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Comms and EW Flashcards

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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
What is a key requirement for **Electronic Protection**?
Frequency Agility Crypto Modulation changes Complex PRF ie. Havequick
26
What is the **Range advantage** when referring to the Radar Warning Receiver?
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.
27
How can a Radar Warning Receiver identify direction of a radar threat?
An RWR can utilise amplitude or phase comparison techniques.
28
Why do chaff packages consist of varying length filaments?
Chaff is cut to match the half-wavelength of the victim's radar frequency. The varying lengths allow response to varying frequencies.
29
What is the fundamental parameter behind radar stealth techniques?
**Radar Cross Section (RCS)**
30
What types of **electronic defence measures** are there?
**ECM** - Electronic Counter-Measures **ESM** - Electronic Support Measures **EPM** - Electronic Protection Measures
31
What must an IR jammer do to be effective?
An IR jammer must disrupt the modulation pattern produced by the missile seeker head.
32
What are the principle paths in which a radio wave can travel?
**Surface Wave** **Sky Wave** **Space Wave**
33
What are the three main pieces of equipment for an Electronic Support Measure Kit?
**RWR -** Radar Warning Receiver **MWS -** Missile Warning Sytem **LWR -** Laser Warning Receiver
34
What methods of Electronic Attack/Countermeasures are there?
Chaff Flares Decoys Stealth Measures
35
How does an RWR identify threats?
Receivers and Antennas Programme Library cross referenced Threat identfied
36
What is the time unit reference used for flying?
UTC
37
What is **Distress**?
Serious, imminent danger requiring immediate interference. MAYDAY MAYDAY MAYDAY
38
What is **Urgency**?
There is a safety concern fr aircraft, other vehicle or person on board but does not require immediate assistance. PAN PAN PAN
39
What information is required for a MAYDAY call?
**T**ype + PoB **N**ature **I**ntentions **P**osition **L**evel h**E**ading **TNIPLE**
40
**Surface wave** propogation is suitable for what uses?
Submarine Communication Systems requiring consistency of signal over long distances
41
What frequency bands are suitable for surface wave propogation?
VLF LF MF (to some extent)
42
Describe the principles behind **skywave propogation**?
Sky waves ascend into the upper atmosphere and encounter the ionosphere. The electrically charged particles in the ionosphere allow refraction back towards earth
43
What is the **skip distance** in sky wave propogation?
The **skip distance** is the distance between the transmitter and the point of reception of the first sky wave.
44
What is the **maximum usable frequency** for sky wave propogation?
**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.
45
What are the applications of **space wave**?
Short-range comms TV and FM sound broadcasting Radar Nav and Approach aids Satellite Communication
46
What is **attenuation**?
**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.
47
How can **diffraction** be utilised to aid signal transmission?
**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.
48
What is the role of a transducer in a basic radio system?
The **transducer** creates a baseband signal from an analogue input (comprising a wide spectrum of frequencies)
49
What is the role of **modulation and power amplification** in a basic radio system?
It is the role of the transmitting equipment to convert the baseband signal into a suitable part of the frequency spectrum for transmission.
50
What frequency range is utilised for VHF transmissions?
30-300 MHz For comms: **118 - 136.975 MHz** 8.33 KHz spacing 1300 VHF frequencies
51
What is the spacing of VHF frequencies?
**8.33 kHz**
52
What is the spacing of UHF frequencies?
**25 kHz**
53
What is the usable frequency range for UHF transmissions?
**25.0 - 399.95 MHz** with 25 kHz
54
What is a **CCS** and what services will it typically provide?
**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
55
What is an **auxillary jack box**?
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.
56
What is the difference between: **clearance, instructions** and **information**?
**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
What time is used for transmissions?
UTC - Coordinated Universal Time
58
What suffix is used to describe an **Area Control** service?
**CONTROL**
59
What suffix is used to describe a **Radar service**?
**RADAR**
60
What suffix is used to describe an **Approach Control service**?
**APPROACH**
61
What suffix is used to describe an **Aerodrome Control service?**
**TOWER**
62
What suffix is used to describe an **Approach Control Radar/Arrival Depature service**?
**DEPARTURE** **ARRIVAL**
63
What suffix is used to describe a **Ground Movement Control service**?
**GROUND**
64
What suffix is used to describe a **Military Aerodrome Traffic Zone Crossing**?
**ZONE**
65
What suffix is used to describe a **Precision Approach Radar service**?
**TALKDOWN**
66
What suffix is used to describe a **Flight Information** service?
**INFORMATION**
67
What suffix is used to describe a **Air/Ground Communication Service**?
**RADIO**
68
What suffix is used to describe a **Clearance Delivery service**?
**DELIVERY**
69
On the readability scale what does **1** indicate?
1 = Unreadable
70
On the readability scale what does 2 indicate?
2 = Readable now and then
71
On the readability scale what does 3 indicate?
3 = Readable, but with difficulty
72
On the readability scale what does 4 indicate?
4 = Readable
73
On the readability scale what does 5 indicate?
5 = Perfectly readable
74
What are the emergency radio frequencies?
VHF - 121.500 MHz UHF - 243.000 MHz
75
What does code **7500** indicate?
Unlawful interference
76
What does code **7600** indicate?
Total Radio Failure
77
What does code **7700** indicate?
Emergency
78
Describe the order of the EM Spectrum from Radio Waves
Radio Microwaves Infrared Visible Light Ultra Violet X Rays Gamma Rays
79
What are the three primary qualities of wave energy?
Wavelength Amplitude Frequency
80
What can the propogation of electromagnetic waves be affected by?
Reflection Attenuation Refraction Diffraction
81
What effect reduces signal strength and limits range of radar signals due to Obstructions, Absorption (water vapour) and Dust particles?
Attenuation
82
What phenomenon causes waves to appear to bend around objects?
Diffraction
83
What effect, caused by a change of velocity as an electromagnetic wave passes from one medium to another?
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
What effect takes place when the angle of incidence is equal to the angle of reflection?
**Reflection** In and out are identical.
85
Which of the three atmospheric variables cannot affect the refraction of EM waves without changes in the other variables?
Pressure (Atmospheric variables are moisture, pressure, temperature)
86
What are the three classifications for refraction?
Sub refraction Normal refraction Super refraction
87
What are the three principal paths that radio waves may follow above the Earth, between a transmitter and a receiver?
Space Sky Surface
88
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?
Ducting
89
What is the frequency range of the VHF band?
30 - 300 MHz
90
What is the frequency of the HF band?
3 - 30 MHz
91
What is the frequency of the UHF band?
300 - 3,000 MHz
92
What do radio waves consist of?
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
Will radio waves pass through many opaque bodies?
Yes, but will be attenuated in the process.
94
Which path of radio propogation relies on the Earth to bend the wave to follow the curve of the Earth?
Surface Wave - utilises diffraction, VLF and LF
95
What path of radio propogation is referred to as Line of Sight?
Space Wave
96
Which frequency bands benefit most from surface wave propogation?
VLF, LF Utilised by Submarines.
97
Roughly how many VHF frequencies are there and what is the spacing?
8.33 kHz 1300 frequencies
98
Roughly how many UHF frequencies are available and what is the spacing?
25 kHz 7000 frequencies
99
What function on the intercom station box can be set bypass the press to talk switch?
Hot Mic
100
What part of the CCS is provided at each of the principal crew positions and permits individual selection of transmitters and receivers as required?
Intercom Station Box At a console or on flight deck, to plug into and select frequencies.
101
What is the difference between primary and secondary radar?
**Primary** - operates independently of subject aircraft, passive. Relies on a reflected signal from the target. **Secondary** - Active, relies on transponder replying to interrogation.
102
What frequencies does IFF/SSR use?
1030 MHz Interrogator 1090 MHz Response
103
Why was Mode S introduced?
Automation of ATC functions.
104
What military IFF mode and civilian SSR mode are the same?
IFF Mode 3 SSR Mode A These are the same.
105
Which military IFF modes can be set on the cockpit control panel?
1, 3 Mode 1 (squawk code, task specific i.e. 42/43 for tanker)
106
Which military IFF mode is pre-set and therefore not selectable in flight?
2 Airframe specific, precedes Mode S, decoded provided Sqn and tail number
107
Which mode may you be asked to squawk to assist ATC in locating you on their display?
IDENT This switches the transponder into permanent transmit for 18 seconds (3 rotatations)
108
What are the three IFF/SSR codes?
7600 - Lost comms 7700 - Emergency 7500 - Hijack
109
What IFF phenomena occurs when the interrogating station receives replies from transponders replying to other ground stations?
Fruiting
110
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?
Garbling
111
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?
DATA LINK
112
What prefix precedes a distress call?
MAYDAY, MAYDAY, MAYDAY
113
What prefix precedes an urgency call?
PAN, PAN, PAN
114
What is the correct meaning of 'roger'?
Received all of your last transmission
115
What are the emergency frequencies?
VHF 121.500 UHF 243.00
116
What is the usual format for transmitting time?
UTC
117
What is the purpose of the military broadcast SECURITE, SECURITE, SECURITE?
Temporary danger areas and SAR OPS Lat/Long, Flight Level, Radius. e.g. Mountain Rescue airborne ops.
118
Transmissions on radio should be...
Slow and steady Normal tone No hesitations Constant volume Listen out, and don't step on people.
119
What conditions are categorised as urgent?
Safety concern but not immediate
120
What information could be included in an emergency message that may be useful to the controller?
Pilot's qualifications
121
If you lose sight of the marshaller you should...
Stop.
122
What is the purpose of the ground marshaller?
Safety
123
Who is ultimately responsible for the safety of the aircraft whilst manoeuvring on the ground?
Aircraft Commander
124
What is the recognised marshalling signal for an engine fire?
Figure 8 and point at fire.
125
What is the recognised marshalling signal for cutting an engine?
Hand across throat
126
What is electronic warfare (EW)?
The use of the EM spectrum to attack the enemy.
127
What are the three types of EW?
ESM - Electronic Support Measures EA - Electronic Attack EP - Electronic Protection
128
What is the name for actions taken to prevent or reduce an enemy's effective use of EM spectrum, such as jamming?
Electronic Attack
129
What equipment is designed to detect, localise, and identify threat radars so that appropriate countermeasures can be taken?
RWR Radar Warning Receiver
130
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?
Range Advantage
131
To ensure the ECM are effective what must they do?
Transmit waveforms that are accepted by the receiver
132
Why would a pilot consider cancelling afterburners and reducing engine power to 'military range' during take off in hostile conditions?
Reduce IR profile
133
What name is given to the deliberate radiation or re-radiation of EM energy to impair the effectiveness of electronic devices, equipment and systems?
Deception Jamming
134
Which EW systems are classes as Electronic Support Measures (ESM)?
RWR MWS LWR - Laser Warning
135
What is designed and programmes to identify threats, give warning to the crew and, where available generate countermeasures?
**DAS** Defensive Aids Suite
136
What does an aircrafts IR jammer try to disrupt?
Modulation of the incoming IR energy
137
Give as many examples as possible of measures that provide Electronic Protection?
Planning Training Design HAVEQUICK Crypto Parallel Ops
138
What does the acronym RCS stand for?
Radar Cross Section
139
What are the main factors affecting an aircraft's RCS?
Size Shape Material

Ground School Revision (12 decks)

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