Sonar

SOund Navigation And Ranging

What is a Sonar?

• A Sonar is a system that uses transmitted and reflected underwater objects or measure the distances underwater.

What is it’s Purpose?

• It has been used form submarine and mine detection, depth detection , commercial fishing, driving safety and communication at sea.

How does it Communicate?

• The sonar device will send out a subsurface sound wave and then listens for returning echoes, the sound data is relayed to the human operators by a loudspeaker or by being displayed on a monitor.

Who invented it?• As early as 1822, Daniel Colloden used an underwater

bell to calculate the speed of sound underwater in Lake Geneva, Switzerland. This early research led to the invention of dedicated sonar devices by other inventors.

• Lewis Nixon invented the very first Sonar type listening device in 1906 for a way to detect icebergs. Interest was increased in the Sonar during World War I when there was a need to be able to detect submarines. The first Sonar devices were passive meaning no signals were sent out.

After the Sonar was Introduced• In 1918 Britain and U.S. had both built active systems,

which sent out and received signals.

Two types of Sonar’s

• There are two types of Sonar’s one is called Active and another one is called Passive.

• An Active Sonar creates a pulse of sound often called a “ping” and then listens for reflections of the pulse.

• A Passive Sonar listens without transmitting. They are usually military one but a few are used Scientific. Passive sonar systems usually have large sonic databases, and a computer system uses these databases to identify classes of ships such as the speed of the ship, or the type of weapon released and even particular ships.

History of the Sonar

• The Sonar started out as a military application during the Second World War. In fact, it was originally referred to as the Anti-Submarine Detection Investigation Committee.

• The use of sonar was directed against German submarines. Following their failure in the Battle of Britain, the Germans began to use submarine warfare in an attempt to cut off the British ships, and Britain depended on these ships for vital war materials and food. The use of sonar allowed the powerful British surface fleet to detect the direction and depth of these submarines and destroy many of them.

Radar

RAdio Detection And Ranging

What is a Radar?

• A Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain.

History on Radar• The history of the radar starts

with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. During World War II, The Radar played a critical role in the British victory in the Battle of Britain. The British victory in this battle was largely due to a series of radar stations that had been built along the southern and eastern coasts of Britain in 1939.

Who invented it?

• Heinrich Rudolf Hertz was a German physicist who clarified and expanded James Clerk Maxwell's electromagnetic theory of light, which was first demonstrated by David Edward Hughes using non-rigorous trial and error procedures.

WWII• During World War II, battles

were won by the side that was first to spot enemy airplanes, ships, or submarines.

• To give the Allies an edge, British and American scientists developed radar technology to "see" for hundreds of miles, even at night. The research that went into improving radar helped set the stage for post-war research into the transistor.

Types of Radars• Land-Based Air Defense Radars.• Battlefield, Missile Control, and Ground Surveillance Radars. • Naval and Coastal Surveillance, and Navigation• Naval Fire-Control Radars• Airborne Surveillance Radars• Airborne Fire-Control Radars• Spaceborne Radar Systems• Military Air Traffic Control (ATC), Instrumentation and Ranging Radars. • Simple Pulse Radar• Moving-Target Indication (MTI) Radar• Airborne Moving-Target Indication (AMTI) Radar• Pulse Doppler Radar.• High-Range Resolution Radar• Pulse-Compression Radar• Synthetic Aperture Radar (SAR)• Inverse Synthetic Aperture Radar (ISAR)• Side-Looking Airborne Radar (SLAR)• Tracking Radar• Track-While-Scan (TWS) Radar• Electronically Scanned Phased-Array Radar• Frequency-modulated Continuous-wave (FM-CW) Radar• High Frequency Over-the-Horizon (HF OTH) Radar• Scatterometer • Precipitation Radar• Cloud Profile Radar