Sensors 12

Question 1

EPM (Electronic Protective Measures) definition?

Answer 1

Actions taken to ensure friendly effective use of the EM spectrum despite the enemy’s use of electromagnetic energy.

• Active EPM: Detectable measures
• Passive EPM: Undetectable measures

Question 2

They are 2 ways of Electronic Protective measures. What are they?

Answer 2

Indirect and Direct Threat RADAR

Question 3

Indirect Threat RADAR are used to provide the detection and identity of airborne targets. Give 4 techniques to combat this type of jamming

Answer 3

1. High Power: Defeat noise jamming by significantly increasing BTR (burn thru range)
2. SLC (Side Lobe Cancellation): Counters side lobe jamming; uses 2 antennas (omni & main)
3. Variable Polarization: To maximize the signal to noise ratio and thus minimize the effects of jamming.
4. Instantaneous Automatic Gain Control: Helps prevent RADAR Rx saturation in the presence of noise jamming or heavy ground clutter; Reducing gain too far can hide valid targets.

Question 4

Once the target has moved into range of direct threat RADAR, it uses different types of EA techniques to cover the attack, so Direct Threat RADAR must use different types of EP to counter that!..which ones (5)?

Answer 4

1. Variable Pulse Repetition (introduce false target)
   i. Staggered PRF
   ii. Jittered PRF
2. Scan on Receive Only (inverse gain jamming)
   i. Lobe On Receive Only (LORO)
   ii. Conical Scan Receive Only (COSRO)
   iii. Track-While-Scan Receive Only (TWSRO)
3. Moving Target Indicator (MTI) (separate moving target from background clutter: Coherent & Non-Coherent systems
4. Frequent Agility: move from one frequency to another
5. Pulse compression (Initially Tx a coded, long duration, high-energy pulse.)

Question 5

Communication EPM must me able to defend against the 5 D’s

Answer 5

1. Deception
2. Detection
3. Demodulation
4. Direction Finding (by triangulation)
5. Disruption (jamming)

Question 6

What are the 3 approaches to protecting communication systems?

Answer 6

1. Confinement of signals
2. Masking of signals
3. Encryption of signals

Question 7

Although EO systems are considered mostly passive sensors, there are ways to counter the EA during an attack. what are the 3 ways?

Answer 7

1. FLIR EPM (Forward looking IR)
   a. Dual Seeker Frequency bands
   b. Millimetre wave band (high cost)
2. IR Missiles (Switches)
   a. Rise-time or Temporal
   b. Kinematic
   c. Dual-Colour or Spectral
   d. Spatial
3. IR Missiles (Responses)
   a. Simple Memory
   b. Seeker Push - Ahead
   c. Seeker Push – Pull
   d. Sector Attenuation

Question 8

EP refers to an overall Air Defense System charac. that gives the system greater resistance to an enemy use of EA. The most common types of System EP include what? (5)

Answer 8

1. Frequency Diversity
2. Passive Detection
3. Home-On-Jam
4. Sensor Fusion
5. The Operator