23 - Additional UW Systems, Countermeasures, & Non-Acoustic ASW

Question 1

What is a Multistatic/Bistatic SONAR

Answer 1

Requires at least 2 components at different locations
- 1 Active transmitter
- 1+ passive receiver

Ability to use multiple systems

Question 2

What is a Variable Depth SONAR (VDS)?

Answer 2

Adjustable SONAR to receive data from multiple depths
- Active/Passive
- Towed from ship
- Operates above or below sonic layer depth

Self Noise decreases with depth

SQS-62 (DART), SQQ-89 MFTA, MH60R ALFS Dipping SONAR

Question 3

What is a sonobuoy?

3 Types

Answer 3

Small, self contained SONAR system usually deployed by aircraft
- Low (no) self-noise
- Variable depth
- Passes info via VHF radio link

DIFAR
VLAD
DICASS

Question 4

What is DIFAR?

Answer 4

DIrectional
Finding
Acoustic
Receiver
- Horizontally Directional
- Bearing & Doppler
- Can take multiple depth inputs

Passive System

Question 5

What is VLAD?

Answer 5

Vertical
Line
Array
DIFAR
- Vertical linear array
- Vertically directional beam
- Used when NL_amb is high

Passive System

Question 6

What is DICASS

Answer 6

DIrectional
Command
Activated
Sonobuoy
System
- Horizontally Directional
- Range & Bearing
- Adjustable depth setting

Active System

Question 7

What are two ways to deploy sonobuoys?

Answer 7

• MH-60R
• P-3 (Older system)

Question 8

Methods of Non-Acoustic Detection

Answer 8

• Visual
• Infrared (FLIR) Detection
• RADAR
• ESM
• Magnetic Anomaly Detection (MAD)

Question 9

What is a Magnetic Anomaly Detector (MAD)?

Answer 9

• Measures change in Earth’s magnetic field
• Submarine must be reasonably shallow
• Poor open-ocean search capability
• Green target localization and verification

Limited range

Question 10

Types of Underwater Countermeasures

Answer 10

• SLQ-25 NIXIE
• PR.AIR.I.E
• MASKER

Question 11

What is NIXIE?

AN/SLQ-25

Answer 11

Noise Maker
- Surface towed torpedo decoy
- Acoustic signal draws torpedos away from ship

Question 12

What is PR.AIR.I.E?

Answer 12

Propeller Air Induced Emission
Air ejected near propeller masks cavitation-generated noise

Question 13

What is MASKER?

Answer 13

Uses bubbles to create a screen for the ship
- Bubbles reflect hull noise back into ship

Question 14

Torpedo Countermeasures (CM) used by subs and ships

Answer 14

1. ADC CM - generate submarine passive & active noise
2. NAE CM - BB noise maker, raise SNR
3. Decoys - mobile targets