3 Comms and EW Flashcards
EM Waves are affected by what 4 behaviours?
Reflection
Refraction
Diffraction
Attenuation
Define Reflection
Angle of incidence = Angle of reflection
Define Refraction
Caused by a change of velocity as an electromagnetic wave passes from one medium to another.
Define Diffraction
Deflection of waves around edges of obstacles placed in their path
Define Attenuation
Reduction (fading) of a signal
What 2 variables vary the amount of diffraction?
Wavelength
Size of the gap
What do we use to refract waves in the atmosphere?
Ionosphere
What do we use to refract waves in the atmosphere?
Ionosphere
What propagation mechanism is used to take advantage of the ionosphere?
Refraction
Describe Doppler
The apparent frequency shift from the point of the observer
What is a surface wave? (Bands?)
Wave that follows the curvature of the Earth’s surface. Used for long distances
VLF, LF, MF to some extent
What is a sky wave? (Bands?)
Wave that refracts off of the layers of the atmosphere (ionosphere). Can be used for very long distances.
HF is predominantly used due to need for refraction.
What is a space wave? (Bands?)
NOT one that goes to space!
Combines LOS and Earth-reflected pathways.
VHF, UHF bands used.
What are the effects of the atmosphere on propagation via refraction? (Pres, Moisture, Temp)
Pressure has no significant impact
Increase in moisture increases refraction
Decrease in Temp increases refraction
Name the 3 different types of refraction
Sub-Refraction (away from surface)
Normal
Super-Refraction (towards to the surface)
What is ducting?
Waves trapped between layers in the atmosphere.
Can be at ground level or at higher altitudes.
What is scatter?
Regions of turbulence containing variations in refractive index, deflect small portions of energy and can be picked up.
What are the 3 primary properties of EM wave energy
Wavelength
Amplitude
Frequency
What are the EM bands (low > high Hz)
Radio Microwaves IR Visible UV X-ray Gamma Ray Cosmic Ray
What orientation are the electric and magnetic fields shown?
Electric - Vertical
Magnetic - Horizontal
….. frequency waves are more susceptible to attenuation.
Higher
Describe the EM bands with frequency ranges
3KHz>VLF<30KHz>LF<300KHz>MF
MF<3MHz>HF<30MHz>VHF<300MHz>UHF
UHF<3GHz>SHF<30GHz>EHF<300GHz
Sky wave is affected mostly by what 2 factors?
Angle of Incidence
Frequency
Define the Maximum Useable Freq of a sky wave
Highest frequency at which refraction can take place at a given angle of incidence.
Space waves use what EM bands?
VHF, UHF
What is the ground wave portion of a sky wave?
Due to the width of the transmission cone, this is the ‘surface wave’ that will occur
What is the dead space portion of the sky wave?
The area past where by the ground wave has weakened significantly. But before where the return from the refraction of the atmosphere can be picked up.
What are the FREQUENICES, Types of Propagation (Surf, Sky, Space), and Uses of HF, VHF, UHF?
HF > 3-30 MHz/ SKY WAVE - single and multiple hops few thousand miles/ reliable continuous wave(CW) and radio transmission (RT)
VHF > 30-300MHz/ SPACE WAVE - within radio horizon/ Marker beacons, ILS Localizer, Radio telephone, Nav aids: VOR, PLB
UHF > 300MHz-3GHz/ SPACE WAVE - within radio horizon/ Radio telephone, ILS glide path, Pulse radio altimeters, TACAN, VORTAC, Search and GCI radars
What is a limitation of HF?
Noise contamination
What is a limitation of VHF/UHF?
Operating range - typically LOS comms.
Power has little impact on extending range
What is a limitation of bandwidth?
Data rate vs capacity.
This has limitations due to the power required to transmit successfully.
What are the 2 types of radio systems?
Guided - Wires/cables
Unguided - Waves through atmosphere
Describe the radio system
Message In – [Transducer] – Baseband Signal –[Modulator and Power Amp]– Aerial
Channel
Aerial–[Demodulator]–Baseband Recovered–[Transducer]–Message Out + Noise
How many frequencies are available and what are their spacing, in VHF and UHF?
VHF - 1300 frequencies at 8.33KHz spacing
UHF - 7000 frequencies at 25KHz spacing
Aircraft comms usually use what freq bands?
UHF - Military aircraft control
VHF - Civil and Military aircraft control
What are the 3 components of the V/UHF radio system?
Adapter Unit
Control Unit
Aerials
What does the ADAPTER unit do in a V/UHF radio system?
Converts data from series to parallel.
Can provide 1KHz tone.
For use in tactical situations where speech is not advisable
What does the CONTROL unit do in a V/UHF radio system?
Selects radio function (Tx+Rx, Tx+Rx+Guard, Tx+Rx+Homing, Tx+Rx+G+H)
Mode selection
Manual Frequency Selection
Why do we typically have 2 UHF aerials?
UHF may attenuate significantly across aircraft
Describe some points of Intercom Discipline
- Mic should be off unless speaking
- Monitor radio before, during and after speaking
- Procedure should be followed
- Crew members should NOT switch off/leave intercom without informing other crew members.
What is the difference between PRIMARY and SECONDARY Radar?
Primary - Operates independently of subject a/c
Secondary - A signal is used to trigger a response from equipment in the subject a/c.
What is the purpose of SECONDARY Radar
- Used to detect and identify an a/c and determine range and bearing.
- Important function in Identification of Friend or Foe (IFF).
- The interrogator may be co-located with search radar or as a standalone system.
What is the name of the piece of equipment in the a/c that an interrogator seeks to interogate?
Transponder
What frequency does an interrogator interrogate at?
1030 MHz
What frequency will a transponder reply at when interrogated?
1090 MHz
A transponder provides automatic communication with who?
Air Traffic Control
How many possible transmit codes are available to a transponder?
4096
What does SSR stand for?
Secondary Surveillance Radar
SSR and … could be referred to as siblings?
IFF
IFF - Mil
SSR - Civvy/Mil
SSR (Secondary Surveillance Radar) can be degraded/ rendered inaccurate due to:
FRUITing - Friendly UnIntentional Transmission
Garbling - Multiple a/c in close proximity (Red Arrows)
Sidelobe Signals - Transponder triggered by radar sidelobes and interrogator beam.
Transponder Suppression - When the transponder is unable to respond due to it taking a very short (125 microsec) break.
How long are the codes that pilots set the transponder to respond with?
4 digits
What are the 3 SSR transponder modes?
A, C, S
Mode S provides a …-way data link?
TWO-way
Each a/c fitted with Mode S is assigned a …… address code
Unique
The Mode S signal, known as ‘Squitter’. Is received by ATC and who?
Other Mode S capable a/c
Mode S transmits information every …. second(s)?
1
Mode S feeds into what larger system?
Airborne Collision Avoidance System (ACAS)
Having unique IDs in Mode S removes what phenomena?
FRUITing and Garbling
What does TCAS stand for?
Traffic Alert and Call Avoidance System
Name the Military IFF modes.
1, 2, 3, 5
Name the Civilian SSR modes
A, C, S
Describe Mode 1
Military mode that comprise the framing pulses and information pulses set on COCKPIT control panel.
Describe Mode 2
Same as Mode 1. Military mode that comprise the framing pulses and information pulses.
However, NOT selectable in flight but preset on the transponder.
Describe Mode 3/A
- Est. and maintain ID of a/c
- Est. position of a/c
- Facilitate hand off between ATS units
- Supplement primary radar
- Detect a/c squawking 7700, 7600, 7500.
Describe Mode C
Provides information on the vertical position of an a/c in flight
What are the 2 levels of Mode S?
Elementary
Enhanced Surveillance
Describe Mode S
Co-operative radar surveillance system employing ground-based interrogators and airborne transponders.
Evolutionary improvement to the existing SSR system in Mode3/A and C.
Describe Mode 5
CLASSIFIED, Mil ONLY, secure IFF system.
Define and describe the 3 key emergency squawk codes
7700 - Emergency situation
7600 - 2-way comms lost with ground
7500 - Unlawful interference i.e. hijacking
Name some examples of Link Units
Ground Stn Reconnaissance a/c or unit Offensive a/c or unit AWACS a/c Capital Ships
What are the 3 types of EW?
Electronic Support Measures (ESM) Electronic Attack (EA) Electronic Protection (EP)
What does ESM stand for?
Electronic Support Measures
What does EA stand for?
Electronic Attack
What does EP stand for?
Electronic Protection
What does RWR stand for?
Radar Warning Receiver
Describe Range Advantage
The ability of you radar to see an object before it sees you
The RWR provides you with…
Range Advantage
Direction Finding
An RWR uses what techniques to determine direction?
Amplitude and Phase comparisons
Within EA we have ECM. What does ECM stand for?
Electronic Counter Measures
ECM is used to _____ the effectiveness of a radar
REDUCE the effectiveness
ECM techniques can fall under 2 categories. These are…
Electronic Jamming
Electronic Deception
Define Electronic Deception
Deliberate radiation, re-radiation, alteration, absorption or reflection of EM energy.
Done to confuse, distract, or seduce an enemy or their systems.
List some means of Electronic Deception
Decoys Chaff Tactics Stealth IR Countermeasures
Electronic Protection (EP) is all about making it as _____ and as _____ as possible for an adversary to have an impact on your operations.
DIFFICULT and as COSTLY as possible
EP is provided by …
- Freq Agility
- SOPs
- Equipment Design
- Parallel Ops
- Planning
To reduce the effectiveness of an incoming threat. Your deception signals need to be accepted by the adversaries missile’s ______.
Receiver
ESM is used to _____, ______ and _____ sources of intentional and ________ radiated EM energy.
ESM is used to INTERCEPT, IDENTIFY and LOCATE sources of intentional and UNINTENTIONAL radiated EM energy.
What factors affect Radar Cross Section?
Shape
Size
Aspect
Build Materials
The aim of the IR jammer is to ….
….disrupt the modulated signal coming from the IR missile so as to cause errors in the missile guidance.
EP involves all actions taken to ______ ______, ______ and ______ from any effects of friendly, or enemy, employment of EW that ______, ______ or ______ friendly combat capability.
EP involves all actions taken to PROTECT PERSONNEL, FACILITIES and EQUIPMENT from any effects of friendly, or enemy, employment of EW that DEGRADE, NEUTRALIZE or DESTROY friendly combat capability.
Reducing RCS seeks to minimise the amount of …..
RADAR ENERGY reflected back towards to radar.
The aim of IR decoys is to …..
present a target to the missile that is more compelling than the a/c.
What does DIRCM stand for?
Directional Infra Red Countermeasures
How does DIRCM work?
- Detects incoming missile with Missile Warning System (MWS).
- IRCM head applies false signal to missile.
- False signal jams missile guidance.
- A/C no longer in missile FOV.
What is the purpose of the ground marshallers?
To ensure a/c are manoeuvred safely on the ground
When marshalled on the ground, who is responsible for the safety of the a/c?
The a/c commander is always responsible for the safety of the a/c
Describe the AFFIRMATIVE signal?
Thumbs Up
Describe the NEGATIVE signal?
Thumbs Down
Describe the STOP signal?
Crossed arms above head
Describe the THIS WAY signal?
Straight arms raised above head
Describe the PROCEED TO NEXT MARSHALLER signal?
Arms pointing/moved towards the direction of the next marshaller.
Describe the CONNECT ELECTRICAL POWER signal?
Two fingers into fist
Describe the DISCONNECT ELECTRICAL POWER signal?
Two fingers out of fist
Describe the START ENGINE signal?
Arms above head.
- Left hand of marshaller Fingers/flashes indicating engine number.
- Right hand of marshaller. Around in circle.
Describe the CUT ENGINE signal?
Chop across neck
Describe the FIRE signal?
Infinity symbol in one hand and pointing towards fire with other
Describe the FLAPS LOWER signal?
Open flat hands apart
Describe the FLAPS RAISE signal?
Close flat hands together
Describe the CHOCKS IN signal?
Bring hands and thumbs (pointing in) together at 6 oclock
Describe the CHOCKS OUT signal?
Move hands and thumbs (pointing out) apart from 6 oclock
Describe the MOVE AHEAD signal?
Both arms straight out in front then brought towards the body
Describe the SLOW DOWN signal?
Hands moved in a downwards direction with palms facing down
Describe the TURN LEFT signal?
Marshaller’s right hand pointing to your left with other moving in direction required.
Describe the TURN RIGHT signal?
Marshaller’s left hand pointing to your right with other moving in direction required.
Describe the BRAKES ON signal?
Closing fists with arms out front
Describe the BRAKES OFF signal?
Opening fists with arms out front
Describe the REQUEST TO MOVE PERSONNEL TOWARDS A/C signal?
One arm pointing towards personnel and other straight in the air
Describe the CLEARANCE TO MOVE PERSONNEL TOWARDS A/C signal?
A/c commander single arm towards face. Palm to face.
“Chop across neck” indicates what signal?
CUT ENGINE
“Thumbs down” indicates what signal?
NEGATIVE
“Crossed arms above head” indicates what signal?
STOP
What are the “actions on” if visual is lost with the ground marshall?
STOP immediately and seek further assistance
Name the 3 types of radiotelephony transmissions
Clearance
Instructions
Information
What time reference should be used unless told otherwise?
UTC
What is the PROWORD for
“True or Accurate”?
CORRECT
What is the PROWORD for
“I wish to know or obtain”?
REQUEST
What is the PROWORD for
“Taxi on active runway in opposite direction to use”?
BACKTRACK
What is the PROWORD for
“What’s the readability of my transmission”?
HOW DO YOU READ
What is the range of the readability scale?
1-5
What is the PROWORD for
“Yes”
AFFIRM
What is the PROWORD for
“No”
NEGATIVE
What is the PROWORD for
“I repeat for clarity or emphasis”
I SAY AGAIN
What is the PROWORD for
“Ignore”
DISREGARD
What is the PROWORD for
“I have finished transmitting and don’t expect a response”
OUT
What is the PROWORD for
“Verify something is correct”
CONFIRM
What is the PROWORD for
“I have received and understood last transmission”
ROGER
What is the PROWORD for
“Let me know you received and understood message”
ACKNOWLEDGE
What is the PROWORD for
“Establish contact with next ATC unit. Your details have been passed”
CONTACT
What is the PROWORD for
“A formal handover has not been arranged, your details have not been passed”
FREECALL
The suffix CONTROL refers to what type of service?
CONTROL - Area Control
The suffix RADAR refers to what type of service?
RADAR - Radar (in general)
The suffix APPROACH refers to what type of service?
APPROACH - Approach Control
The suffix TOWER refers to what type of service?
TOWER - Aerodrome Control
The suffix DEPARTURE refers to what type of service?
DEPARTURE - Approach Control Radar Departure
The suffix GROUND refers to what type of service?
GROUND - Ground Movement Control
The suffix ZONE refers to what type of service?
ZONE - Military Aerodrome Traffic Zone (MATZ) crossing
The suffix TALKDOWN refers to what type of service?
TALKDOWN - Precision Approach Radar
The suffix INFORMATION refers to what type of service?
INFORMATION - Flight Information
The suffix RADIO refers to what type of service?
RADIO - Air/Ground Communication Service
The suffix DELIVERY refers to what type of service?
DELIVERY - Clearance Delivery
List good RT Techniques
- Receiver Vol set to optimum level
- Freq check for interference
- Mic correct distance from mouth
- NORMAL tone
- Steady speech rate
- Constant volume
- PAUSE before and after numbers
- No hesitations or ‘er’s
- No excessive use of courtesies
- Ensure push to talk depressed
- Use standard R/F words and phrases
Emergencies can happen where?
On the ground
In the Air
Without Warning
If an emergency occurs, follow what 3 word rule of thumb?
Aviate, Navigate, Communicate
What frequencies are used for emergencies?
- 5 MHz
243. 0 MHz
Name the 3 standard emergency Mode 3/A squawks
7700 - Emergency
7600 - Total Radio Failure
7500 - Unlawful Interference
What single word does “MAYDAY MAYDAY MAYDAY” indicates?
Distress
What single word does “PANPAN PANPAN PANPAN” indicates?
Urgency
Describe what “MAYDAY MAYDAY MAYDAY” conveys?
Distress - A/c is threatened by serious or imminent danger requiring immediate assistance
Describe what “PANPAN PANPAN PANPAN” conveys?
Urgency - Safety concern for a/c, other vehicle or pax but not requiring immediate assistance
In an emergency transmission you should include what information?
- Callsign
- Type of a/c
- Nature of emergency
- Captain’s intentions and assistance required
- Present or last known position, level and heading
- Pilot quals (if relevant)
- Any other information
“Securite Securite Securite” is used for what purpose?
Inform all air traffic that a message contains info affecting safety
What is the distance between the Tx (Transmitter) and Rx (Receiver) known as?
Skip distance
What do EM waves consist of?
Electric + Magnetic Field
What function on the intercom station box can be set to bypass the press to talk switch?
Hotmic
What part of the crew comms system (CCS) is provided at each of the principal crew stations and permits individuals to select Tx and Rx as required?
Intercom Stn Box
What frequencies does IFF/SSR use?
1030 MHz - Interrogate
1090 MHz - Transponder
Why was Mode S introduced?
Support the automation of Air Traffic systems
Which Mil IFF and Civ SSR modes are the same?
Mil Mode 3
Civ Mode A
Which Mil IFF modes can be set in the cockpit?
Mode 1 + Mode 3
What are the 3 types of EW?
ESM, EA, EP
What is the name for actions taken to intercept, identify and locate intentional and unintentional radiated EM energy?
ESM
What is the name for actions taken to prevent or reduce an enemy’s effective use of the EM spectrum, such as jamming and EM deception?
EA
What equipment is designated to detect, localize and identify threat radars so that appropriate countermeasures can be taken?
RWR - Radar Warning Receiver
What is designed and programmed to identify threats, give warning to the crew and, where available, generate countermeasures?
Defensive Aid Suite (DAS)
List some examples of possible measures that provide Electronic Protection?
- Planning
- Equipment Design
- Frequency Diversity and Agility
- Spread Spectrum