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Ground School Revision > Comms and EW > Flashcards

Comms and EW Flashcards

1
Q

What are the three primary qualities of wave energy?

A

Wavelength

Amplitude

Frequency

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2
Q

What is Wavelength?

A

The distance over which the wave’s shape repeats.

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3
Q

What is Amplitude?

A

The vertical size of the wave, measured from the mean level.

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4
Q

What is Frequency?

A

The number of occurrences of a repeating event, measured in cycles per seconds, or Hertz (Hz).

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5
Q

How is wavelength affected by frequency?

A

Increased frequency = shorter wavelength

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6
Q

What is the difference between Primary and Secondary radar?

A

Primary

Operates independently of the aircraft, it depends on receiving a radar echo reflected passively by a target.

Secondary

A transmitted radar signal is used to trigger a response from equipment in the subject.

IFF - Military

SSR (Secondary Surveillance Radar) - Civvie

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7
Q

What are the key principles of IFF/SSR?

A

IFF and SSR are normally operated in conjuction with a primary radar.

A coded interrogation signal is transmitted to the aircraft and transponders in friendly aircraft receive and decode the signal.

A coded reply signal is sent back. The reply signal is decoded and shown on the radar display along with the primary radar response.

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8
Q

What frequency is the interrogator frequency for IFF/SRR?

A

1030 MHz

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9
Q

What frequency is the reply frequency for IFF/SSR?

A

1090 MHz

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10
Q

What is the duration of the pulses for the Interrogator signal on IFF/SSR?

A

The interrogation frequency is transmitted at 1030 MHz.

It consists of a pair of pulses, each pulse lasting a duration of 0.85μs.

The separation of the pulses determines the mode.

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11
Q

What is Mode S?

A

Mode S is a discrete selective interrogation, rather than a general broadcast, that facilitates TCAS for civilian aircraft.

Mode S transponders ignore interrogations not addressed with their unique identity code, reducing channel congestion. At a typical SSR radar installation, ATCRBS, IFF, and mode S interrogations will all be transmitted in an interlaced fashion.

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12
Q

What is ACAS and what does it provide?

A

Airborne Collision Avoidance System (ACAS)

Collision avoidance protection, situational awareness and enhanced safety.

It is a ‘last resort’ collision avoidance system.

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13
Q

What is TCAS?

A

Traffic Alert and Collision Avoidance System (TCAS)

Utilises SSR technology and utilises the transmissions made by aircraft on IFF frequencies. Warns pilots of the presence of other transponder-equipped aircraft, which may present a threat of a mid-air collision.

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14
Q

What is Mode 4 operating mode?

A

Mode 4 is a secret, military only transponder setting valid for 24 hours. It serves as a military only indentification and can be turned on/off.

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15
Q

What is the emergency Transponder Code?

A

7700

(7-7 off to heaven)

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16
Q

What is the transponder code for a loss of 2-way comms?

A

7600

(7-6 in a fix)

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17
Q

What is the transponder code for hijack/terrorism?

A

7500

(7-5 taken alive)

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18
Q

What types of SSR inaccuracies are there?

A

Fruiting

Garbling

Sidelobe signals

Transponder suppression

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19
Q

What is fruiting?

A

Fruiting

When the interrogating station receives replies from transponders replying to other ground stations. This results in false SSR responses being displayed.

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20
Q

What military mode of IFF cannot be set in the cockpit?

A

Mode 2

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21
Q

What is Garbling?

A

Garbling

If a second aircraft is sufficiently close to the first to be interrogated, garbling may occur. Its reply may overlap that of the first aircraft and the resulting pulses will mix together and be impossible to decode accurately.

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22
Q

What are sidelobe signals?

A

Sidelobe signals

Sidelobe signals may occur if the transponder is triggered by the SSR sidelobes as well as by the interrogator beam. This causes spurious replies on the display and, at short ranges can produce large sidelobes on the response, which may create a complete ring around.

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23
Q

What types of Electronic Warfare are there?

A

Electronic Support Measures

Electronic Attack

Electronic Protection

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24
Q

What is Electronic Attack?

A

Using Electronic Measures or directed energy to attack personnel, facilities or equipment with the intent of degrading or destroying combat capability.

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25
Q

What is a key requirement for Electronic Protection?

A

Frequency Agility

Crypto

Modulation changes

Complex PRF

ie. Havequick

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26
Q

What is the Range advantage when referring to the Radar Warning Receiver?

A

An aircraft that is illuminated by an enemy radar is able to intercept the threat radar transmission before the aircraft itself is detected. It receives the full pulse of the Radar via its RWR, whereas the enemy only receives the reflection.

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27
Q

How can a Radar Warning Receiver identify direction of a radar threat?

A

An RWR can utilise amplitude or phase comparison techniques.

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28
Q

Why do chaff packages consist of varying length filaments?

A

Chaff is cut to match the half-wavelength of the victim’s radar frequency. The varying lengths allow response to varying frequencies.

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29
Q

What is the fundamental parameter behind radar stealth techniques?

A

Radar Cross Section (RCS)

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30
Q

What types of electronic defence measures are there?

A

ECM - Electronic Counter-Measures

ESM - Electronic Support Measures

EPM - Electronic Protection Measures

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31
Q

What must an IR jammer do to be effective?

A

An IR jammer must disrupt the modulation pattern produced by the missile seeker head.

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32
Q

What are the principle paths in which a radio wave can travel?

A

Surface Wave

Sky Wave

Space Wave

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33
Q

What are the three main pieces of equipment for an Electronic Support Measure Kit?

A

RWR - Radar Warning Receiver

MWS - Missile Warning Sytem

LWR - Laser Warning Receiver

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34
Q

What methods of Electronic Attack/Countermeasures are there?

A

Chaff

Flares

Decoys

Stealth Measures

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35
Q

How does an RWR identify threats?

A

Receivers and Antennas

Programme Library cross referenced

Threat identfied

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36
Q

What is the time unit reference used for flying?

A

UTC

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37
Q

What is Distress?

A

Serious, imminent danger requiring immediate interference.

MAYDAY MAYDAY MAYDAY

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38
Q

What is Urgency?

A

There is a safety concern fr aircraft, other vehicle or person on board but does not require immediate assistance.

PAN PAN PAN

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39
Q

What information is required for a MAYDAY call?

A

Type + PoB

Nature

Intentions

Position

Level

hEading

TNIPLE

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40
Q

Surface wave propogation is suitable for what uses?

A

Submarine Communication

Systems requiring consistency of signal over long distances

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41
Q

What frequency bands are suitable for surface wave propogation?

A

VLF

LF

MF (to some extent)

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42
Q

Describe the principles behind skywave propogation?

A

Sky waves ascend into the upper atmosphere and encounter the ionosphere.

The electrically charged particles in the ionosphere allow refraction back towards earth

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43
Q

What is the skip distance in sky wave propogation?

A

The skip distance is the distance between the transmitter and the point of reception of the first sky wave.

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44
Q

What is the maximum usable frequency for sky wave propogation?

A

MUF is the highest frequency at which reflection can take place for a given angle of incidence.

If the frequency is increased, a sky wave penetrates more deeply into the ionosphere before return.

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45
Q

What are the applications of space wave?

A

Short-range comms

TV and FM sound broadcasting

Radar

Nav and Approach aids

Satellite Communication

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46
Q

What is attenuation?

A

Attenuation is the reduction of signal strength, also known as fading. It can be caused by obstructions, absorption, interfering waves and the configuration of the transmitter and receiving antenna.

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47
Q

How can diffraction be utilised to aid signal transmission?

A

Diffraction can occur as waves deflect around obstacles placed in their path.

The wave spread into the shadow zone behind the obstacle. This can be used to send radio signals over a mountain range where there is no LoS path available.

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48
Q

What is the role of a transducer in a basic radio system?

A

The transducer creates a baseband signal from an analogue input (comprising a wide spectrum of frequencies)

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49
Q

What is the role of modulation and power amplification in a basic radio system?

A

It is the role of the transmitting equipment to convert the baseband signal into a suitable part of the frequency spectrum for transmission.

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50
Q

What frequency range is utilised for VHF transmissions?

A

30-300 MHz

For comms:

118 - 136.975 MHz

8.33 KHz spacing

1300 VHF frequencies

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51
Q

What is the spacing of VHF frequencies?

A

8.33 kHz

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52
Q

What is the spacing of UHF frequencies?

A

25 kHz

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53
Q

What is the usable frequency range for UHF transmissions?

A

25.0 - 399.95 MHz

with 25 kHz

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54
Q

What is a CCS and what services will it typically provide?

A

Communications Control System (CCS)

These are used in multi-crew aircraft and offer crew members the option to communicate eachother through an intercom.

Intercom and radio facilities for the crew

‘Listen only’ positions

External inputs: ground crew

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55
Q

What is an auxillary jack box?

A

Cabin/ground crew can use the normal intercom by plugging a headset into a convenient ‘jack box’.

This action closes a switch, which provides a path from the 28V DC supply to the relays in the crew amplifier.

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56
Q

What is the difference between: clearance, instructions and information?

A

Clearance: Requires strict compliance.

Instruction: To be followed and carried out where practically possible and safe to do so.

Information: Of benefit and usefulness between Pilot and Ground personnel in interest of safety.

57
Q

What time is used for transmissions?

A

UTC - Coordinated Universal Time

58
Q

What suffix is used to describe an Area Control service?

A

CONTROL

59
Q

What suffix is used to describe a Radar service?

A

RADAR

60
Q

What suffix is used to describe an Approach Control service?

A

APPROACH

61
Q

What suffix is used to describe an Aerodrome Control service?

A

TOWER

62
Q

What suffix is used to describe an Approach Control Radar/Arrival Depature service?

A

DEPARTURE

ARRIVAL

63
Q

What suffix is used to describe a Ground Movement Control service?

A

GROUND

64
Q

What suffix is used to describe a Military Aerodrome Traffic Zone Crossing?

A

ZONE

65
Q

What suffix is used to describe a Precision Approach Radar service?

A

TALKDOWN

66
Q

What suffix is used to describe a Flight Information service?

A

INFORMATION

67
Q

What suffix is used to describe a Air/Ground Communication Service?

A

RADIO

68
Q

What suffix is used to describe a Clearance Delivery service?

A

DELIVERY

69
Q

On the readability scale what does 1 indicate?

A

1 = Unreadable

70
Q

On the readability scale what does 2 indicate?

A

2 = Readable now and then

71
Q

On the readability scale what does 3 indicate?

A

3 = Readable, but with difficulty

72
Q

On the readability scale what does 4 indicate?

A

4 = Readable

73
Q

On the readability scale what does 5 indicate?

A

5 = Perfectly readable

74
Q

What are the emergency radio frequencies?

A

VHF - 121.500 MHz

UHF - 243.000 MHz

75
Q

What does code 7500 indicate?

A

Unlawful interference

76
Q

What does code 7600 indicate?

A

Total Radio Failure

77
Q

What does code 7700 indicate?

A

Emergency

78
Q

Describe the order of the EM Spectrum from Radio Waves

A

Radio

Microwaves

Infrared

Visible Light

Ultra Violet

X Rays

Gamma Rays

79
Q

What are the three primary qualities of wave energy?

A

Wavelength

Amplitude

Frequency

80
Q

What can the propogation of electromagnetic waves be affected by?

A

Reflection

Attenuation

Refraction

Diffraction

81
Q

What effect reduces signal strength and limits range of radar signals due to Obstructions, Absorption (water vapour) and Dust particles?

A

Attenuation

82
Q

What phenomenon causes waves to appear to bend around objects?

A

Diffraction

83
Q

What effect, caused by a change of velocity as an electromagnetic wave passes from one medium to another?

A

Refraction

Change of medium, velocity changes as medium becomes denser on one side..

Angle in and out do not need to be the same

84
Q

What effect takes place when the angle of incidence is equal to the angle of reflection?

A

Reflection

In and out are identical.

85
Q

Which of the three atmospheric variables cannot affect the refraction of EM waves without changes in the other variables?

A

Pressure

(Atmospheric variables are moisture, pressure, temperature)

86
Q

What are the three classifications for refraction?

A

Sub refraction

Normal refraction

Super refraction

87
Q

What are the three principal paths that radio waves may follow above the Earth, between a transmitter and a receiver?

A

Space

Sky

Surface

88
Q

What effect occurs in abnormal climatic conditions, when some radio waves are refracted back to the surface, then reflected, therefore trapping the wave energy and leading to performance anomalies?

A

Ducting

89
Q

What is the frequency range of the VHF band?

A

30 - 300 MHz

90
Q

What is the frequency of the HF band?

A

3 - 30 MHz

91
Q

What is the frequency of the UHF band?

A

300 - 3,000 MHz

92
Q

What do radio waves consist of?

A

Oscillating electric and magnetic fields which are at right angles, or transverse to the direction of propogation.

Electrical - vertical (fingers in a plug socket, hair stands up)

Magnetic - horizontal

93
Q

Will radio waves pass through many opaque bodies?

A

Yes, but will be attenuated in the process.

94
Q

Which path of radio propogation relies on the Earth to bend the wave to follow the curve of the Earth?

A

Surface Wave - utilises diffraction, VLF and LF

95
Q

What path of radio propogation is referred to as Line of Sight?

A

Space Wave

96
Q

Which frequency bands benefit most from surface wave propogation?

A

VLF, LF

Utilised by Submarines.

97
Q

Roughly how many VHF frequencies are there and what is the spacing?

A

8.33 kHz

1300 frequencies

98
Q

Roughly how many UHF frequencies are available and what is the spacing?

A

25 kHz

7000 frequencies

99
Q

What function on the intercom station box can be set bypass the press to talk switch?

A

Hot Mic

100
Q

What part of the CCS is provided at each of the principal crew positions and permits individual selection of transmitters and receivers as required?

A

Intercom Station Box

At a console or on flight deck, to plug into and select frequencies.

101
Q

What is the difference between primary and secondary radar?

A

Primary - operates independently of subject aircraft, passive. Relies on a reflected signal from the target.

Secondary - Active, relies on transponder replying to interrogation.

102
Q

What frequencies does IFF/SSR use?

A

1030 MHz Interrogator

1090 MHz Response

103
Q

Why was Mode S introduced?

A

Automation of ATC functions.

104
Q

What military IFF mode and civilian SSR mode are the same?

A

IFF Mode 3

SSR Mode A

These are the same.

105
Q

Which military IFF modes can be set on the cockpit control panel?

A

1, 3

Mode 1 (squawk code, task specific i.e. 42/43 for tanker)

106
Q

Which military IFF mode is pre-set and therefore not selectable in flight?

A

2

Airframe specific, precedes Mode S, decoded provided Sqn and tail number

107
Q

Which mode may you be asked to squawk to assist ATC in locating you on their display?

A

IDENT

This switches the transponder into permanent transmit for 18 seconds (3 rotatations)

108
Q

What are the three IFF/SSR codes?

A

7600 - Lost comms

7700 - Emergency

7500 - Hijack

109
Q

What IFF phenomena occurs when the interrogating station receives replies from transponders replying to other ground stations?

A

Fruiting

110
Q

What IFF phenomenon occurs when two aircraft are sufficiently close enough to each other that their resulting reply pulses mix together and cannot be decoded accurately?

A

Garbling

111
Q

What term describes the equipment used to pass tactical information between units in a manner that can be understood and absorbed into the units’ systems?

A

DATA LINK

112
Q

What prefix precedes a distress call?

A

MAYDAY, MAYDAY, MAYDAY

113
Q

What prefix precedes an urgency call?

A

PAN, PAN, PAN

114
Q

What is the correct meaning of ‘roger’?

A

Received all of your last transmission

115
Q

What are the emergency frequencies?

A

VHF 121.500

UHF 243.00

116
Q

What is the usual format for transmitting time?

A

UTC

117
Q

What is the purpose of the military broadcast SECURITE, SECURITE, SECURITE?

A

Temporary danger areas and SAR OPS

Lat/Long, Flight Level, Radius. e.g. Mountain Rescue airborne ops.

118
Q

Transmissions on radio should be…

A

Slow and steady

Normal tone

No hesitations

Constant volume

Listen out, and don’t step on people.

119
Q

What conditions are categorised as urgent?

A

Safety concern but not immediate

120
Q

What information could be included in an emergency message that may be useful to the controller?

A

Pilot’s qualifications

121
Q

If you lose sight of the marshaller you should…

A

Stop.

122
Q

What is the purpose of the ground marshaller?

A

Safety

123
Q

Who is ultimately responsible for the safety of the aircraft whilst manoeuvring on the ground?

A

Aircraft Commander

124
Q

What is the recognised marshalling signal for an engine fire?

A

Figure 8 and point at fire.

125
Q

What is the recognised marshalling signal for cutting an engine?

A

Hand across throat

126
Q

What is electronic warfare (EW)?

A

The use of the EM spectrum to attack the enemy.

127
Q

What are the three types of EW?

A

ESM - Electronic Support Measures

EA - Electronic Attack

EP - Electronic Protection

128
Q

What is the name for actions taken to prevent or reduce an enemy’s effective use of EM spectrum, such as jamming?

A

Electronic Attack

129
Q

What equipment is designed to detect, localise, and identify threat radars so that appropriate countermeasures can be taken?

A

RWR

Radar Warning Receiver

130
Q

An RWR should normally be able to intercept a threat radar before the aircraft itself is detected. The margin of this benefit is known as what?

A

Range Advantage

131
Q

To ensure the ECM are effective what must they do?

A

Transmit waveforms that are accepted by the receiver

132
Q

Why would a pilot consider cancelling afterburners and reducing engine power to ‘military range’ during take off in hostile conditions?

A

Reduce IR profile

133
Q

What name is given to the deliberate radiation or re-radiation of EM energy to impair the effectiveness of electronic devices, equipment and systems?

A

Deception

Jamming

134
Q

Which EW systems are classes as Electronic Support Measures (ESM)?

A

RWR

MWS

LWR - Laser Warning

135
Q

What is designed and programmes to identify threats, give warning to the crew and, where available generate countermeasures?

A

DAS

Defensive Aids Suite

136
Q

What does an aircrafts IR jammer try to disrupt?

A

Modulation of the incoming IR energy

137
Q

Give as many examples as possible of measures that provide Electronic Protection?

A

Planning

Training

Design

HAVEQUICK

Crypto

Parallel Ops

138
Q

What does the acronym RCS stand for?

A

Radar Cross Section

139
Q

What are the main factors affecting an aircraft’s RCS?

A

Size

Shape

Material

Ground School Revision (12 decks)

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