Law Enforcement Agencies use Scanning Sonar
More
and more law enforcement agencies and rescue groups are
discovering the benefits of using scanning sonar in their
underwater search operations.
One key advantage of scanning sonar is its ability to
produce a “picture” of the underwater environment
regardless of water visibility.
It can locate submerged objects from drowning victims
to sunken vessels. Using
this sonar dramatically reduces the time divers spend in the
water, which is extremely important in difficult or dangerous
situations. Another
advantage of scanning sonar is its economical cost compared to
side scan systems, which makes it an affordable alternative
for many smaller departments.
The
way scanning sonar operates in water is similar to the way
radar operates in air. The
sonar transducer transmits a sound wave in the form of a fan
shaped beam that sweeps a circle up to 250 feet in diameter. The beam reflects off any object lying on the bottom of a
river, lake, or ocean. The
reflected wave returns to the transducer where it is received
and transmitted to the surface.
Topside, the sonar signal is processed and displayed on
a standard laptop computer.
The
software has a host of features that allow the scan to be
tailored to fit the needs and preferences of the search
operation. The
operator can select the size of the search area and also
decide whether to scan a complete circle or just a portion of
it. A variety of
color schemes in 256 shades are available to display the sonar
images. There is
a choice of step sizes and sweep speeds, and a sizing tool
shows the length and width of the target.
Scanned data files are stored on the PC’s hard drive
along with the boat’s GPS position, time date, and other
pertinent data. Recorded
files can be played back at any time.
Small file sections and screen shots can be copied for
emailing.
JW
Fishers is one of the primary suppliers of sonar to the
agencies charged with public safety.
Two groups that have recently added Fishers SCAN-650 to
their arsenal of underwater search equipment are a rescue
squad in Vermont and a sheriffs department in California. Members of the Vermont rescue squad visited Fishers factory
for a demonstration of the system.
Several targets were scanned including a mannequin and
a handgun. The
mannequin was weighted and dropped to the bottom of a river.
The SCAN-650 clearly displayed each submerged target.
Team members then discussed an occasional need to
search for vehicles which sometimes mysteriously end up in
local lakes and rivers. Seeing
a scanned image of a sunken car convinced the group this would
be the perfect tool for their
underwater search operations.
