sonar & undersea warfare

Question 1

undersea warfare defensive

Answer 1

stealth

Question 2

undersea warfare offensive

Answer 2

employ acoustic sensors and weapons

Question 3

speed of sound (ocean)

Answer 3

speed of sound varies from point to point in the ocean

Question 4

factors affecting speed

Answer 4

temperature (T), pressure (P), Salinity

Question 5

speed of sound increases with

Answer 5

warmer water, higher pressure, higher salinity

Question 6

shadow zone

Answer 6

region beyond where sound rays travel and sound intensity is negligible

Question 7

surface layer

Answer 7

daily weather, time of day. 150 meters

Question 8

seasonal thermocline

Answer 8

seasons about 1000m

Question 9

permanent thermocline

Answer 9

slightly seasons about 1000m

Question 10

deep isothermal layer

Answer 10

pressure 1000m+

Question 11

deep sound channel (DSC)

Answer 11

axis of minimum sound speed within deep sound channel. 1000m+

Question 12

expendable bathythermograph (XBT)

Answer 12

measures water temp, probe sinks at a known rate, produces a sound velocity profile of immediate area

Question 13

direct propagation path

Answer 13

simplest propagation path. sound ray travels in approx straight linepath between the source and the receiver

Question 14

surface duct

Answer 14

sound waves trapped in the surface layer, surface layer is deep enough to trap sound waves

Question 15

bottom bounce (BB)

Answer 15

sound beam is directed at an angle toward the bottom, the sound beam reflects back toward the surface, path is dependent on the depth, and absorption of sound by the ocean bottom

Question 16

convergence zone

Answer 16

occurs in deep isothermal layer, if depth is great enough, sound rays bend back toward surface

Question 17

self noise

Answer 17

machinery noise, flow noise, cavitation

Question 18

sonar

Answer 18

sound navigation and ranging, consists of source, medium and receiver

Question 19

active sonar system

Answer 19

transducer emits a ping, short burst of energy transmitted thru the water. range is measured, time interval between transmission and return. closely resembles the operation of radar system

Question 20

passive sonar system

Answer 20

ONLY listens, thru hydrophones. displays frequency and bearing, range calculated thru target motion analysis

Question 21

light airborne multi-purpose system (LAMPS)

Answer 21

consists of helicpoter & assets utilized for antisub warfare. dipping sonar, sonobuoys, forward looking infrared (FLIR), magnetic anomaly detector (MAD)

Question 22

sonobuoys

Answer 22

expendable piece of equip. detect underwater sounds and transmit the data back to the search vessel

Question 23

towed array sonar system

Answer 23

multi function towed array (MFTA), PASSIVE sonar receiver, long 3 inch diameter array towed behind surface ships

Question 24

fathometer

Answer 24

acousit system that determines water depth

Question 25

WQC-2 (Gertrude)

Answer 25

two-way voice communications

Question 26

WQC-6

Answer 26

one way coded pulse, sent thru surface ships sonar dome to subs