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of enhancing 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. 640 V x 320 H),
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.
