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the apparent sensitivity because the weaker signals appear bolder. Inverse grayscale
works well in very clear water. Debris-laden water often appears as a lot of clutter
on the screen.
Instant Image Update: Instant Image Update is a Humminbird® feature that updates all
the sonar information on the display when Sensitivity and a variety of sonar settings
(Bottom View, Range, etc.) are modified. This differs from the traditional functionality
that only updates the new sonar information collected after the setting change. Instant
Image Update permits more accurate fine-tuning of the display because the user can see
the results on the complete sonar graph. When combined with the Freeze Frame
feature, the user can adjust and understand the effects of many different sonar settings
quickly and easily.
Maximum Depth Menu: The Maximum Depth Menu is a Humminbird® feature that
optimizes performance based on the maximum operational depth set by the user. Many
Humminbird® units can operate across a very broad depth range (up to 2500 feet) which
causes the unit to "look" up to that full depth under some circumstances. Due to the speed
of sound in water, this can result in less responsiveness because the unit has to wait for a
longer period of time to receive the sonar signal. When the Maximum Depth menu is set
to a lower value, the unit only looks up to the setting, which increases the responsiveness
of the unit. This is an important feature for anyone operating in shallower depths!
Noise: Noise is unintentional, external sound waves that interfere with the optimal
operation of sonar. Noise appears as random "dots" on the display, and is caused by a
variety of sources. Electrical noise (from trolling motors, bilge pumps, VHF radios)
typically manifests as a consistent dot pattern. Electrical noise can be isolated by
selectively turning on and off other electrical devices to determine the source. Often re-
routing the power cable, or connecting to an alternative power supply (second battery)
can help overcome electrical noise. Hydrodynamic noise (from propeller and/or hull
cavitation) has a more random appearance and is generally related to boat speed, so
that faster operation results in more noise. Hydrodynamic noise can be overcome by
proper transducer installation. Many Humminbird® products have a Noise Filter menu
setting that allows the user to clear the screen of noise that is difficult to eliminate.
Pixels: Pixels are the "picture elements", or small square blocks, that make up the image
on the LCD. Measured as a vertical by horizontal number (i.e. 640V x 320H), this key
specification typically indicates the quality of resolution. In fishfinders, the total
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. 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.
