x 10^8m/s)

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6
Q

What is the main application of HF radio for aviation?

A

Long range voice and data communication

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7
Q

What are the main applications for VHF radio in aviation?

A

Navaids (VOR, ILS localiser and markers) and civil/military VHF COM

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8
Q

What are the main applications for UHF radio in aviation?

A

Navaids (ILS glide path and DME), GPS, primary/secondary radar and military UHF COM

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9
Q

What is the frequency range for ILS localiser and VOR’s?

A

108-118MHz
VOR - even numbered tenth only (from 108-112MHz)

108-112MHz - ILS Localiser - odd numbered tenth only

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10
Q

What is the frequency range for ILS glide path?

A

329-335MHz

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11
Q

What are the frequency ranges for COMs?

A

118-137MHz (VHF band - Civil)

138MHz-144MHz, 230-329MHz and 335-400MHz (VHF/UHF band - Military)

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12
Q

What are the emergency frequencies?

A
  • 121.5MHz (Civil)
  • 243MHz (Military)
  • 406.025 MHz (Emergency locator transmitter)
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13
Q

Define modulation and its main purposes

A

Process of varying one or more properties of a carrier signal, with a modulating signal that typically contains information to be transmitted.

Purpose:

  • Transposition of audio signals to frequencies more favourable for transmission
  • Multiple use of transmission path
  • Generation of favourable signal to noise (S/N) ratios.
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14
Q

What are the 3 types of modulation and which is most dominant in civil aviation?

A

Amplitude, frequency and phase modulation. Amplitude modulation is most dominant in civil aviation.

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15
Q

What does a high modulation factor do?

A
  • Increases S/N ratio and therefore penetration of RT signal.
  • Modulation factors >100% cause cross channel interference and distortion.
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16
Q

What are the 3 properties of amplitude modulated carrier?

A
  • Constant frequency.
  • Depth of modulation represents Audio Frequency (AF) amplitude.
  • Carrier envelop represents twice AF frequency.
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17
Q

What are the 3 types of amplitude modulation?

A

A1 - Simplest form. Keying the RF carrier signal on and off to transmit digital information for example morse code.

A2 - AF with constant amplitude modulates RF carrier by varying its amplitude.

A3 - AF modulates RF carrier by varying its amplitude proportionally to the AF amplitude.

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18
Q

What is the bandwidth of an A3 carrier?

A

6kHz

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19
Q

What are the 3 properties of frequency modulated carrier?

A
  • Constant amplitude.
  • Frequency deviation represents AF amplitude.
  • Rhythm of frequency deviations represents AF frequency.
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20
Q

What is the doppler effect and how can it be utilised in aviation?

A

Change in frequency of waves emitted by a source moving relative to the observer. Can be utilised in DVOR and primary radar.

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21
Q

What are the 4 propagation mechanisms?

A

Absorption - Attenuation of radio signals depending on material, distance and frequency.

Reflection - When radio waves are reflected at the surface by materials with a higher density and electric conductivity. Can cause double path reception.

Refraction - Change in direction of radio waves passing from one medium to another caused by its change in speed. Effect decreases with increasing frequency.

Diffraction - Bending and spreading of radio waves passing a gap or an obstruction. Effect decreases with increasing frequency.

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22
Q

What is NDB coastal refraction?

A

When a low frequency ground wave from an NDB crosses a shoreline and goes out to sea, it will bend towards the coast due to refraction.

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23
Q

Radio wave propagation characteristics for LF/MF bands (30kHz-3MHz)

A
  • Ground wave propagation
  • Range 600NM
  • High power
  • AM Modulation
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24
Q

Radio wave propagation characteristics for HF band (3-30MHz)

A
  • Sky wave propagation
  • Range 10000NM (Due to reflection in ionosphere)
  • Medium power
  • AM SSB/FM Modulation
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25
Q

Radio wave propagation characteristics for VHF/UHF bands 30MHz-300MHz/300MHz-3GHz and above

A
  • Line of sight propagation
  • Range 200-300 NM
  • low power
  • AM/FM modulation
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26
Q

What are the basic types of antenna used in ATC?

A

λ/2 dipole, λ/4 dipole/monopole, loop, slot.

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27
Q

For a vertically polarised λ/2 dipole antenna, what do reflections through the ground create?

A

Feathers

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28
Q

For a horizontally polarised λ/2 dipole antenna, what do reflections through the ground create?

A

Lobes which can be utilised for a glide path

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29
Q

What is the normal approach angle for glide path?

A

3°

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30
Q

Give an example of an application of a slot antenna in an ACFT.

A

Weather radar

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31
Q

What are the functions/processes of a transmitter (3)

A

Frequency generation, modulation and power generation

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32
Q

What are the functions/processes of a receiver (4)

A

Selection of frequency, RF amplification, demodulation and AF amplification

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33
Q

What does automatic gain control allow?

A

Allows the same volume of audio regardless of how far away the aircraft is.

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34
Q

What does a squelch circuit do?

A

Mutes noise when there is no speech traffic. If received signal is above the adjustable amplitude THR, the loudspeaker is turned on.

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35
Q

What does ATC radio communication redundancy normally consist of?

A

Duplication of elements such as coverage, system/system components, power supplies and transmission paths.

36
Q

What is the standard VHF channel spacing and bandwidth below FL195 at the moment?

A

25kHz and 7.2kHz (Due to temperature and ageing equipment)

37
Q

What new channel spacing standard will be fully implemented by the end of 2018 in Europe and why is this advantageous?

A

8.33kHz and its advantageous as there 3 times as many channels available

38
Q

How is radio horizon calculated?

A

R(NM)=1.23 x Square root of (ACFTS height in feet)

39
Q

Why are additional VHF transmitters/receivers needed in larger areas?

A

Due to range limitations its not possible to cover large areas from 1 location. In areas where range overlaps, interferences will occur such as echo effects, signal fading and opposite phase which may cause cancellation.

40
Q

What is the VHF Climax offset carrier technique?

A

Allows the transmission of the same signal from 2 transmitters in the same area. Frequency of both transmitters is shifted a few kHz (+/-2.5, 4, 5 or 7.5kHz) with respect to the original channel frequency.

41
Q

What are the 6 main types of ACFT communication systems?

A

VHF, HF, SATCOM, SELCAL, ACARS and CPDLC

42
Q

What is SATCOM

A

Satellite communication (worldwide range)

43
Q

What is SELCAL?

A

Selective Calling - Signalling method which can alert individual ACFT that a ground station wishes to communicate with it using either HF or VHF. Receipt in flight deck activates flight deck call system which may light up or produce an audible chime.

44
Q

What is CPDLC?

A

Controller Pilot Data Link Communication - Application which allows direct exchange of text based message between controller and pilot. Resolves ACARS Channel saturation.

45
Q

What is ACARS?

A

ACFT Communications Addressing and Reporting System - used for short message between ACFT and ground via HF, VHF or Satellite radio

46
Q

What is direction finding?

A

Azimuth determination of a radio source. It is used by controllers to find the direction of an ACFT relative to a ground station.

47
Q

What are the advantages (6) and disadvantages (3) of ground based direction finding?

A

Advantages:

  • The ACFT doesn’t require special equipment.
  • Use of 2 or more ground stations allows a position fix to be determined.
  • Controller may select QDM/QDR or QUJ/QTE.
  • Can be used to home an ACFT to a station.
  • Can be of vital importance on emergency frequencies to assist lost ACFT or ACFT whose NAVAIDS have become unserviceable.
  • Can be used to perform a non precision approach.

Disadvantages:

  • ACFT rely on presence of a ground station.
  • If only 1 ground station in range, info is limited to a single bearing at a time.
  • Strictly limited number of ACFT that can be handled by 1 ground station at once.
48
Q

What is the accuracy of DF information and what are the limitations of the system.

A

High accuracy +/- 1°
Limitations are when ACFT is close to overhead the station due to the cone of silence or due to reflections from nearby obstacles.

49
Q

What is RNAV?

A

A method of area navigation which permits ACFT to operate on any desired flight path within the coverage of station referenced navaids or within the limits of the capability of self contained aids or a combination of these.

50
Q

What three components does Performance Based Navigation (PBN) comprise of?

A

Navigation Application, Navigation Specification and Navigation Infrastructure.

51
Q

What is the main difference between RNAV and RNP specifications?

A

On board performance monitoring and alerting is required for RNP.

52
Q

What is the RNAV 5 specification?

A

Track keeping accuracy of +/-5NM for at least 95% of flight time.

Mainly used for en-route applications.

53
Q

What is the RNAV 1 specification?

A

Track keeping accuracy of +/-1NM for at least 95% of flight time.

Used for SIDs and STARs.

54
Q

What is the RNP 0.3 specification?

A

Track keeping accuracy of +/-0.3NM for at least 95% of flight time including on board performance monitoring and alerting function.

Envisaged for all phases of flight.

55
Q

What is an ADF?

A

Automatic Direction Finder - Determines and displays bearing to an NDB.

Frequency range os 190-1750 kHz but can be limited in different countries

56
Q

What are the limitations of an NDB and allowed accuracy tolerance?

A

NDBs suffer from a number of propagation and interference effect that can limit the accuracy of the bearing information (ADF) provided to the pilot.

  • Night effect
  • Mountain effect
  • Coastal refraction
  • Interference
  • Cone of ambiguity

Allowed accuracy tolerance is +/- 6.9°

57
Q

Compare VOR with DVOR (9)

A

Information carrier:
carrier frequencies in the band 108-112MHz (even numbered tenths) and 112-118MHz (even and odd tenths) with a channel spacing of 50kHz

Reference Signal:
VOR - 30Hz FM, DVOR - 30Hz AM

Rotating Signal:
VOR - 30Hz AM, DVOR - 30Hz FM

Rotation frequency:
VOR/DVOR - 30 revolutions per second (30Hz)

Rotation direction:
VOR - clockwise, DVOR - anti-clockwise

Definition:
Rotating and reference signal (each 30 Hz) are in phase when the rotating signal passes through magnetic north.

Azimuth angle:
Phase difference between rotating and reference signals (each 30Hz)

Identification:
Letter transmitted in morse code

Speech signal range (may be VOLMET or ATIS):
300-3000Hz

58
Q

What are the basic principles of a VOR

A

A VOR emits radial bearings (360 which can be selected) which can be used by pilots to fly to or from a VOR station. It has a range of around 130nm.

59
Q

What are the limitations for a VOR and allowed accuracy tolerance?

A
  • SPAMIC
  • Siting errors
  • Propagation errors
  • Airborne equipment errors
  • Monitoring errors
  • Interference errors
  • Cone of ambiguity

Allowed accuracy tolerance is +/- 5.2°

60
Q

Approximately what angle is the cone of silence over a VOR and what are the visible indications that an ACFT is passing through it?

A

+/- 30°

To/from flag in the cockpit will start to flip back and forth

61
Q

What is TACAN?

A

TACtical Air Navigation is a NATO standard military short range navigation and approach aid in the UHF band around 1000Mhz. It has a range of around 200 NM. Provides bearing and range information to military. Civil traffic are able to access DME part only.

62
Q

What is VORTAC?

A

TACAN colocated with a VOR. Both civil and military can access bearing and range information.

63
Q

What is DME?

A

Distance measuring equipment. Provides slant range and complements bearing information (if colocated with a VOR: VOR/DME is an ICAO standard short range navaid)

Range of 200NM

DME frequency range is 962-1213MHz (UHF band)

Tuned with a VOR ghost frequency if no colocated VOR

64
Q

What are is the error tolerance of a DME?

A

0.5NM or 3% of the total distance measured, whichever is greater.

65
Q

What are the advantages and disadvantages of DME?

A

Advantage:
Very accurate + allows for precise position estimation in conjunction with VOR and therefore very useful to ATC for procedural separation of ACFT.

Disadvantages:

  • Slant range only
  • Relatively short range
  • ACFT relies on GND stations
66
Q

What is an ILS?

A
  • Instrument Landing System
  • Ground based radio guidance system which transmits 2 direction beams - the localiser and the glide path.
  • The pilot then receives indications in the cockpit as to to whether the ACFT needs to fly up, down left or right to keep on the correct approach path.
  • Usual descent path is 3 °
67
Q

What is the basic operating principle of the localiser?

A
  • Transmits 2 narrow intersecting beams, 1 slightly to the left of the RWY centre line (90Hz modulation) and one slightly to the right (150Hz modulation). Where they intersect define the ON LOC indication.
  • Airborne receiver determines the separate modulation factors which are depend on the azimuth and displays the difference in depth of modulation (DDM)
  • DDM = M(150) - M(90)
  • Localiser course results from compliance with DDM=0
  • Pilot receives indications on whether they need to fly left of right to keep on the correct path.
68
Q

Why does the LOC need a clearance antenna?

A

To mitigate the effect of side lobes which can be dangerous.

69
Q

What do the terms ILS critical area and sensitive area mean?

A

Critical area:
Area surrounding ILS antenna with dimensions where persons, vehicles (including ACFT) are excluded during ILS operation.

Sensitive area:
Extends beyond the critical area with dimensions where presence of large objects and parked or moving vehicles could cause unacceptable interference to the ILS signal. (Dimensions vary depending on CAT I or CAT II/III conditions)

70
Q

What is the basic operating principle of a glide path?

A
  • Transmits 2 narrow intersecting beams, 1 slightly above required vertical profile (90Hz modulation) and one slightly below (150Hz modulation). Where they intersect define the ON GP indication.
  • Airborne receive determines DDM.
  • DDM = M(150) - M(90)
  • Glide path course results from compliance with DDM=0
  • Pilot receives indications on whether they need to fly up or down to keep on the correct path.
71
Q

Why does the glide path have a hyperbolic shape?

A

Because the glide path transmitter is positioned 180m to the side of the RWY so as not to present an obstacle. Because of the conical radiation characteristic in the approach direction, the glide path can only operate with the localiser.

72
Q

What is the minimum required range of the glide path?

A

10NM

73
Q

Why is the false glide path (6°) dangerous?

A

Glidepath is inverted due to reflection which could cause ACFT using autopilot to pitch nose up when it intersects the 9° glide path which may result in loss of control.

74
Q

What is the advantage/disadvantage of ILS?

A

Advantage - very accurate, guidance down to the surface of the RWY is possible depending on quality of equipment.

Disadvantage - May be affected by atmospheric conditions, interference with FM radio broadcasts or from reflections on objects and buildings.

75
Q

What are the 3 ILS operational performance categories?

A

CAT I:

  • Basic operational category for an ILS system.
  • All IFR equipped and IFR certified pilots allowed.
  • DH not lower than 200ft
  • Either visibility not less than 800m orRVR not less than 550m

CAT II:

  • DH lower the 200ft but not lower than 100ft.
  • RVR less than 300m

CAT III (sub divided into IIIA, IIIB and IIIC):
CAT IIIA:
- DH lower than 100ft but not less than 50ft
- RVR not less than 200m

CATIIIB:

  • DH lower than 50ft or no DH
  • RVR less than 200m but not less than 50m

CATIIC:
- No DH or RVR limitations

NOTE: CAT II and CAT III procedures can only be performed provided:

  • The ACFT is suitably certified.
  • The crew is qualified.
  • ILS system is certified and maintained accordingly.
76
Q

What is NAVSTAR GPS?

A

Navigation System with Timing And Ranging GPS:

  • Intended to work everywhere on Earth at anytime under all weather conditions.
  • Providing extremely accurate position, speed and time measurements.
77
Q

What is the basic working principle of GNSS?

A
  • GNSS receiver calculates its position based on range measurements from the GNSS satellites.
  • Synchronisation of satellite and receiver clocks is essential. This can be achieved with a 4th satellite. Therefore at least 4 satellites are required to calculate a position.
78
Q

What are the sources of error for GNSS? (3)

A
  • Satellite position error - shifts in orbit due to gravitational forces.
  • Satellite clock position - Remaining inaccuracy of time still leads to position error.
  • Ionospheric effects - Most significant source of error. Errors sum up to approx 60m and varies over time and depend son solar activity.
79
Q

What is RAIM?

A

Receiver Autonomous Integrity Monitoring:

  • Determines validity of position solution. With 4 or more satellites, conflicts can be detected by coincidence.
  • With 6 or more satellites any faulty satellite is identified and excluded from the positioning.
80
Q

What is the purpose of GNSS augmentation and what are the 3 types used?

A

To provide the integrity required for the operation as GNSS alone has no integrity guarantee.

ABAS - ACFT based augmentation system:

  • Integrates INS, barometric altimeter and every other navigation sensor.
  • Uses RAIM
  • Availability is lower than GBAS and SBAS as extra satellite required.

GBAS - Ground based augmentation system
SBAS - Satellite based augmentation system

81
Q

What is the primary function of the FMS?

A

Navigation by integration of all other navigation systems - To compute ACFTs position as accurately as possible.

82
Q

What are the shortcomings of existing SSR systems?

A

Due to increasing radio frequency pollution and inherent limitations:

  • Garbling - Interference due to overlapping replies from 2 or more transponders.
  • False Replies Unsynchronised In Time (FRUIT) - Interference at 1 interrogator due to transponder reply from another interrogator.
  • No reply - caused by over interrogation and shadowing
  • Side lobes
  • Reflections and multi path transmission
  • Availability of only 4096 squawk codes.
  • Only average azimuth resolution.
83
Q

What are the main advantages of Monopulse SSR?

A
  • Much better target azimuth measurements.

- Single pulse is sufficient for azimuth measurement.

84
Q

What is Mode S?

A
  • Mode Selective
  • A development designed to supersede existing Mode A and C limitations.
  • Selective interrogation to eliminate garbling and reduce FRUIT.
  • Long term elimination of Mode A squawk code shortages (Each ACFT will have a unique identifier)
  • Coding of altitude in 25ft increments.
85
Q

What is the Mode S uplink frequency and what is it used for?

A

1030MHz

Used for All call or roll call (selective) interrogations

86
Q

What is the Mode S downlink frequency and what is it used for?

A

1090MHz

Used for all call or roll call replies

87
Q

What types of information can Mode S display to a controller?

A
  • Flight ident (24 bits)
  • ACFT position and past position
  • Speed vector
  • Ground speed
  • Flight level
  • Selected altitude
  • IAS
  • Vertical rate
  • Magnetic heading/

Module 1 Basic (12 decks)

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