3 Electronic Attack

Question 1

Disruptive EA: How does Noise Jamming work?

Answer 1

We can increase the ambient noise in the receiver bandwidth so that the SNR becomes too low to allow detection.

Question 2

Active vs Passive EA

Answer 2

Active: Emission of energy

Passive: No emission of energy

Question 3

What is Disruptive EA

Answer 3

Increasing ambient noise to blind enemy radar

Question 4

What are two requirements for joise jamming to work?

Answer 4

Directed at the enemy receiver’s antenna
Cover the enemy receiver frequency bandwidth

Question 5

What is Burnthrough Range?

Answer 5

Range where radar echo becomes visible over the Jamming.

Below the Burnthrough Range, the (enemy) radar echo is visible.

After the Burnthrough range, the jamming signal is stronger than the radar return.

Question 6

What are the components of the Jamming Equation?

Answer 6

Signal Strength S
Jammer Strength J (note that it is only one way propagation)

Signal to Jamming Ratio

Question 7

Spot Jamming

Answer 7

Question 8

Barrage Jamming

Answer 8

Question 9

Swept Spot Jamming

Answer 9

Question 10

What is the tradeoff relevant to Jamming?

Answer 10

Power vs. Bandwidth

You need to spread your power accross the bandwidth to be effective over that frequency range.

Question 11

Jamming Tactics: Self-Screening

Answer 11

A single aircraft must both jam and attack. Power must be distributed between the two.

Question 12

Jamming Techniques: Escort

Answer 12

A more specialized aircraft may be used which is equipped specifically for jamming. More power can be used for jamming.

The Jammer is with the group for a balance between Stand-ff and Forward Deployed.

Question 13

Jamming Tactics: Stand-Off

Answer 13

Jammer is behind the attack aircraft to remain safe. But it has less jamming signal strength.

Question 14

Jamming TacticsL Forward Deployed

Answer 14

The Jammer aircraft is forward to increase the jamming power. But the aircraft is more vulnerable.

Question 15

What is Deceptive EA? What are 3 methods?

Answer 15

Multiple Target Generation
Range Deception
Angle Deception

Question 16

What are Repeater Jammers?

Answer 16

Incident signal is repeated and amplified appropriately to create false echo’s IOT change the range perceived by enemy radar.

Question 17

What is a Responsive Repeater Jammer?

Answer 17

Received signal parameters are stored to be used long after the pulse has ceased.

Question 18

What is a False Target Generator?

Answer 18

Creates mutliple images on radar display, difficult to matinain over a number of pusles

Question 19

Range Gate Pull-Off (RGPO) with diagram.

Answer 19

Question 20

Inverse Gain

Answer 20

Sends out jamming pusles in-between incoming pulses, which cause a constant gain at the enemy receiver. This makes it appear as though it is on target.

Question 21

How is Inverse Gain Jamming overcome?

Answer 21

Monopulse.

Question 22

Cross-polarization jamming

Answer 22

The jammer take the incoming pulse, flips the polarization, and sends it back out. The cross-polarized pulses appear as false lobes, making it appear at a different angle.

Downside is it requires a lot of power at the transmitter to appear the same power level at the receiver due to the cross-polarization.

Question 23

Cross-Eye

Answer 23

Sends two signals which are phase shifted IOT create a null in the direction of own self and constructive signal in another angle from the receiver.

Requires two separate antennas

Question 24

What is Passive EA / ECM?

Answer 24

Signature Reduction
Decoys

Question 25

How do we reduce visual signature?

Answer 25

Paint colour

Question 26

How do we reduce infrared signature?

Answer 26

Insulation Light coloured paint Exhaust cooling Pre-wet

Question 27

How do we reduce radar signature reduction

Answer 27

Less corner reflectors Smaller superstructure RAM Obtuse angle design Less deck fittings

Question 28

What are the three ways Decoys are deployed?

Answer 28

Confusion Distraction Seduction

Question 29

Decoys: Confusion

Answer 29

Employed during the search phase. Used to deny accurate bearing and range information

Question 30

Decoys: Destraction

Answer 30

Used when missile is in-flight but not locked on Provides an alternative for the missile to lock-on to.

Question 31

Decoys: Seduction: Dump

Answer 31

(Chaff + Decoy) Aim is to break missile lock Used with RGPO

Question 32

Decoys: Seduction: Centroid

Answer 32

Chaff deployed all around the ship to create a much larger target. By the time the missile intercepts, the ship will have moved away and the missile will track the largest RCS which is the chaff cloud.

Question 33

How does Chaff work?

Answer 33

Resonant Dipoles act as radar reflectors. There are many sizes of ribbon because the greatest re-radiation is when the length is half a wavelength.

Question 34

What is a limitation of Chaff?

Answer 34

Difficult to manufacture with width < 0.2 mm Launching Dispersal Polarization - chaff clouds often devide into two clouds because the horizontally polarized ribbons fall slower than vertivally polarized

Question 35

Name two broad categories of EA

Answer 35

Active and Passive

Question 36

Name two categories of active EA

Answer 36

Disruptive and deceptive

Question 37

What is an objective of jamming?

Answer 37

To conceal your location

Question 38

Name 4 hamming tactics

Answer 38

Self-screening Escort Stand-off Forward deployed

Question 39

Name EA techniques for creating angular errors in searching/tracking radars

Answer 39

Inverse Gain Cross-polarization Cross-eye jamming