Altimeters - general
Altimeters are used in many cases, particularly the pilots, rock climbers and paratroopers. Thanks to them, you can read the height above sea level and even below the surface of the earth. The altimeters shall be divided into two main types. One is a pressure altimeter, while the second device to radar. The first of these is a well-barometer, which is an instrument to measure air pressure. The pressure decreases with height, so you can also specify a height. Radar altimeter sends a wave down, which is reflected from the surface and returns to the receiver. The measurement between the sending and receiving a pulse that allows the height between the ground and even air.