How Sonar Works, 3D Sonar, 2D Sonar | Humminbird 47, 531338-1

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How Sonar 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 Matrix™ 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 Matrix™ 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 Matrix™ 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.

NOTE: Depth capability is affected by such factors as boat speed, wave action, bottom hardness, water conditions and transducer installation.