ADP crystals are piezoelectric, a property required in some active sonar transducers ( the alternative being transducers that use magnetostriction ).
42.
When active sonar is used to measure the distance from the transducer to the bottom, it is known as echo sounding.
43.
The Navy admits the Bahamas stranding was likely caused by mid-range sonar but contends the low-frequency active sonar wouldn't harm whales.
44.
An active sonar system was probably installed by the end of 1940, but it is uncertain when it was actually done.
45.
Conventional active sonar may be more effective than towed arrays, but the small size of modern littoral submarines makes them difficult threats.
46.
However, there have been protests about the use of medium and low frequency high-powered active sonar because of its effects on whales.
47.
Once the torpedo's passive sonar has detected something, it will switch over to an active sonar and will begin to track the target.
48.
No matter whether active sonar or passive sonar, the information included in the reflected signal can not be used without technical signal processing.
49.
Ballistic missile submarines are designed to conceal themselves while on patrol, and the use of active sonar would immediately reveal the boat's position.
50.
When active sonar is used by surface ships or submarines, it is typically activated very briefly at intermittent periods to minimize the risk of detection.
