Humminbird 981 manual Series Introduction, HOW the 900 Series Works, Side Imaging Sonar

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900 SERIES™ INTRODUCTION

Your 900 Series™ Ultra Wide Screen Fishing System comes in several different configurations. See the following list of products, all of which are covered by this manual, to find your 900 Series™ configuration:

NOTE: Only the 987c SI Combo model comes with GPS and built-in cartography.

•Humminbird® 981c SI: Ultra-Wide Screen Fishing System with Side Imaging and Dual Frequency Transducer, optional GPS support

•Humminbird® 987c SI Combo: Ultra-Wide Screen Fishing System with Chartplotter (Maps) and Side Imaging and Dual Frequency Transducer, GPS Receiver included.

HOW THE 900 SERIES™ WORKS

Sonar technology is based on sound waves. The 900 Series™ Fishing System uses sonar to locate and define structure, bottom contour and composition, as well as depth directly below the transducer. Your 900 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 ¼ of a second. It is unlikely that your boat can "outrun" this sonar signal.

SIDE IMAGING SONAR

Your 900 Series™ 987c SI Combo and 981c SI use Side Imaging sonar to provide a wide yet precise survey of a large area of water, including detailed bottom topography and fish-attracting structure orientation. The Side Imaging transducer returns are processed into an image similar to an aerial photograph. Typically, the Side Imaging sonar searches an area that is 240 feet wide, with a depth limitation of 100 feet. See What’s on the Side Imaging Display and Understanding Side Imaging for more information.

DUALBEAM PLUS™ SONAR

Your 900 Series™ is shipped with a 200/50 kHz DualBeam PLUS™ sonar system with a wide (74°) area of coverage. DualBeam PLUS™ sonar returns can be blended together, viewed separately or compared side-by-side. DualBeam PLUS™ is ideal for a wide range of conditions - from shallow to very deep water in both fresh and salt water. Depth capability is affected by such factors as boat speed, wave action, bottom hardness, water conditions and transducer installation.

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