Undersea Warfare Flashcards
A sonar transducer can be compared to what?
Speaker
Signal strength lost as sound waves travel through water is known as what?
Transmission loss
What sea state causes the greatest amount if absorption
Whitecap waves
Sound waves in seawater travel how many times faster than sound waves in the air?
4 times
What sea floor surfaces have the least amount of signal loss?
Smooth and hard
Multiple reflections of a sound wave is referred to by what term?
Reverberating
Meaning of divergence on sound waves
Wave spreads out and becomes weaker with distance
What is the most important factor affecting the speed of a sound wave in seawater?
Temperature
An increase in the salinity of seawater has what effect on the sound wave?
Speed increases
What is the minimum number of sonobuoys normally deployed during a USW mission?
3
Sonobuoys that transmit an acoustic pulse and detect a resulting echo are classified a what type of sonobuoy?
Active
What are the three methods of deploying a sonobuoy?
Pneumatic, free-fall, and cartridge
How are sonobuoys activated?
Saltwater battery activation
What happens to the sonobuoy after the battery dies?
It sinks to the bottom
The acronym SONAR is derived from what words?
Sound navigation and ranging
When the source of a sound wave is moving away from the receiver, what apparent change in the sound wave takes place? (Doppler effect)
The frequency decreases
What are the 3 most common propagation paths for sound waves
Direct
Bottom bounce
Convergence
Sonobuoy descent-retarding devices are necessary for what reason
Reduce water entry shock
A LOLFAR sonobuoy uses what type of hydrophone
Omnidirectional
angles of change in the Earths natural magnetic fielf in the east-west direction is known by what term?
Variation angle
Max range at which a submarince may be detected depends on the intensity of its magnetic anomaly what what other factor?
The sensitivity of the detector
maneuver noises caused to eddy current flow can be minimized by taking what action?
making slow aircraft maneuvers
any magnetic field may be defined in terms of what number of axial coordinates?
3
roll, pitch, yaw
what is the purposed of the submarine anomaly detector (SAD) system?
separates submarine anomalies from magnetic noise.
