Humminbird 343c User Manual download pdf (Page 4)

How Sonar Works

Sonar technology is based on sound waves. The 300 Series™ Fishing System uses

sonar to locate and define structure, bottom contour and composition, as well as

depth directly below the transducer.

Your 300 Series™ Fishing System sends a sound wave signal and determines distance

by measuring the time between the transmission of the sound wave and when the

sound wave is reflected off of an object; it then uses the reflected signal

to interpret location, size, and composition of an object.

Sonar is very fast. A sound wave can travel from the surface to a depth of 240 ft

(70 m) and back again in less than 1/4 of a second. It is unlikely that your boat can

"outrun" this sonar signal.

SONAR is an acronym for SOund and

NAvigation Ranging. Sonar utilizes precision

sound pulses or "pings" which are emitted

into the water in a teardrop-shaped beam.

The sound pulses "echo" back from objects

in the water such as the bottom, fish and

other submerged objects. The returned

echoes are displayed on the LCD screen.

Each time a new echo is received, the old

echoes are moved across the LCD, creating

a scrolling effect.

When all the echoes are viewed side by

side, an easy to interpret "graph" of the

bottom, fish and structure appears.

The sound pulses are transmitted at various

frequencies depending on the application.

Very high frequencies (455 kHz) are used for

greatest definition but the operating depth

is limited. High frequencies (200 kHz) are

commonly used on consumer sonar and

provide a good balance between depth. Low

frequencies (83 kHz) are typically used to

achieve greater depth capability.

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Humminbird 343c User Manual Page 4