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An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. [1] The measurement of altitude is called altimetry , which is related to the term bathymetry , the measurement of depth under water.
The dipole antenna of a radar altimeter of 1947. A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it takes a beam of radio waves to travel to ground, reflect, and return to the craft.
The greater the altitude, the lower the pressure. When a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is a type of altimeter called a pressure altimeter or barometric altimeter. A pressure altimeter is the altimeter found in most aircraft, and skydivers use wrist-mounted versions for similar ...
Pressure altimeters must be calibrated prior to flight to register the pressure as an altitude above sea level. The instrument case of the altimeter is airtight and has a vent to the static port. Inside the instrument, there is a sealed aneroid barometer. As pressure in the case decreases, the internal barometer expands, which is mechanically ...
The Bendix Central Air Data Computer contains complex electromechanical mechanisms. Electrical-mechanical air data computers were developed in the early 1950s to provide a central source of airspeed, altitude, and other signals to avionic systems that needed this data.
The QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 hPa when the aircraft is at aerodrome or touchdown elevation. [2] QNH: The pressure set on the subscale of the altimeter so that the instrument indicates its height above sea level (the altimeter will read runway elevation when the aircraft is on the runway). [1]
The exact definition and reference datum varies according to the context (e.g., aviation, geometry, geographical survey, sport, or atmospheric pressure). Although the term altitude is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage.
Farhang-e-Asifiya (Urdu: فرہنگ آصفیہ, lit. 'The Dictionary of Asif') is an Urdu-to-Urdu dictionary compiled by Syed Ahmad Dehlvi. [1] It has more than 60,000 entries in four volumes. [2] It was first published in January 1901 by Rifah-e-Aam Press in Lahore, present-day Pakistan. [3] [4]