Humminbird 383c Operation Manual page 52

531450-1_A - 383c_Eng.qxd 11/18/2005
resolution (vertical multiplied by horizontal) is often less important than the "Vertical
Pixel" resolution. See Pixels, Vertical.
Pixels, Vertical: Vertical Pixels are a number of vertical picture elements in a single
column on an LCD display. A greater number of vertical pixels provide finer resolution of
targets detected by sonar. Essentially, a vertical distance (the depth), when divided by a
larger number, breaks that distance into smaller samples, each representing a smaller
area and thus providing more detail. In fishfinders, vertical pixels are more critical than
horizontal pixels because the horizontal axis of the display represents time, or history.
Sonar information on the horizontal axis can vary greatly, depending on boat speed and
the Chart Speed setting. A greater number of horizontal pixels show more sonar history
that the boat has passed through. On many models, Humminbird® provides the most
vertical pixels to provide a better display resolution. See Chart Speed and Pixels.
Power Output: Power output is the amount of sound energy emitted into the water by
the sonar transmitter. Power output is measured using either RMS (Root Mean Square)
or P-T-P (Peak-to-Peak) measurement systems. Either method is acceptable, but it is
important, when comparing power outputs, to make sure that the same measurement
system is being used for both outputs, because P-T-P numbers are 8 times higher than
RMS numbers. Greater power output allows the sonar signal to penetrate through
weeds and thermoclines, reach deeper depths and operate more effectively in noisy
environments, such as when the boat is running at high speed.
Pulse Width (Pulse Length): Pulse Width is the length of time that a sonar sound burst
is transmitted into the water. Shorter pulse widths provide better target separation, but
cannot travel to great depths. Longer pulse widths provide better depth penetration, but
result in poorer target separation. Humminbird® varies pulse width based on depth to
optimize both target separation and depth performance. See Target Separation.
QuadraBeam™: QuadraBeam™ is a Humminbird® sonar configuration that uses four
sonar beams for a more detailed bottom image. QuadraBeam™ uses the DualBeam
PLUS™ configuration for downlooking, and also adds two additional beams to look to
the left and right. The sonar beams pointing to the left and right provide the ability to
spot fish and structure over a wide 90° area, and to identify on which side of the boat
they are located. See DualBeam PLUS™.
Quick Disconnect Mount: The Quick Disconnect Mounting system is an exclusive
Humminbird® feature that permits the unit to be easily removed from the mounting
base by pressing a release button, and re-installed by simply snapping it back into place.
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All cable connections are made when installing, so that no separate wiring connections
are required. Additionally, the mount offers 90° tilt and 360° swivel capability to adjust
the viewing angle of the unit as you move about the boat.
Real Time Sonar: Real Time Sonar is a Humminbird® technology that delivers ultra-fast
sonar transmitter/receiver operation and results in a more detailed instantaneous view
of what is under the boat. The Real Time Sonar window is a vertical band at the right side
of the display that shows the instantaneous sonar return from the transducer at a
particular instant. The RTS® Window menu option permits the user to adjust the
window to show the full sonar signal return, or just a narrower band that indicates
intensity using grayscale. Real Time Sonar relies on very fast Sonar Update Rate (Ping
Speed). See Sonar Update Rate.
Receiver: See Transmitter.
Second Return: The Second Return is a term that describes the appearance of a second
sonar return below the primary sonar return (bottom contour) at exactly twice the true
depth. The second return is caused by the same sonar energy bouncing off the bottom
once, rebounding to the water surface and then traveling back down to the bottom to
be reflected again. Second returns are more common in shallow water and over hard
bottoms; it is actually possible to see a third sonar return under some circumstances.
The second return provides useful information to help determine bottom hardness, as
areas with harder bottoms will generally create a second return. The second return can
be used as a guide to set Sensitivity when in shallower water.
Sensitivity: Sensitivity is a user feature that adjusts the sensitivity of the sonar
system to show more or less detail in the water. Higher sensitivities are often
preferred, however, when the water contains debris (silt, storm debris, etc.) and it
can be difficult to pick out targets. Conversely, if sensitivity is set too low, relevant
targets may be missed.
SONAR: SONAR is the acronym for SOund and NAvigation Ranging. Sonar technology
uses precision sound bursts transmitted underwater to determine the distance and
other attributes of objects in the water. Distance can be determined because the speed
of sound in water is constant, and the time for the signal to return is measured. Sound
also travels very quickly underwater, making sonar a responsive, cost-effective tool.
Sonar is the basic technology behind all recreational and commercial fishfinding and
depthfinding devices.
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