Interphase Twinscope Operation Manual page 56

Other Features
Press the soft key labeled "OTHER" to bring up a sub-
menu that will allow you to create a split screen zoom or
bottom locked picture, have the Twinscope interpret the
display and show fish symbols or adjust the display
scrolling speed.
Zoom & Bottom Track & Bottom Lock
(Split Screen displays)
When using the Chart display (conventional down
looking view), the Twinscope can also display a split
screen high resolution zoom of any 25% of the depth
range, or can show a split screen Bottom Track or
Bottom Lock display. The high resolution Zoom is
very useful when looking for extra detail on the bottom
or in areas above the bottom. Because the Twinscope
Zoom Bar
uses an Interphase unique 4X over-sampling technique,
the zoom actually shows more data than the non-
zoomed picture. Fishermen have long used the bottom
locking features when fishing over a rocky bottom or
when fishing in rough surface conditions. In the
Bottom Track mode, a zoomed view of the bottom is
shown on the left side of the split screen display.
Regardless of changes in bottom depth, the left side
tracks it and keeps the zoomed bottom picture in view.
In the Bottom Lock mode, the bottom is forced to
appear as a straight horizontal line across the bottom of
Split Screen Zoom Display
the left side of the LCD while any targets close to the
bottom are displayed above the bottom line. Over rough
bottoms or in rough conditions, this feature is extremely
useful to eliminate rapidly changing bottom depths from
the display and to show only suspended targets close to
the bottom.
Press the soft key labeled "ZOOM " to activate the
split screen high resolution zoom function. The left side
of the LCD screen now shows the zoomed area, while
the right side continues to show the conventional depth
display. Hold down the "ZOOM " soft key (or rotate
the front panel knob) and notice the vertical bar moving
downward in the center of the display which shows the
depth area that is being "zoomed". By using the
"ZOOM " and "ZOOM " soft keys, you can zoom in
on particular depth areas. The Zoom feature expands
any 25% section of the current depth range on the left
Split Screen Bottom Tracking Display
half of the screen, or effectively magnifies the section
selected by the zoom bar by 400%.
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