Infrasonic includes the eruption of volcanoes and Earthquakes. Ultrasonic is above the human hearing limit, and they have a frequency of 20k Hz. However, Infrasonic is not preferred in the Sonar technique, especially in active SONAR, because infrasonic are not able to move in the water. But both are very useful as infrasonic can travel more distance, and ultrasonic provide more resolution. SONARs have great use in modern warfare, especially for the navy, preventing them from revealing the location to locate submarines as radar is not efficient in deep waters.
Torpedoes are also equipped with active and passive SONARs to guide them directly and accurately to the target. SONARs are also used to locate or hide the explosive mines. SONARs are even used for underwater communication.
The use of sonar is not only limited to the navy; helicopters and aircraft are also equipped with a special kind of sonar which can identify submarines from the air. SONARs are the only thing over which authorities depend for the surveillance and security of their seas and oceans. Sound waves travel differently than water because the bladder of fish is filled with air and has high density compared to seawater.
The process used to measure the depth of water beneath boats and ships is echo sounding; it is a type of active sonar. It is the traveling of a sound wave directly to the sea bed.
Sonar What is a sonar? They can also use the return echo to identify the object that the sound reflected off of. Whales, dolphins, and bats use echolocation , a natural type of sonar, in order to identify and locate their prey. This recording is of an active sonar that is tracking a close target.
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The angle of the sensor then shifts as the next ultrasonic wave is transmitted. As soon as the ultrasonic waves are sent, the Sonar immediately switches to the receiving state and listen for the returning ultrasonic echoes. The searchlight Sonar has a detection range of 6 degrees. By emitting ultrasound and then rotating the beam sequentially, it can detect schools of fish with fairly good precision.
Because of the very narrow detection angle, it takes time for the sensor to make a full rotation, and as the boat is moving, some areas might stay undetected. While the overall detection speed is slow, the miniaturisation of the sensor part makes it possible to install Searchlight Sonars on small boats.
The scanning Sonar emits ultrasonic waves all around the ship for degrees simultaneously and can detect and display the returning echoes instantly.
The detection speed is much faster than that of the scanning Sonar, and all the surroundings can be detected instantly.
You can detect and evaluate the movements of fish swimming at high speed in the sea, such as bonito and tuna. The system fires ultrasonic waves in all directions around the ship in a single burst, and can instantly detect and display everything around the ship. Sensors installed on the bottom of the ship use ultrasonic waves to instantaneously search a degree area under the ship. The principle is the same as the searchlight Sonar, but the sector scanning Sonar searches in degree steps, so the Sonar is 4 to 7 times faster than the searchlight Sonar.
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