Acoustics

Question 1

What is an SSC?

Answer 1

Submersible Ship Coastal

Question 2

What is an SSK?

Answer 2

Submersible Ship Killer

Question 3

What is an SSP?

Answer 3

Submersible Ship AIP

Question 4

What is an SSAN?

Answer 4

Submersible Ship Auxiliary Nuclear

Question 5

What is an SSGN?

Answer 5

Submersible Ship Guided Missile Nuclear

Question 6

Name the examples of Man Made Noise

Answer 6

• Shipping noise
• Seismic surveying
• Drilling
• Active Transmissions (SONAR)

Question 7

What is an SSBN?

Answer 7

Submersible Ship Ballistic Missile Nuclear

Question 8

What is an SSN?

Answer 8

Submersible Ship Nuclear
(Nuclear powered hunter/killer Sub)

Question 9

Name the examples of Natural Noise

Answer 9

• Biological (whales, dolphins, porpoises and snapping shrimp)
• Ice
• Weather (precipitation/ sea state)
• Seismic

Question 10

What are the advantages and disadvantages of Nuclear Power?

Answer 10

Advantages:
- Enhanced speed
- Enhanced range
- Increased endurance

Disadvantages:
- Constant noise source

Question 11

What are the advantages and disadvantages of Diesel power?

Answer 11

Advantages:
- Very quiet on batteries

Disadvantages:
- Must snort to recharge

Question 12

What are the seven propulsion modes?

Answer 12

• Diesel Direct (DD)
• Diesel Reduction (DR)
• Diesel Electric (DE) - the most common DIESEL power train
• Battery Drive (BE)
• Air Independent Propulsion (AIP)
• Turbine Reduction (TR)
• Turbine Electric (TE)

Question 13

What are the 4 reasons to come to periscope depth?

Answer 13

• Battery Charge
• Communications
• Attack Solutions
• Emergency

Question 14

What is the definition of sound?

Answer 14

Periodic variation of pressure, particle displacement or particle velocity in an elastic medium

Question 15

What effect does an increase of 3dB have on volume?

Answer 15

It’s doubles the volume

Question 16

How does velocity change with Temperature?

Answer 16

Velocity increase by 6ft/s for every 1°F increase in temp.

Question 17

How does velocity vary with Pressure?

Answer 17

Velocity increases 1.6ft/s with every 100ft increase in depth.

Question 18

How does velocity change with salinity?

Answer 18

Velocity increases by 4.6ft/s for every 1 part per thousand of salinity.

Question 19

What does ‘HALT’ mean?

Answer 19

High Away Low Towards

Question 20

What are the three layers of the ocean in descending order?

Answer 20

• Mixed Layer
• Permanent Thermocline
• Deep Water

Question 21

What is the definition of ambient noise?

Answer 21

Any noise within the ocean that is not target related.

Question 22

What are the two types of background noise?

Answer 22

• Natural Noise
• Man Made Noise

Question 23

What is a choke point?

Answer 23

Geographical features, above or below the surface of the sea, that restrict the freedom of movement of a submarine.

Question 24

What are the composition of the sea bed in descending order and are each layer a reflector?

Answer 24

• Sand bottom - Yes, they are a good reflector
• Rock Bottom - Yes, but jagged edges can cause acoustic energy to disperse
• Mud and Silt (Ooze) - No

Question 25

What are the 4 things a LOFAR Graph display?

Answer 25

- Time - Frequency - Intensity - Direction

Question 26

What is a Shaft Rate (SR)?

Answer 26

The number of times a propellor shaft rotates in one second.

Question 27

What is a Blade Rate (BR)?

Answer 27

The number of times a blade passes a given point in one second.

Question 28

How many Shafts and Blades do military vessels have?

Answer 28

Up to 4 shafts 4-7 Blades

Question 29

How many blades do Large and Small/Medium merchant vessels have?

Answer 29

Large = 4 - 7 blades Small/Medium = 3 - 4 blades

Question 30

What are the two types of diesel engines?

Answer 30

2 Stroke 4 Stroke

Question 31

What is the Crankshaft Rate (CSR)?

Answer 31

The number of times the crankshaft rotates in one second.

Question 32

What is the Cylinder Firing Rate (CFR)?

Answer 32

The number of times and individual cylinder fires in one second.

Question 33

What is the Engine Firing Rate (EFR)?

Answer 33

The number of times the engine fires in one second.

Question 34

What is the Engine RPM (ERPM)?

Answer 34

The number of times the crankshaft rotates in one minute.

Question 35

Which engine causes a ‘Saw Tooth’ Pattern?

Answer 35

4 stroke engine

Question 36

Name the ocean floor in descending order.

Answer 36

1 - Continental Shelf 2 - Continental Slope / Rise 3 - Deep Ocean Basin (which is divided into: - Abyssal Plain - Deep trenches - Ridges - Seamounts (Pinnacles / Guyots)

Question 37

Name the 6 countries with nuclear powered Subs

Answer 37

- China - France - India - Russia - UK - USA

Question 38

What is a DSRV?

Answer 38

Deep Sea Rescue Vehicle

Question 39

What are the two categories underwater sound detection is split in to?

Answer 39

- Active Sonar - Passive Sonar

Question 40

What is the doppler effect

Answer 40

The apparent change in frequency due to relative motion between a source and a receiver.

Question 41

What is CPA

Answer 41

Point a vessel passed from a high to low frequency.

Question 42

What are the six pieces of info that can be gained from a cpa

Answer 42

1.F0 2.speed 3.Range 4.Bearing 5.Track 6.Depth

Question 43

What is the speed calculation

Answer 43

Spd=(Fmax-Fmin) x C/ F0

Question 44

What is the range equation

Answer 44

Range= speed x time x 17

Question 45

What does DSCPA mean

Answer 45

Doppler shift closest point of approach

Question 46

What does the amount of Doppler Shift Closest Point of Approach (DSCPA) depend on?

Answer 46

● Target Velocity ● Frequency ● Range

Question 47

What are the 3 main requirements of a successful underwater detection system.

Answer 47

Good penetration or sensitivity High resolution High data rate

Question 48

What is an AN/SSQ-36B Bathy Buoy?

Answer 48

(Expendable Bathythermograph) Type: Temperature sensing buoy Life: 12 mins Depth: 2625ft (800m) RF Channels: 1-99 selectable

Question 49

What are the operating depth, operating life and channels for a SSQ-53G DIFAR

Answer 49

Operating depth: 90,200,400,1000ft Operating life:0.5,1,2,4,8 hours Channels: 1-99 (except 57,58,93

Question 50

What is the AN/SSQ-62E DICASS?

Answer 50

(Directional Command Activated Sonobuoy System) - Operating Depth: - D1 (Shallow): 50,150 or 300ft - D2 (Deep): 90, 400 or 1500ft - Operating Life: 60 mins (50 ping secs) - Channels: 1-99, selectable (except 57,58 and 93)