Interphase Color Twinscope, Operation Manual

Page: 71 / 88

71
Bait
40ft Forward Range, Water Depth of 12 Ft
240ft Forward Range, Bottom Depth of 12 ft.
Fish or Bait
Bottom
Bottom
Bait
The top picture and resulting screen display shows a boat in
12 feet of water. The
Twinscope’s forward range is set to
40 ft. Notice on the scan picture on the right side of the
display, the bottom is just starting to show at about 35 to 40
ft in front. A school of fish or bait is off to the port side of
the vessel at a forward distance of about 14 feet and
additional fish or bait appears directly in front of the boat at
a distance of only a few feet. Also notice the fish or bait
near the bottom on the downlooking mode on the left side of
the display.
In the lower picture and resulting screen display, notice that
even in shallow depths of 12 ft the
Twinscope is detecting
targets at a forward distance of approximately 200 feet.
When looking far forward in shallow situations such as this,
it is advisable to adjust the gain manually. Otherwise the
Auto gain feature will reduce the gain because of the strong
close-in bottom reflections.
On the following page, two bottom situations are sketched
along with the resulting
Twinscope Display.
Noise and Sensitivity Adjustments
The Twinscope features an AUTO sensitivity feature
where it continuously adjusts the sensitivity to achieve the
optimum picture quality. The sensitivity can also be
adjusted manually to allow for a reduction in sensitivity to
minimize the effect of screen noise, or to increase the
sensitivity to show weaker targets.
In the forward scanning modes, the sensitivity setting is
especially important as too little sensitivity will cause a loss
of target detection and too much sensitivity will cause an
increase in screen noise. In the AUTO mode, the
Twinscope increases the forward gain until there is a certain
density of targets on the display. In most situations the
AUTO gain mode works well, but manual adjustments will
often be required to get the optimum picture - especially
when looking far ahead in shallow water.