ISR Fdn 25-2 > Electronic Warfare > Flashcards

Electronic Warfare Flashcards

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1
Q

Define EW.

A

Military action that exploits EM energy to provide SA and create effects.

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2
Q

What are the 3 major sub-divisions of EW ?

A

Electronic attack
Electronic defence
Electronic support

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3
Q

EW Measures are the methods used to achieve EA, ED, & ES. What are the subdivisions for each action?

A

ES - Electronic Support Measures (ESM)

EA - Electronic Counter Measures (ECM)

ED - Electronic Protective Measures (EPM)

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4
Q

Define EA.

A

Use of EM or DE to attack with the intent of degrading, neutralising or destroying.

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5
Q

Name the primary actions undertaken as part of electronic counter measures.

A

Jamming
Deception
Neutralisation

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6
Q

Define jamming.

A

The deliberate radiation, re-radiation or reflection of EM energy to impair effectiveness of electronic devises.

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7
Q

Define deception.

A

The deliberate radiation, re-radiation, alteration or reflection of EM energy to confuse, distract or seduce an enemy

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8
Q

Define ED.

A

Use of EM energy to provide protection to friendly forces and to enable effective friendly use of the EM spectrum.

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8
Q

Define neutralisation.

A

The deliberate use of EM energy to damage enemy devices that rely exclusively on the EM spectrum.

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9
Q

Name the primary actions undertaken as part of electronic protective measures.

A

Passive
Active
EMCON
Electronic Masking

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10
Q

What is passive EPM?

A

Operator training

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11
Q

What is active EPM?

A

Frequency hopping
Burst transmission
Changing the polarization of radar pulse

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12
Q

What is electronic masking?

A

Controls EM radiation on friendly frequencies, to protect the emission characteristics of communications and electronic systems against an enemy’s ES e.g. encryption

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12
Q

What is EMCON?

A

Emissions Control - Controlled use of EM emitters to optimise C2 capabilities whilst minimising detection by an enemy

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13
Q

Define ES.

A

Monitoring the use of EM energy, either actively or passively to provide instant SA and support.

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14
Q

Name the primary actions undertaken as part of electronic support measures.

A

SIGINT - internal - actual content
ESM - external - threat warning

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15
Q

What is SIGINT?

A

Intelligence gathered from both (or either) ELINT and COMINT.

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16
Q

What are the types of threat warning ESM?

A

RWR - radar warning receiver
MWS - missile warning system
LWR - laser warning receiver

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17
Q

What are the military applications of the following frequencies?

ELF
VLF
HF
V/UHF
SHF/EHF

A

ELF – Nav and Comms (Submarine Comms)
VLF – Nav and Comms (Satellite Comms)
HF – Comms and Radars
V/UHF – Comms and Radars
SHF/EHF – Radars

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18
Q

What are the elements of the EM spectrum that comprise EO?

A

Infra-red – missile guidance, imaging lasers
Visible – Lasers, Electro Optics and optics
Ultra-violet – Flare rejection and missile detection

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19
Q

Using the NATO standard frequency code, how does an A frequency differ to an M frequency?

A

A is the lowest freq and M is the highest freq.

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20
Q

Complete the gaps in this diagram.

A
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21
Q

What is the symbol and speed of light?

A

C
162,000 NM/sec
3x10^8 m/s

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22
Q

What is the frequency of a wave with a wavelength of 10cm?

A

3 GHz

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23
What is the frequency of a wave with a wavelength of 3cm?
10 GHz
24
What is a radar cross section?
A measure of how detectable an object is using a radar.
25
What factors affect a RCS?
a. Size b. Shape c. Aspect d. Material e. LBEACS - Lumps, Bumps, Angles, Edges, Cavities and Seams.
26
What is the word RADAR an acronym for?
‘Radio Detection And Ranging'
27
What is a primary radar?
A radar that transmits energy and receives some of that energy back again after it has been reflected by the target.
28
What does a pulse radar measure and how?
Range is measured by pulse/time technique. Bearing is measured by indication of the aerial’s azimuth during its scanning movement.
29
What is the relationship between wavelength and frequency?
As frequency increases, wavelength decreases. They are inversely proportional.
30
How does the frequency of a radar effect it's physical characteristcs?
The lower the frequency, the bigger the radar.
31
What is the equation for wavelength?
λ (cm) = C / f *f = must be x10^ format.
32
What is the to-the-power of format for MHz?
1 x 10^6
33
What is the to-the-power of format for GHz?
1 x 10^9
34
What is the wavelength for a frequency of 3 GHz?
3x10^8 / 3x10^9 = 0.1 or 1x10^-1 = 10 cm
35
What is the wavelength for a frequency of 10 GHz?
3x10^8 / 10x10^9 = 3x10^-2 or 0.03 = 3x10^-2 = 3cm
36
What is a radar mile?
The time taken for a pule to travel to a target distance of one mile and return
37
What is a radar mile for 1NM?
12.36 µs
38
What is the equation for target range?
Target range (NM) = 162,000 x return time / 2
39
Given a return time of 100 µ secs, what is the target range?
40
What is a PPI?
Plan Position Indicator
41
What is a pulse width?
The time duration of a single pulse of energy.
42
What is the equation for pulse length?
Pulse width x speed of light = pulse length(m)
43
Given a pulse width of 1µs, what is the pulse length?
300m
44
Given a pulse width of 0.1µs, what is the pulse length?
30m
45
Given a pulse width of 10µs, what is the pulse length?
3km
46
How is the minimum detection range calculated?
MDR (m) = Pulse Length / 2
47
What will occur if more than one contact is under the range resolution?
They will be seen as one on the PPI.
48
How is range resolution calculated?
Range resolution (m) = Pulse Length / 2
49
What is the definition of PRF?
Pulse repetition frequency - Number of pulses transmitted in 1 second measured in Hz
50
What is the definition of PRI?
Pulse repetition interval - the time between the start of one pulse and the start of the next measured in µs.
51
What is the maximum unambiguous range?
The longest range to which a transmitted pulse can travel out and back before the next pulse is transmitted.
52
How is the MUR calculated?
MUR = ½ Speed of Light / PRF
53
What is the MUR of a radar using a PRF of 2500Hz?
81,000nm / 2500Hz = 32.4nm
54
How is radar horizon calculated?
RH (nm) = 1.23 x √ Æ Height(ft)
55
What is the radar horizon for an antenna that is 5000' high?
1.23 x √ Æ Height(ft) = 87 nm
56
What is the relevance of the aerial rotation period to radar operation?
Must be at such a rate as to receive all responses out to a certain range before moving on. This is linked to the PRF.
56
What are the 3 primary types of radar scan?
Circular Sector Raster
57
What is noise jamming?
Random noise is generated to provide clutter masking the true range and bearing. At a point, the power of the jamming signal is overcome by the strength of the Jammer’s reflection and the Jammers true position will ‘Burn Through’.
58
What is frequency agility?
Rapid changing of frequency to avoid jamming.
59
What is deception jamming?
Mirror the received radar signal and apply multiple time manipulating techniques
60
What is chaff?
Fine strips of metal, made into bundles, cut into different lengths to match the wavelength of the radar
61
What are the chaff response factors?
Length Bandwidth Material Orientation Amount
62
What are decoys?
Prevents Acquisition radars from tracking the airborne platform through Deceptive or Noise Jamming. E.g. BriteCloud
63
What are defences 3 main uses of the EM spectrum?
Radio RADAR EO
64
How does a radar work?
Detecting and locating a contact by means of reflected radar energy.
65
List 4 elements used to describe pulse radar system.
frequency, pulse width, PRF/PRI, aerial rotation period
66
List 1 advantage and 2 disadvantages of decreasing a frequency of a radar system.
longer range / larger antenna, worse target discrimination
67
If a radar has a pulse width of 1μs, how long is the pulse length?
PL = PW x C PL = 1x10^-6 x 3x10^8 PL= 300m
68
Define a radar mile.
The time taken for a pulse to travel one mile and return.
69
Explain why minimum detection range exists.
The closest range at which a radar will see a return due to the rx being blanked while the tx is firing. Determined by PW/PL.
70
What is the name of a radar display?
PPI - plan position indication
71
What is the range resolution with a radar operating a pulse length of 1,200m?
RR = PL / 2 RR = 1,200 / 2 RR = 600m
72
Calculate the maximum unambiguous range of a radar with a PRF of 1,000Hz.
MUR = 0.5xC / PRF MUR = 0.5x162,000 / 1,000 MUR = 81,000 / 1,000 MUR = 81 NM
73
Name 4 missile engagement techniques.
Command guidance Beam riding Homing Track via Missile
74
What is the missile engagement process?
Search Acquire Track Launch Intercept
75
What is the equation for the radar horizon? Calculate it for an antennae height of 15,000ft.
RH = 1.23 x √Antenna height RH = 1.23 x √15,000 RH = 150.6NM
76
What are the 3 types of MWS in current use?
Radar IR UV (Laser)
77
What are the 4 elements to a radar signal?
Frequency PRF/PRI PW/PL ARP
78
How is directional arrival found?
Utilising adjacent antennae
79
What are the 3 functions of an ESM system?
Intercept, Identify, locate
80
What are the 3 types of homing radar and where is the energy source emitted from for each?
Passive - emitted from the target Semi active - emitted from launch platform Active - emitted from missile
81
What are the 3 types of radar scan?
Circular, sector, raster
82
What are the main factors that affect chaff?
Length Bandwidth Material Orientation Amount
83
What factors effect a radar cross section?
Size Shape Material Aspect Lumps. bumps, seams, edges, cavities, angles
84
Name five different types of anti-aircraft weaponary.
Small arms Combined AAA & SAM Land SAM ManPADs Naval AA Air to Air
85
What are the 4 elements of the missile guidance loop?
Sensor Error Guidance computer Steering command
86
What is the brevity code used when a friendly enters a MEZ?
TRESSPASS
87
Other than visual, state 5 aids for finding a target.
EO/IR Chart IFF ESM Voice
88
A radar has the following parameters. What does each parameter indicate about the radar? Frequency: 9.4GHz PRF: 1000 Hz PW: 0.5 m ARF: 2 sec
Frequency (aerial size) PRF (data rate & MUR) PW (tgt discrimination) ARP (matches PRF & MUR)
89
What's the primary use of a TRD?
Towed Radar Decoy
90
Difference between SEAD and DEAD?
Suppression of enemy air defences - soft kill Destruction of enemy air defences - hard kill
91
What frequencies does link 16 operate on and what does it avoid?
969-1206MHz Avoids 1030 and 1090 by 20 MHz either side to avoid interference with IFF.
92
What are the filters used for Link 16 based on?
Affiliation, domain, range
93
What is the J-series message code for Air?
J2.2
94
What is the J-series message code for surface?
J2.3
94
What is the J-series message code for Air Track?
J3.2
95
What is the J-series message code for Surface Maritime?
J3.3
96
What is the J-series message code for Threat Warning?
J15.0
97
What 3 factors can direction of arrival be calculate from?
Amplitude Time Phase
98
What are the characteristics of a command guided missile?
Not fire and forget Overt system Susceptible to counter measures
99
What are the two types of command guidance for missiles?
Command to line of site (CLOS) Command off line of site (COLOS)
100
What is the purpose of aircraft radar homing?
To position the a/c so that the crew can visually ID an unidentified (Non-Squawking or AIS) surface contact.
101
What is mode 2 IFF?
Platform ident
102
What is mode 1 IFF?
Platform function
103
What channel is used for maritime surface comms?
Channel 16 (156.8)
104
What is the ASLA brevity word for Link 16?
TIMBER
105
What does JTIDS stand for?
Joint Tactical Information Distribution
106
What information should be provided in a contact report?
Which What Where Wither Time Track number
ISR Fdn 25-2
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