Oceans & Coasts: Multibeam Sonar
How Sonar Works
To COMPLETE this quest, visit one or more of the links above then produce a Creative Reflection about SONAR and how it works. Show a video or diagram to demonstrate that you understand how it works.Be sure to upload to your website.
Website
SOund NAvigation and Ranging—SONAR—is used to find and identify objects in water. It is also used to determine water depth (bathymetry). An acoustic signal or pulse of sound is transmitted into the water by a sort of underwater speaker known as a transducer. It was first used during World War I to detect submarines. Scientists use two general types of sonar—active and passive.
Active sonar emits an acoustic signal or pulse of sound into the water. They can be mounted on the keel of a ship of the hull of a submarine. Higher sound frequences provide better image resolution but the acoustic energy pulses travels short distance. Lower sound frequencies provide a lower image resolution but the acoustic energy pulses travels great distances. Passive sonar systems are used to detect noise from marine objects like ships, submarines, and marine animals (whales). It does not emit its own signal which can be an advantage for military vessels that do not want to be found for covert missions.
Marine researchers commonly use side-scan sonar technology to search for and detect objects on the seafloor. The side-scan beam is oriented to the side of the ship, and usually slightly downward. It continuously records the return echo, creating a "picture" of the sea floor (dark and light areas). Hard objects protruding from the bottom send a strong echo and create a dark image. Shadows and soft areas, such as mud and sand, send weaker echoes, thus creating a light image.
Website
SOund NAvigation and Ranging—SONAR—is used to find and identify objects in water. It is also used to determine water depth (bathymetry). An acoustic signal or pulse of sound is transmitted into the water by a sort of underwater speaker known as a transducer. It was first used during World War I to detect submarines. Scientists use two general types of sonar—active and passive.
Active sonar emits an acoustic signal or pulse of sound into the water. They can be mounted on the keel of a ship of the hull of a submarine. Higher sound frequences provide better image resolution but the acoustic energy pulses travels short distance. Lower sound frequencies provide a lower image resolution but the acoustic energy pulses travels great distances. Passive sonar systems are used to detect noise from marine objects like ships, submarines, and marine animals (whales). It does not emit its own signal which can be an advantage for military vessels that do not want to be found for covert missions.
Marine researchers commonly use side-scan sonar technology to search for and detect objects on the seafloor. The side-scan beam is oriented to the side of the ship, and usually slightly downward. It continuously records the return echo, creating a "picture" of the sea floor (dark and light areas). Hard objects protruding from the bottom send a strong echo and create a dark image. Shadows and soft areas, such as mud and sand, send weaker echoes, thus creating a light image.