Principle Of Operation - Interphase Sea Scout Operation Manual

Principle of Operat
The Sea Scout Forward Scanning Sonar uses a
proprietary phased array acoustic technology first
developed for marine use by Interphase Technologies.
Known as "phased array
ultrasound technology", its capabilities have been
proven in the medical industry for many years. The
amazing video-like images provided by medical
ultrasound equipment are familiar to most people and
clearly demonstrate the technology's ability to show
highly defined images in a "real time" or "live action"
mode. Interphase has taken this same technology and
modified it for use in the marine market.
Present day fish finders/ depth sounders all work on a
principle developed during W.W. II, called SONAR,
where acoustic pulses are used to detect the presence
and range or distance to an underwater object. During
the 1950's, several devices which used sonar principles
were developed and marketed to fishing and boating
enthusiasts to detect the distance to the bottom (depth)
and to indicate the presence of any intervening
submerged objects - such as fish.
The Sea Scout's transducer does not contain just one
piezoelectric ceramic element like most fishfinders.
The Sea Scout's transducer contains an array of 7
elements that look forward and one element that looks
straight down, to give you the conventional past-history
display like most other fishfinders/depthsounders.
An acoustic array is a group of piezoelectric ceramic
elements that are precisely sized and spaced. Each
element will send and receive acoustic pulses, as when
used in more conventional single element depth
sounders. However, when all elements in the array are
sending or receiving acoustic energy at the same time,
the entire array behaves like a single larger element
with one important difference: the ability of the array to
concentrate its acoustic energy in different directions,
depending on the different "phasing" of the signals
applied or received by each element. Depending on the
signal phasing of the array, acoustic beams can be
directed in an almost unlimited number of directions.
For example, using an 8 element phased array
transducer, the Sea Scout is capable of steering the
acoustic beam in any of 90 different directions.
Conventional fixed-beam technology would require the
use of 90 different elements to duplicate this capability.
ion The resulting transducer would be much too large and
costly to be of any practical use.
Since the acoustic beam in the phased array is steered
electronically, requiring no moving parts, it can be
quickly and reliably scanned and re-scanned over a
large area. When displayed, the changing information
between subsequent scans takes on an almost animated
quality - for example, showing movement of
underwater targets such as fish or rapidly changing
bottom conditions.
In addition to its ability to electronically steer an
acoustic beam, the phased array has other advantages
over fixed-beam technologies, such as: allowing the
user to adjust the transducer scan width, to search large
areas limited only by the physics of the speed of sound
in water (5,000 feet/second), and the ability to provide
nearly real time or live action underwater views.
When operating, the Sea Scout converts a small amount
of electrical current from your battery into ultrasonic
sound pulses, which are then fed to the phased array
transducer. These acoustic pulses travel out from the
transducer in a cone shaped pattern, called the cone
angle. When the sound pulse strikes an underwater
object, it is reflected back (echo return), received by the
transducer and converted back into small electrical
impulses. These impulses are amplified, then displayed
as an image on the LCD screen after processing by the
unit's microprocessor.
The strength of the echo, the depth of the object, and
the angle of the transducer's beam all affect how the
image appears on the display. Other factors which
affect the image include boat speed relative to the
movement, position of the underwater target and the
number of objects reflecting pulses back to the Sea
Scout.
The Sea Scout's forward looking display is new and
learning to properly interpret scanning sonar takes both
patience and experience; but once mastered, the Sea
Scout can offer tremendous operational advantages
over conventional fixed-beam depth sounders.
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