SONAR uses sound waves to detect obstacles in water. It was invented in 1906 and is used by navies and whales. Active SONAR sends out sound waves and detects echoes to accurately map locations, but reveals the user's position. Passive SONAR listens for other sound waves without emitting any, making it better for stealth but less accurate unless combined with triangulation. While effective for mapping underwater, high-powered naval SONAR can damage cetaceans' hearing and cause hemorrhaging.

1. The Role of Waves in SONAR
Ruary Thompson

2. SONAR
Used to stand for:
SOund Navigation And Ranging
(Now is accepted as a word itself)
• Invented & first used by Lewis Nixon in 1906 to detect icebergs.
• Sound waves travel through water, refract, and let instruments
know where obstacles are.
• Utilizes sound waves, NOT electromagnetic waves.
• Sound waves are longitudinal.
• Usually connected to the navy, but also used in nature
(Whales/dolphins)

3. Active SONAR
• Active SONAR involves sending sound waves to detect obstacles.
• Accurate, used by whales as well as naval crafts.
• However, can give away position.
http://www.solarnavigator.net/images/Sonar_sound_ping_send_return_effect_principle.JPG

4. Passive SONAR
• Involves silently listening to other sound waves
• Not accurate unless triangulated
• Triangulation: multiple receptors allow you to pinpoint a
noise source
• Silent, good in combat situations (i.e. submarine fights)
http://www.solarnavigator.net/images/Sonar_sound_ping_send_return_effect_principle.JPG

5. More on SONAR
• Uses sound waves which travel better than light waves in water.
• Navy sonar can actually kill cetaceans (Dolphins and whales). It
deafens then, and causes them to hemorrhage.
• However, active is quite accurate at mapping sea floors:
http://oceanservice.noaa.gov/facts/sonarstellwegen.jpg
Image of a shipwreck rendered through Active Sonar

6. Bibliography
Bellis, M. (2012). The History of Sonar. Retrieved 9 24, 2012, from About:
http://inventors.about.com/od/sstartinventions/a/sonar_history.htm
Leo, K. (2011). Navy Sonar and Acoustic Impacts. Retrieved 9 24, 2012, from Koholaleo:
http://www.koholaleo.com/noise_pollution__impacts.html
NOAA. (2011, 11 17). Sonar uses sound waves to 'see' in the water. Retrieved 9 24, 2012,
from National Oceanic and Atmospheric Administration:
http://oceanservice.noaa.gov/facts/sonar.html