16 - SONAR Intro & SVP

Question 1

Why SONAR?

Answer 1

• Fast speed of propagation (approx. 4.3 times faster than air)
• Tactically significant ranges are possible

Question 2

Detection Range of SONAR

Answer 2

50% POD occurs when S-N = DT

POD (Prob. of Detection)
S-N (Signal-Noise)
DT (Detection Threshold)

Question 3

Two ways to exploit sound

Answer 3

• Active SONAR
• Passive SONAR

Question 4

What is Active SONAR?

Answer 4

Gives Bearing and Range to target
- Actively sends pings out to find targets

Question 5

What is Passive SONAR?

Answer 5

Gives Bearing to target
- Can triangulate position with multiple bearings

Question 6

What is Intensity (I)?

Answer 6

Certain amount of energy per second (power) is crossing a unit area

I α P²

Question 7

What is Sound Pressure Level (SPL)?

Answer 7

Bridges pressure and intensity metrics to better understand

Dimensionless units of decibels (dB)

Question 8

3 Elements to tactically exploit sound energy

Answer 8

• Source
  1. Object that vibrates
• Medium
  1. An elastic medium (air or water)
• Detector / receiver

Temp is the most influential factor in speed of sound in water

v = 1500 m/s (Speed of sound in water)