Interphase iScan V90, Operation Manual

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Important Note: One of the biggest problems encountered
with adjusting forward scanning sonars is too much gain -
especially in the vertical forward view. If there are no targets
directly in front of the boat, the natural tendency is to continue
to increase the gain. Usually this results in a noisy display and
is not necessary. In general, if you can see the bottom between
3 and 4 times the depth forward (for example in 10 feet of
water, seeing the bottom forward 30 to 40 feet) the gain is
adequate. (On forward ranges below 200 feet, it’s
recommended to keep the gain below the number 10.)
Screen Cursor
The iScan V90 has a useful screen cursor feature that can
show the approximate depth and range from the vessel to any
target on a forward scanning display.
Pressing the CURSR button will toggle the screen cursor and
it’s
CURSOR DATA BOX on and off. The drawing at right
shows the CURSOR activated and the CURSOR DATA
BOX in the lower right corner of the display.
To use the screen
Cursor feature, press the CURSR button to
activate and then use the NAV button to move the cursor to the
desired location on the display. Wherever the cursor is
placed, the
CURSOR DATA BOX will display the
approximate DEPTH and RANGE from the vessel to that
location.
It is important to realize that the depth information in the
CURSOR DATA BOX is the result of a calculation based on
the angle of the acoustic beam below the surface of the water.
Because each transducer installation is unique and the vessel
may be moving up and down in the water - the angle of the
acoustic beam is only approximately known. Therefore, the
calculated depth is also only an approximation and should not
be relied upon during critical situations.
It is also important to understand that the calculated depth in
the
CURSOR DATA BOX is the depth at the center of the
Iscan V90’s 12-degree acoustic beam angle as shown in the
diagram at right. Notice that the beam expands as it gets
further from the boat. For example, at 1,000 feet the beam
angle has a diameter of greater than 100 feet! However, the
cursor calculates the depth at the centerline of the beam as
shown.
Range
Surface
Depth
12-Degree
Beam Angle
CURSOR DEPTH AND RANGE
CURSR
VERT
VIDEO
DOWN DATA
RANGE GAIN
PWR
FORWARD LOOKING SONAR
30 to 40 Ft
10 Ft
CURSR
VERT VIDEO
DOWN DATA
RANGE GAIN
PWR
FORWARD LOOKING SONAR
Depth 24.5Ft
Range 76.0Ft
Cursor
Cursor Data Box
CURSR
VERT
VIDEO
DOWN DATA
RANGE
GAIN
PWR
FORWARD LOOKING SONAR
Depth 24.5Ft
Range 76.0Ft
Use Nav Key to Move Cursor