USING THE 250DX
HOW SONAR WORKS
HOW SONAR WORKS
Your Humminbird 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 Humminbird 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 Humminbird 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' (70m) and back again in less than ¹⁄₄ of a second. It is unlikely that your boat can "outrun" this sonar signal.
The 250DX 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 capability 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 combination of a large area of coverage and a high level of detail.
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