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USING THE PRO CRAFT UNIT
HOW SONAR WORKS
HOW SONAR WORKS
Your Pro Craft unit uses sonar to
locate and define underwater objects,
define the bottom terrain, as well as
determine distance.
Sonar technology is based on sound
waves. Your Pro Craft unit sends out
a sound wave signal. With this signal
it determines distance by measuring
the time between the transmission of
the sound wave and when the sound
wave is reflected off an object. Your
Pro Craft uses the reflected signal to
interpret location, size and composi-
tion of an object.
Sonar is very fast. A sound wave can travel from the surface to a depth of
240' (70m) and back again in less than 1/10 of a second. It is unlikely that
your boat can "outrun" this sonar signal.
The Pro Craft unit is a dual frequency, dual beam unit, and generates two
distinct sonar signals - one narrow, one wide. Each signal is optimized for
a particular purpose. First, the center beam transmits at a frequency of 200
kHz in a 20 degree (narrow) symmetrical pattern for greater depth capa-
bility and excellent detail. Information from this center beam is used to
draw the graphic representation of the bottom on the display.
Second, the wide beam transmits at a frequency of 83 kHz in a 53 degree
(wide) symmetrical pattern for greater area of coverage. Information from
the wide beam is used to accurately detect the presence and location of
fish. A wide beam has a large area of coverage but limited resolution of
detail. A narrow beam has excellent detail, but within a limited area
of coverage.
The combination of the two beams and dual frequencies provides the com-
bination of a large area of coverage and a high level of detail.
