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or very shallow water, it is suggested that the user manually selects a fixed depth range.
ZOOM
– The ZOOM button allows you to select the upper range of the portion of the water
column you would like to zoom in on. The actual size of the Zoom window can be adjusted in the
Main Menu. The Zoom feature allows you to focus the display on a specific depth within the
water column and can be a great benefit in a variety of fishing situations. See the separate
ZOOM section below for more info on the ZOOM. Whenever you are utilizing the ZOOM menu,
keep in mind that it “times-out” after 6 seconds.
IR (INTERFERENCE REJECTION)
– The Interference Rejection system is designed to
suppress competing return signals from other sonar units being used within proximity. When
other sonar units are causing interference to the display of the Digital Sonar, activate the IR
feature by depressing the IR button located on the control panel of the Digital Sonar. Interfer-
ence is indicated by unusual signals flashing or scrolling across your display.
There are 12 levels, or channels, of interference rejection. Press the IR button once to open the
IR window, now use the UP/DOWN buttons to select the desired level of IR. The correct level of
IR will be achieved when the display is clear of display clutter. In some extreme cases, clutter
will be greatly reduced but not eliminated.
Anytime two or more sonars are being operated in proximity to each other, there is the potential
for interference. Deep water and hard bottom will increase the likelihood that one or more of the
competing sonars will experience interference. Besides experimenting with different levels of IR,
the anglers experiencing interference can also try having their transducers set at different levels,
going to narrow cone angles, and reducing gain or sensitivity settings.
CONE ANGLE
– All transducers send down a signal that is shaped somewhat like a cone. Your
Digital Sonar easily switches from a 20-degree cone angle (good for general use) to a narrow
8-degree cone angle (good for water over 40’, or any time you need a more precise view of what
is below you). See the special section on Cone Angles below for more info. A feature unique to
the Marcum Digital Sonar is the “Sonar Footprint” that displays the actual extent of coverage by
your transducer while you are fishing. This data is displayed below the cone angle icon and
represents the diameter of the base of the transducer cone. This will keep you constantly
updated how much area is being covered by your Digital Sonar and will help you decide which
transducer angle best suits the conditions.
When the MarCum Digital Sonar is first turned on, it will be transmitting utilizing the 20-degree
setting. To switch from 20 degree to 8 degree, simply press the CONE ANGLE button once and
use the UP/DOWN buttons to highlight the desired selection. The cone angle changes as soon
as you highlight a selection and the Sonar Footprint will change with it.
TARGET ADJUST
– This feature allows the angler to change the size of the signals being
displayed without increasing the sensitivity. The TARGET ADJUST feature will give you the
smallest, signal size at “0”, and the signals displayed will get thicker as you increase the
TARGET ADJUST. This feature should be used in conjunction with the SENS to fine-tune your
display. Those who have a hard time seeing, as well as those who fish from a standing position
will really appreciate the “TARGET ADJUST” feature.
BATTERY METER
— This gauge indicates the voltage currently being produced by your battery.
The Marcum Digital Sonar needs at least 11 volts and preferably over 12 volts to properly
operate. If the voltage drops below 11 volts, you may see a decrease in performance. Recharg-
ing your battery after each use will maximize the life of your battery, and will ensure that your
Digital Sonar will run strong all day.
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