Lowrance electronic X105C DF, X100C manual How Sonar Works

	Actual capability depends on transducer
	configuration and installation, bottom com-
	position and water conditions. All sonar
	units typically read deeper in fresh water
	than in salt water.
Depth display:	Continuous display .
Audible alarms:	Deep/shallow/fish/zone.
Automatic ranging:	Yes, with instant screen updates.
Auto bottom track:	Yes.
Zoom bottom track:	Yes.
Split-screen zoom:	Yes.
Surface water temp:	Yes.
Speed/distance log:	Optional (requires optional speed sensor).

NOTICE!

The storage temperature range for your unit is from -4 degrees to +167 degrees Fahrenheit (-20 degrees to +75 degrees Celsius). Extended stor- age in temperatures higher or lower than specified will damage the liq- uid 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 Sonar Works

Sonar has been around since the 1940s, so if you already know how it works, skip ahead to the next segment on the typographical conventions used in this manual. But, if you've never owned a sonar fish finder, this segment will tell you the under water basics.

Sonar is an abbreviation for SOund NAvigation and Ranging, a technol- ogy developed during World War II for tracking enemy submarines. (Lowrance developed the world's first transistorized sportfishing sonar in 1957.) A sonar consists of a transmitter, transducer, receiver and dis- play. 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.

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