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Sonar's Role in Locating Underwater Mountains
Transcript of Sonar's Role in Locating Underwater Mountains
What is SONAR?
Sonar is an acronym for Sound Navigation And Ranging. Sonar was invented to detect submarines and map the ocean floor as well as finding ancient artifacts. It could tell how far away submarines and other underwater objects were.
Sonar is a system for tracking down objects under the ocean and for measuring the water’s depth by releasing sound pulses and measuring their return after being reflected. Using sonar was basically making sense of the echo. The pulses also showed whether the ground was soft, hard, sandy, or covered in coral, sea grass, or other soft plants based on the intensity of the echo.
Sonar's Sound Waves
Locating Underwater Mountains
By: Katherine Ma, Sangita Kunapuli, Manogna Rajanala
Side scan sonar is a type of sonar that creates a picture or image of the sea floor and measures how strong the return echo is. It is used to map hills, valleys and other physical features. Rock reflects more sound than sand, and darker areas have a louder echo than lighter areas.
Sonar uses active sound waves, instead of radio waves like in radios. An active sound wave uses a sound called a ping, which lasts for a fraction of a second, and then receives a returning echo. The waves are typically sent out in a fan shape, their width 4x as long as the ocean’s depth. The area is scanned several times, with the waves being passed over the same spot, and then a picture made from the data collected from the scans is made.
Uses of Sonar
As well as locating and mapping things on the seafloor, sonar also has other uses. For one, it is used to develop nautical charts. A nautical chart is a picture representing an area of the sea and adjacent coastal regions. Sonar is also put to use by locating underwater hazards to navigation. Sonar is used to search for and map objects on sea floor. For example, shipwrecks or airplane crash debris. Another way sonar is helpful is it can examine and inspect things located underwater, such as pipelines, cables, and bridge foundations.
A fathometer is used with sonar to collect data. Using a fathometer is a system, similar to sonar, that measures the time it takes for the echo to return from the bottom of the sea. It is a sonic depth finder. It converts the time and the speed of the sonar wave into the distance from the bottom (s*t=d), using a unit of measure specially adapted for underwater speeds, the fathom (one fathom= 6 feet, or about 1.8 meters).
Two types of sonar
There are two types of sonar: passive and active. Passive was developed first. It picks up sounds using electronic listening equipment. It relies on listening for noise generated by the target vessel (submarines). The other type of sonar is the active sonar, which is characterized by a “ping”. The ping is the sound wave. This produces and emits a burst of sound or the “ping”. It is generated by the searcher. It bounces off objects, giving a picture of the object in the path of the sound wave. These types of sonar are used to “see” objects or determine distance.
Underwater mountains found by side scan sonar.
Sonar radar detection.
What is SONAR? cont.