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Sensitivity Adjustment
The screen display shown on the left page is typical when
the AUTO sensitivity is used. In this mode, the
Advantage finds the bottom and adjusts the receiver’s
sensitivity to give a noise free picture from the bottom to
the surface. As it is often difficult for the Advantage to
separate small fish from noise signals, most experienced
fishermen choose to adjust the receiver sensitivity
manually in order to show more possible fish and bait
targets. (see picture at right).
When adjusting the sensitivity manually, increase the gain
(sensitivity) until the screen shows a significant amount
of noise, then slowly turn down the sensitivity until only a
small amount of noise remains. With practice you will
quickly be able to adjust the sensitivity to your personal
preference.
Transducer Ringing
On the shallow ranges, a dark band will show at the top of
the display (at the surface). You may notice some noise
or “ringing” at the top of the display just beneath the boat
icon. Do not be concerned. This noise is caused by the
transmitted ultrasonic signal sent by the Advantage’s
transducer. This type of noise or ringing is inherent in all
Sonars and is the ultimate limit of the shallow depth
reading detectable by the instrument. The transducer
“ring” is greater with the 50 kHz frequency and increases
with large transmit power. For the shallower ranges, it is
suggested that you use the 200 kHz frequency and lower
transmit output power.
Surface Noise
In some situations there can be a significant amount of
surface clutter caused by schools of bait, rough water or
shallow temperature inversions. If large enough, these
conditions can cause the Advantage’s automatic Range
and automatic Gain circuits to think that the surface
clutter is the bottom. When this happens, the Advantage
will try to lock onto the surface clutter instead of the real
bottom. In conditions of severe surface noise or clutter,
it is recommended that you adjust the depth range and
receiver sensitivity manually.
Manual Gain Increased to Show More
Suspended Targets
Transducer Ringing. Note that surface
ringing is more severe on 50 kHz frequency.
Ringing
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