Interpreting Your Vista Display; Forward View - Interphase Vista Operation Manual

Plane of Forward Scan is Angled 15 Degrees
Downward From Surface. Forward beam will
reach bottom at approx. 3.5 times depth
Beam Depth at Various Forward Ranges
Forward Range
Beam Depth =
Approx. .36 X
Forward Distance
vistman1
page 26
Depth
500
250
70
142
26
Interpreting The Vista's Forward
Display
The Interphase Vista provides a display which shows
acoustic echo returns from the underwater area below
and ahead of the vessel. The Phased Array Transducer
steers an acoustic beam over a forward arc of 90
degrees. As the Vista steers the beam to different
positions, it transmits a pulse of energy and then waits a
defined period of time (depending on the range selected)
to receive any return echoes. As the energy from this
acoustic beam strikes underwater objects or the bottom, a
small portion of the energy is reflected as an echo back
to the transducer. When the echo is received at the
transducer, it's converted into a small electrical signal
and processed for display on the Vista's LCD.
Since the Vista knows the direction in which it sent the
transmit pulse and the time it took to receive the return
echo, it can determine the location of the object or bottom
that created the return echo. As the Vista sequentially
steps the acoustic beam from the left to right and in front
of the vessel, the LCD display shows a continuously
updated display of the return echoes in their approximate
position in relation to the boat.
It's important to remember that to show underwater
objects, the Vista must be able to actually "see" them. It
can not show forward areas that are hidden from its field
of view or are hidden due to obstructions in the acoustic
beam's path through the water.

Forward View

The Vista scans from left to right across the boats bow.
The forward scanning elements in the transducer are
positioned so that the plane of the horizontal scan is
angled downward approximately 15 degrees from the
water's surface (see sketch at right). This downward
angle is designed to help reduce the effects of surface
noise clutter when the water is choppy and to allow
easier mounting of the transducer to the transom of
smaller boats.
As the acoustic sound beam is projected away from the
boat, the cross-sectional diameter of the beam increases.
At a range of approximately 3 to 3.5 times the depth of
the water the sound beam will begin intersecting the
bottom and some of the sound energy that intersects the
Tuesday, July 06, 1999 10:15