SONAR

**What is Sonar?**
====Sonar is short for //Sound Navigation and Ranging.// It is used for exploring and mapping the ocean. It also detects how deep the ocean is or how far away an object is in the water. Radar and light waves are not used because sound travels further. It is a navigational technique used to gather information around a surrounding environment.There are two types of sonar, active and passive.====

**How does it work?**
====Passive sonar involves listening for sounds generated by ships or submarines. It has been used since the 1400s and uses hydroacoustics which is a series of properties that govern how sound moves underwater. Passive sonar systems just process, listen and display sound.====

====Active sonar is used when a ship sends out a pulse of sound in a range of frequencies (also called a "ping") and then listens for the reflecting echo to return. An active sonar system has a sound transmitter, receiver, a signal processor and a display unit that can send a pulse of sound electronically. Using explosives is also a form of creating pulses mechanically.==== ====When an electrical impulse is converted into an acoustic sound pulse and it strikes an object, sound rebounds or echoes. The echo strikes the receiver and is converted back into an electrical signal. This signal is then processed and sent to a display unit. To measure the distance of an object, the time from transmission of a pulse to reception of the echo is measured and converted into a range by knowing the speed of sound in water. The speed of sound in water is approximately 4800 feet per second. When active sonar is used to measure distances it is known as echo sounding.====

**What is it used for?**
====Sonar is used by the military to look for submarines and by ocean scientists to find out the depth of water and map the contours of the ocean bottom. Sonar is also used by fishermen for locating fish and mapping terrain on the bottom of lakes and fishing sites. Dolphins and bats also use a form of echolocation which is similar to using sonar to find food.====

**Why is it related to sound and waves? **
====Sonar is related to sound and waves because it uses sound waves to detect distances and objects. When these waves hit the objects, it reflects and reports back to the transmitter. ====