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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 (relative to a specific Datum (geodesy), datum), the slant distance equals the horizontal distance. An example of slant range is the distance to an aircraft flying at high altitude with respect to that of the radar antenna (electronics), antenna. The slant range (1) is the hypotenuse of the triangle represented by the altitude of the aircraft and the distance between the radar antenna and the aircraft's Course (navigation), ground track (point (3) on the earth directly below the aircraft). In the absence of altitude information, for example from a height finder, the aircraft location would be plotted further (2) from the antenna than its actual ground track. See also *Ranging *Spherical range *Line-of-sight_propagation References * * Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 (relative to a specific Datum (geodesy), datum), the slant distance equals the horizontal distance. An example of slant range is the distance to an aircraft flying at high altitude with respect to that of the radar antenna (electronics), antenna. The slant range (1) is the hypotenuse of the triangle represented by the altitude of the aircraft and the distance between the radar antenna and the aircraft's Course (navigation), ground track (point (3) on the earth directly below the aircraft). In the absence of altitude information, for example from a height finder, the aircraft location would be plotted further (2) from the antenna than its actual ground track. See also *Ranging *Spherical range *Line-of-sight_propagation References * * Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and terrain. The term ''RADAR'' was coined in 1940 by the United States Navy as an acronym for "radio detection and ranging". The term ''radar'' has since entered English and other languages as an anacronym, a common noun, losing all capitalization. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwave domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relative Direction (geometry)
In geometry, a position or position vector, also known as location vector or radius vector, is a Euclidean vector that represents a point ''P'' in space. Its length represents the distance in relation to an arbitrary reference origin ''O'', and its direction represents the angular orientation with respect to given reference axes. Usually denoted x, r, or s, it corresponds to the straight line segment from ''O'' to ''P''. In other words, it is the displacement or translation that maps the origin to ''P'': :\mathbf=\overrightarrow. The term position vector is used mostly in the fields of differential geometry, mechanics and occasionally vector calculus. Frequently this is used in two-dimensional or three-dimensional space, but can be easily generalized to Euclidean spaces and affine spaces of any dimension.Keller, F. J., Gettys, W. E. et al. (1993), p. 28–29. Relative position The relative position of a point ''Q'' with respect to point ''P'' is the Euclidean vector res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Level (coordinate)
Vertical position or vertical location is a position along a vertical direction (the plumb line direction) above or below a given vertical datum (a reference level surface, such as mean sea level). Vertical distance or vertical separation is the distance between two vertical positions. Many vertical coordinates exist for expressing vertical position: depth, height, altitude, elevation, etc. Points lying on an equigeopotential surface are said to be on the same vertical level, as in a water level. A function with domain along the vertical line is called a ''vertical distribution'' or ''vertical profile''. Definitions The International Organization for Standardization (ISO), more specifically ISO 19111, offers the following two definitions: * ''depth'': "distance of a point from a chosen reference surface measured downward along a line perpendicular to that surface." * ''height'': "distance of a point from a chosen reference surface measured upward along a line perpendicular to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Datum (geodesy)
A geodetic datum or geodetic system (also: geodetic reference datum, geodetic reference system, or geodetic reference frame, or terrestrial reference frame) is a global datum reference or reference frame for unambiguously representing the position of locations on Earth by means of either geodetic coordinates (and related vertical coordinates) or geocentric coordinates. DatumsThe plural is not "data" in this case are crucial to any technology or technique based on spatial location, including geodesy, navigation, surveying, geographic information systems, remote sensing, and cartography. A horizontal datum is used to measure a horizontal position, across the Earth's surface, in latitude and longitude or another related coordinate system. A ''vertical datum'' is used to measure the elevation or depth relative to a standard origin, such as mean sea level (MSL). A three-dimensional datum enables the expression of both horizontal and vertical position components in a unified form. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna (electronics)
In radio-frequency engineering, an antenna (American English) or aerial (British English) is an electronic device that converts an alternating current, alternating electric current into radio waves (transmitting), or radio waves into an electric current (receiving). It is the interface between radio waves Radio propagation, propagating through space and electric currents moving in metal Electrical conductor, conductors, used with a transmitter or receiver (radio), receiver. In transmission (telecommunications), transmission, a radio transmitter supplies an electric current to the antenna's Terminal (electronics), terminals, and the antenna radiates the energy from the current as electromagnetic radiation, electromagnetic waves (radio waves). In receiver (radio), reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplifier, amplified. Antennas are essential components ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Course (navigation)
In navigation, the course of a watercraft or aircraft is the cardinal direction in which the craft is to be Steering, steered. The course is to be distinguished from the ''Heading (navigation), heading'', which is the direction where the watercraft's Bow (watercraft), bow or the aircraft's Nose cone, nose is pointed. The path that a vessel follows is called a track or, in the case of aircraft, ground track (also known as ''course made good'' or ''course over the ground''). The intended track is a route. Discussion For ships and aircraft, routes are typically Great-circle distance, straight-line segments between Waypoint, waypoints. A navigator determines the ''bearing'' (the compass direction from the craft's current position) of the next waypoint. Because water currents or wind can cause a craft to drift off course, a navigator sets a ''course to steer'' that compensates for drift. The helmsman or pilot points the craft on a ''heading'' that corresponds to the course to s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Height Finder
A height finder is a ground-based aircraft altitude measuring device. Early height finders were optical range finder devices combined with simple mechanical computers, while later systems migrated to radar 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 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 radar is a type of 2-dimensional radar that measures altitude of a target. The operator slews the antenna toward a desired bearing, identifies a target e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ranging
Length measurement, distance measurement, or range measurement (ranging) all refer to the many ways in which length, distance, or range can be measured. The most commonly used approaches are the rulers, followed by transit-time methods and the interferometer methods based upon the speed of light. Surveying is one ancient use of measuring long distances. For tiny objects such as crystals and diffraction gratings, diffraction is used with X-ray light, or even electron beams. Measurement techniques for three-dimensional structures very small in every dimension use specialized instruments such as ion microscopy coupled with intensive computer modeling. These techniques are employed, for example, to measure the tiny features on wafers during the manufacture of chips. Standard rulers The ruler the simplest kind of length measurement tool: lengths are defined by printed marks or engravings on a stick. The metre was initially defined using a ruler before more accurate methods bec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spherical Range
The great-circle distance, orthodromic distance, or spherical distance is the distance between two points on a sphere, measured along the great-circle arc between them. This arc is the shortest path between the two points on the surface of the sphere. (By comparison, the shortest path passing through the sphere's interior is the chord between the points.) On a curved surface, the concept of straight lines is replaced by a more general concept of geodesics, curves which are locally straight with respect to the surface. Geodesics on the sphere are great circles, circles whose center coincides with the center of the sphere. Any two distinct points on a sphere that are not antipodal (diametrically opposite) both lie on a unique great circle, which the points separate into two arcs; the length of the shorter arc is the great-circle distance between the points. This arc length is proportional to the central angle between the points, which if measured in radians can be scaled up ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line-of-sight Propagation
Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. Electromagnetic transmission includes light emissions traveling in a straight line. The rays or waves may be diffracted, refracted, reflected, or absorbed by the atmosphere and obstructions with material and generally cannot travel over the horizon or behind obstacles. In contrast to line-of-sight propagation, at low frequency (below approximately 3 MHz) due to diffraction, radio waves can travel as ground waves, which follow the contour of the Earth. This enables AM radio stations to transmit beyond the horizon. Additionally, frequencies in the shortwave bands between approximately 1 and 30 MHz, can be refracted back to Earth by the ionosphere, called skywave or "skip" propagation, thus giving radio transmissions in this range a potentially global reach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
