What is an echo system?

An echo system is a system that uses echoes. Echo systems are used to determine location (aka echo location) by means of supersonic vibrations reflected from objects. Bats use this system to build up a picture of their environment and help them fly at night and near-total darkness.

Examples of man-made systems are radar (acronym for RADio Detection And Ranging, suitably, a palindrome). Radar was was first demonstrated in 1904 by Christian Hülsmeyer, who used radio waves to detect "the presence of distant metallic objects". He was able to demonstrate the feasibility of detecting the presence of a ship in dense fog, but not its distance.

Prior to the 2nd World War progress was slow until the mid-1930s, when Sir Robert Watson-Watt, descendant of the great inventor, James Watt, was approached by the British Air Ministry regarding the feasibility of producing a 'death ray'. Watson-Watt, with the help of his assistant Arnold Wilkins, quickly established that such an invention was not feasible and drafted, in February 1935, a report titled 'The Detection of Aircraft by Radio Methods'.

The system was developed by the British at the outbreak of WWII, to detect incoming enemy planes and give their own planes greater navigational accuracy. The British efforts led to their defeating of the vastly superior German Luftwaffe in the Battle of Britain.

Other man-made echo systems include sonar (SOund Navigation And Ranging), used by ships and submarines to determine their position in relation to other objects;

echocardiography (investigation by means of ultrasound of certain internal parts of the heart and they way in which they move in order to detect disease); and echoencephalography (investigation of the brain by means of ultrasound waves beamed through the head).