All submarines and other ocean-going vessels such as frigates and warships
use sonar to navigate through the water. Sonar, which stands for sound navigation
and ranging, maps the features of an environment by transmitting sound waves
and measuring them as they're reflected back.
The pulse transmission of sound waves is used to detect and track targets,
ocean features and other subs and surface ships in the area.
Sonar technicians, also called naval electronic technicians, are trained
to repair, maintain and operate sophisticated acoustic detection equipment
on modern ships and submarines. A sonar operator reads the display screens
or listens to sounds made by other underwater vessels.
Two types of sonar detection are used. Active sonar is used in non-combat
situations -- the sonar operator sends out signals for detecting others in
the area. Passive sonar only listens to sounds emitted from other underwater
vessels, such as propeller noises, for defensive and offensive missions.
In most cases, sonar technicians and operators work in the navy. They first
become trained sailors before receiving additional education in the electronics
Because ships and submarines travel 24 hours a day, sonar technicians must
be available at all hours. They work irregular hours and perform watch-keeping
duties. "When we're at sea, there are always people awake," says Brad Browne.
He is a sonar technician. "We take shifts, but the days are a lot longer."
They may work at sea, in the harbor or on land.
While at work, sonar technicians must be able to withstand cramped living
quarters. They must work above and below the waterline.