Interphase Proble Operation Manual page 21

Track Plotter settings. In order to make changes to the
downlooking Chart display, you must go to a display where the
Chart display is on the right side of the display (such as the
Chart mode).
In addition to the fact that the softkey menu typically relates to
only the right side of the split screen displays, other features
such as Bottom Hardness and Fish Symbols will not appear in
Zoomed, Bottom Track or Bottom Locked displays.
Cone Angle & Area Covered to Side
The Probe's Cone Angle is approximately 12 degrees. The
Chart at right shows the approximate width of the cone at
different distances from the boat. Although 50% of the
acoustic radiation is concentrated within this cone, 50% is also
outside the cone which permits the Probe to detect targets
typically up to twice the cone angle, (i.e. 24 degrees). This
means, for example, that at 1,000 feet the Probe will typically
be able to see targets across a 420 foot width (210 feet each
side of center). See Figure at right. To estimate the diameter
of the 12 degree cone, divide the forward range by 5.
Example: At 100 feet forward of the transducer, the 12 degee
cone is approximately 20 feet in diameter.
In Split Screen Views, the Softkey Menu
Relates to the Right Side of the Display
1000
12 Degree
Cone
Angle
750
500
250
Distance
Forward
or Below
Boat
Width of 12 Degree Acoustic Beam
21
210
158
105
53
Probe can
typically
see targets
within this
area.