Eagle Electronics FISHMARK 320 - Manual (Page 44)

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9. If you are drifting at a very low speed or anchored, you are not mov-
ing fast enough for a fish to return the tell-tale fish arch signal. As you
drift over a fish, or as a fish swims through the transducer's signal
cone, the fish echo will appear as a straight line suspended between the
surface and the bottom.
10. To turn off the unit, press and hold PWR key for three seconds.
Sonar Operations
As you can see from the quick reference, basic operation is pretty easy, right
out of the box. If you are a sonar novice, try operating the unit with the fac-
tory defaults until you get a feel for how it's working.
As you're learning the basics, there is one setting you might want to tinker
with from time to time — Sensitivity.
Sensitivity controls the unit's ability to pick up echoes. If you want to see
more detail, try increasing the sensitivity, a little at a time. There are
situations when too much clutter appears on the screen. Decreasing the
sensitivity can reduce the clutter and show the strongest fish echoes, if
fish are present. As you change the sensitivity setting, you can see the
difference on the chart as it scrolls.
You can change the sensitivity level whether you are in Auto Sensitiv-
ity mode or Manual Sensitivity mode. The adjustment method works
the same in both modes, but it gives you slightly different results.
Adjusting sensitivity in Auto Sensitivity Mode is similar to manually ad-
justing a car's speed with the accelerator pedal while cruise control is on.
You can tell the car to run faster, but when you let off the gas the cruise
control
automatically keeps you from running slower than the minimum
speed setting. In the sonar unit, auto mode will let you increase sensitiv-
ity to 100 percent, but the unit will
limit your minimum setting. This pre-
vents you from turning sensitivity down too low to allow automatic bot-
tom tracking. When you change the setting with auto turned on, the unit
will continue to track the bottom and make minor adjustments to the sen-
sitivity level, with a bias toward the setting you selected.