How Your Sonar Works - Eagle Cuda 250i S/Map Installation And Operation Instructions Manual

NOTICE!
The storage and operation temperature range for your unit is from
-4 degrees to +167 degrees Fahrenheit (-20 degrees to +75 degrees
Celsius). Extended storage or operation in temperatures higher or
lower than specified will damage the liquid crystal display in your
unit. This type of damage is not covered by the warranty. For more
information, contact the factory's Customer Service Department;
phone numbers are listed on the last page.

How Your Sonar Works

Sonar has been around since the 1940s, so if you already know how it
works, skip down to read about the relatively new technology of GPS.
But, if you've never owned a sonar fish finder, this segment will tell you
the underwater basics.
Sonar is an abbreviation for SOund NAvigation and Ranging, a technol-
ogy developed during World War II for tracking enemy submarines. A
sonar consists of a transmitter, transducer, receiver and display. In
simple terms, here's how it finds the bottom, or the fish:
The transmitter emits an electrical impulse, which the transducer con-
verts into a sound wave and sends into the water. (The sound frequency
can't be heard by humans or fish.) The sound wave strikes an object
(fish, structure, bottom) and bounces back to the transducer, which
converts the sound back into an electrical signal.
The receiver amplifies this return signal, or echo, and sends it to the
display, where an image of the object appears on the scrolling sonar
chart. The sonar's microprocessor calculates the time lapse between the
transmitted signal and echo return to determine the distance to the
object. The whole process repeats itself several times each second.
Your sonar unit can record a log of the sonar signals that scroll across
the screen and save them in its memory. (These recordings are also
called sonar charts or sonar graphs.)
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