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 an ...

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 detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

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 A coincidence rangefinder or coincidence telemeter is a type of rangefinder that uses mechanical and optical principles to allow an operator to determine the distance to a visible object. There are subtypes split-image telemeter, inverted image, ...

used to determine the altitude of an aircraft (actually the

slant range In radio electronics, especially radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacec ...

from the emplacement which was combined with the angle of sight, in a mechanical computer, to produce altitude), used to direct anti-aircraft guns. 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 In mathematics, a plane is a Euclidean (flat), two- dimensional surface that extends indefinitely. A plane is the two-dimensional analogue of a point (zero dimensions), a line (one dimension) and three-dimensional space. Planes can arise as ...

that measures

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

of a target. The operator slews the antenna toward a desired bearing, identifies a target echo at a desired range on the RHI display (RHI = range height indicator), 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 3-D, 3D, or 3d may refer to: Science, technology, and mathematics Relating to three-dimensionality * Three-dimensional space ** 3D computer graphics, computer graphics that use a three-dimensional representation of geometric data ** 3D film, a ...

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