Sonar (short for voice navigation and range) is a
method in which sound waves are used to locate objects and map the environment.
In essence, a cluster of sound waves is directed towards any medium and
some waves are reflected from objects. It is used to measure the depth,
direction and speed of underwater objects such as submarines and ships with the
help of ultrasound.
Sonar was developed by Leonardo da Vinci in 1490 with
a simple ship. This technique later matured to combat submarines in
World War I, as submarines were the war-winning symbol at the time and had no
counter-technique.
Uses of sonar; not just the military field; It is also
used in bathymetry studies, pipeline inspections, search and rescue operations,
ocean exploration and academic research. In summary, Sonar technology, which
has been developed by taking inspiration from the working structure that
whales, bats and other animals have been using for years, provides advantages to
people in many areas.
Based on the sonar's
potential, whales can discern the size and movement of rocks from 60 meters
away. In fact, whales rely more on Sonar than their relatives, bait or sight.
By understanding the time elapsed and the speed of sound
before the wave returns, the receiver can evaluate the distance of the object
to the emitter. Although sonar works outdoors, it is most effective underwater.
A Sonar detects objects by emitting ultrasonic waves into the sea and detecting
reflected echoes. Sonar can detect and display the distribution, density and
movement of a school of fish at 360° or 180° in all directions.
How
Sonar Works
An active Sonar system consists of a display,
transducer, transmitter and receiver. An impulse is transmitted directly from
this transmitter and converted into a sound wave by the converter. The sound
will bounce back when the wave hits an object.
The echo then returns to the transducer, which
converts the sound into an electrical pulse amplified by the receiver. Then
this data is sent to the screen again. Sometimes the transducer helps to detect
sound waves and transmit them.
How to detect the sound
source and calculate the distance of the object from the origin. Sonar systems
using multiple hydrophone sensors record the intensity of the sound and phase
each time a ping hits a sensor. Phase is the timing delay
relative to the reference when receiving the sound wave. The sensor that
records the largest amplitude and has the least phase is the one closest to the
reflection point.
Another important factor in sonar performance is the
usage environment. The performance of sonar systems is variable and sometimes
unpredictable depending on the ocean's environment. Regular ocean studies are
critical for acoustic propagation models to provide accurate estimation of
ranges.
For example, one of the difficulty operations in Sonar
is scattering. This occurs from small objects in the body of water, from the
depth of the bottom to the height of the surface. Like the light emitted from
the light in the fog, the same applies to this water interference.
Types of Sonar
At one point, people developed Sonar with superior
resolution and range. The simplest Sonar systems consist of our ears and our
voice box. It's the same system we use when we scream at the top of a mountain
and hear our echo.
However, Sonar, developed by the army, can travel
thousands of kilometers. The sweep range allows the system to cover 80% of the
ocean beds from sound waves using only 4 vantage points. Despite the
effectiveness of light and the superior speed of radar, Sonar helps create
seafloor maps, develop sea charts, predict hazards and discover shipwrecks.
The purpose of sonar is to identify objects below the
surface that may cause difficulties to ships. Also, World War II brought
serious advances that highlighted the importance of war submarines and
underwater surveillance. From this progress, two main types of sonar emerged,
active and passive.
Active Sonar
Active Sonar relies on a projector and a receiver to
determine the target's range, direction, and relative movement. The
acoustic projector produces a sound wave that propagates outward and is then
reflected back by the target object. The receiver receives the reflected signal
and analyzes it.
An example of Active Sonar is
submarine ships. Submarines transmit acoustic energy and discover
surrounding objects through a time delay between receiving the echo. In
addition to being able to detect the presence of an object, the rise of advanced
modern tools allows us to determine the size, orientation and shape of an
object in great detail.
A remote-controlled underwater vehicle (ROV) uses
active sonar, which sends a sound wave of a specific frequency and then listens
for how long it takes for the sound wave to return as reflected from objects in
the water and on the seafloor. Multi-beam imaging sonar uses multiple beams of
sound to plot an image of what is in front of the ROV.
Passive Sonar
Passive Sonar is systems used in surveillance scenarios.
In this case, the method does not need a local transmitter as it listens for
waves transmitted by other devices.
This means the device picks up sounds from marine
life, ships, and other depth surfaces. However, machines in a passive system cannot
locate the sound source without the aid of listening devices. They must work
together to locate the transmitter before their presence is known (in a
military setting).
CHIRP Sonar
A Compressed High Intensity Radar Pulse, or CHIRP
sonar instrument, is often used for bottom monitoring and fish finding. Instead
of pinging a single frequency like traditional 2D sonar, Chirping devices
transmit a wide frequency range. With each pulse, the transducer begins to
vibrate at a low frequency and then modulates upwards to a high frequency for
the duration of the pulse.
Where Is Sonar Used?
While sonar technology is often known for its use by
the military, that's not its only use. Where is sonar used? Let's take a look.
1.
Bathymetric
Studies
Bathymetry is the study of water bodies, beds, or
floors, including the ocean, rivers, streams, and lakes. In this case, Sonar is
used to determine the depth of the ocean floors and to ensure safe navigation
on the waters.
2.
Pipeline
Inspections
Pipeline inspections can be made with high frequency,
sonar, side scanning technology. Gas and oil companies use Sonar to detect
damage, openings and rock dump integrity.
3.
Defense
Sonar is also used to detect the danger of explosion
underwater. As seafloors are exploited, it is important to identify the cables
and pipes within them. Finding unexploded bombs, mines and torpedoes is
important to overall safety and well-being. Sonar is also embedded in
submarines and ships to allow underwater communication with other entities.
4.
Safety, Public
Safety Divers and Search and Rescue
Sonar technology is often
used in search and rescue missions to make it easier and more efficient to find
evidence or victims of boating accidents or possible drowning in uncertain
waters. Sonar is used regularly in search and rescue. Side scanning
systems help locate corpses and guide divers to the recovery area.
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