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  2. Line-of-sight propagation - Wikipedia

    en.wikipedia.org/wiki/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. [1] Electromagnetic transmission includes light emissions traveling in a straight line. The rays or waves may be diffracted ...

  3. Long distance observations - Wikipedia

    en.wikipedia.org/wiki/Long_distance_observations

    Other lines of sight: The longest line of sight in the British Isles is from Snowdon to Merrick – 232 km. This was photographed by Kris Williams in 2015. [42] The longest line of sight that has been photographed within the USA is Denali from Mount Sanford at 370 km distance. [43] Other long-distance photographs include:

  4. Line of sight - Wikipedia

    en.wikipedia.org/wiki/Line_of_sight

    The line of sight, also known as visual axis or sightline (also sight line), is an imaginary line between a viewer/ observer / spectator 's eye (s) and a subject of interest, or their relative direction. [1] The subject may be any definable object taken note of or to be taken note of by the observer, at any distance more than least distance of ...

  5. Radial velocity - Wikipedia

    en.wikipedia.org/wiki/Radial_Velocity

    The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity onto the relative direction or line-of-sight (LOS) connecting the two points.

  6. Over-the-horizon radar - Wikipedia

    en.wikipedia.org/wiki/Over-the-horizon_radar

    The frequency of radio waves used by most radars, in the form of microwaves, travel in straight lines.This generally limits the detection range of radar systems to objects on their horizon (generally referred to as "line of sight" since the aircraft must be at least theoretically visible to a person at the location and elevation of the radar transmitter) due to the curvature of the Earth.

  7. Fresnel zone - Wikipedia

    en.wikipedia.org/wiki/Fresnel_zone

    A Fresnel zone (English: / freɪˈnɛl / fray-NEL), named after physicist Augustin-Jean Fresnel, is one of a series of confocal prolate ellipsoidal regions of space between and around a transmitter and a receiver. The primary wave will travel in a relative straight line from the transmitter to the receiver. Aberrant transmitted radio, sound, or ...

  8. Rifleman's rule - Wikipedia

    en.wikipedia.org/wiki/Rifleman's_rule

    This means that the rifle sight setting for any range from 0 to 500 meters is available. The sight adjustment procedure can be followed step-by-step. 1. Determine the slant range to the target. Assume that a range finder is available that determines that the target is exactly 300 meters distance. 2. Determine the elevation angle of the target.

  9. Optical telegraph - Wikipedia

    en.wikipedia.org/wiki/Optical_telegraph

    An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals (a form of optical communication). There are two main types of such systems; the semaphore telegraph which uses pivoted indicator arms and conveys information according to the direction the indicators point ...