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900 SERIES™ INTRODUCTION
Your 900 Series™ Ultra Wide Screen Fishing System comes in the following
configuration:
• Humminbird® 947c 3D Combo: Ultra Wide Screen Fishing System with
Chartplotter (Maps) and Dual Frequency 455 kHz and 83 kHz Transducer, GPS
Receiver included.
HOW THE 900 SERIES™ WORKS
Sonar uses sound waves to determine the presence and location of underwater
objects. The time measured between the transmission of the sound wave and the
reception of any reflection can be used to determine distance from an object. Analysis
of the reflected signal can also be used to determine location, size, or composition of
underwater objects.
Humminbird® products consist of two main components: the sonar unit and the
transducer. The sonar unit contains the transmitter and receiver, as well as the user
controls and LCD display. The transducer is mounted beneath the water surface and
converts electrical energy from the transmitter into mechanical pulses or sound
waves. The transducer also receives reflected sound waves and converts them back
into electrical signals for display on the sonar unit.
The transmit and receive cycle 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.
A number of variables affect the nature of information which can be derived from the
sonar return. Sonar signals generated at a higher frequency have the advantage of
greatly increased sonar resolution, although the distance (depth) a high-frequency
signal can travel is relatively short. A low frequency signal can travel great distances,
but provides poor sonar resolution. The shape of the transmitted sonar signal greatly
affects the information available as well. A single wide beam has a large area of
coverage but poor resolution of detail. A narrow beam has excellent detail, but only a
limited area of coverage.
3D SONAR
Your 900 Series™ Fishing System uses a six-element transducer
that transmits at 455 kHz and is capable of reaching depths of
240 ft (75 m). Each transmitted beam is 16 degrees in width and
is symmetrical. The six beams are lined up next to each other to
provide a total coverage of 53 degrees from side to side, and 16
degrees from front to back. Using multiple narrow beams
together gives you a wide area of coverage for terrain
interpretation and fish location, without sacrificing the detail
only a narrow beam can provide. Your 900 Series™ Fishing
System gathers information from a continuous series of these
returned signals. It then interprets this information to create a
detailed 3-dimensional view of the terrain passing beneath
your boat as you travel across the water.
2D SONAR
Your 900 Series™ Fishing System also has the capability of
displaying traditional 2-dimensional sonar information from
either a 455 kHz beam or an 83 kHz beam. The 455 kHz single
beam has the advantage of providing increased sonar
resolution but is limited to a depth capability of 240 ft
(75 m). The 83 kHz single beam sonar has the advantage of
providing sonar information to 1000 ft (330 m) but the sonar
resolution is not as great as with the 455 kHz single beam.
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