A height finder is a ground-based aircraft altitude measuring device. Early height finders were optical

range finder A rangefinder (also rangefinding telemeter, depending on the context) is a device used to measure distances to remote objects. Originally optical devices used in surveying, they soon found applications in other fields, such as photography, t ...

devices combined with simple

mechanical computer A mechanical computer is a computer built from mechanical components such as levers and gears rather than electronic components. The most common examples are adding machines and mechanical counters, which use the turning of gears to incremen ...

s, while later systems migrated to

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

devices. The unique vertical oscillating motion of height finder radars led to them also being known as nodding radar. Devices combining both optics and radar were deployed by the U.S. Military.

Optical

In World War II, a height finder was an optical rangefinder used to determine the altitude of an aircraft (actually the

slant range In radio electronics, especially radar terminology, slant range or slant distance is the distance along the relative direction (geometry), relative direction between two points. If the two points are at the same level (coordinate), level (relati ...

from the emplacement which was combined with the angle of sight, in a mechanical computer, to produce altitude), used to direct

anti-aircraft gun Anti-aircraft warfare (AAW) is the counter to aerial warfare and includes "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It encompasses surface-based, subsurface ( submarine-launched), and air-ba ...

s. Examples of American and Japanese versions exist. In the Soviet Union it was usually combined with optical rangefinders.

Radar

A height finder

is a type of

2-dimensional A two-dimensional space is a mathematical space with two dimensions, meaning points have two degrees of freedom: their locations can be locally described with two coordinates or they can move in two independent directions. Common two-dimensional s ...

that measures

altitude Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum (geodesy), datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometr ...

of a target. The operator slews the antenna toward a desired bearing, identifies a target echo at a desired range on the range height indicator display, then bisects the target with a cursor that is scaled to indicate the approximate altitude of the target. Such systems often complement 2-dimensional radars which find distance and direction (search radar); thus using two 2-dimensional systems to obtain a 3-dimensional aerial picture. Height finding radars of the 1960s and 70s were distinguished by their antenna being tall, but narrow. As beam shape is a function of antenna shape, the height finder beam was flat and wide horizontally (i.e., not very good at determining bearing to the target), but very thin vertically, allowing accurate measurement of elevation angle, thus altitude. Modern

3D radar 3D radar provides for radar ranging and direction in three dimensions. In addition to range, the more common two-dimensional radar provides only azimuth for direction, whereas the 3D radar also provides elevation. Applications include weather rada ...

sets find both azimuth and elevation, making separate height finder radars largely obsolete.

References

External links

A page about a type of height finders found in surface-to-air missile sites (German)
{{DEFAULTSORT:Height Finder Radar

Optical

Radar

See also

References

External links