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  2. GNSS reflectometry - Wikipedia

    en.wikipedia.org/wiki/GNSS_reflectometry

    As a GNSS satellite rises or sets, the elevation angle changes; the direct and reflected signals will generate an interference pattern. The frequency of this interference pattern can be used to extract the height of the antenna above the planar surface, the reflector height.

  3. Spherical coordinate system - Wikipedia

    en.wikipedia.org/wiki/Spherical_coordinate_system

    Even with these restrictions, if the polar angle (inclination) is 0° or 180°—elevation is −90° or +90°—then the azimuth angle is arbitrary; and if r is zero, both azimuth and polar angles are arbitrary. To define the coordinates as unique, the user can assert the convention that (in these cases) the arbitrary coordinates are set to zero.

  4. Horizontal coordinate system - Wikipedia

    en.wikipedia.org/wiki/Horizontal_coordinate_system

    Azimuth is measured eastward from the north point (sometimes from the south point) of the horizon; altitude is the angle above the horizon. The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane to define two angles of a spherical coordinate system: altitude and azimuth.

  5. Communications satellite - Wikipedia

    en.wikipedia.org/wiki/Communications_satellite

    Syncom 2 was the first communications satellite in a geosynchronous orbit. It revolved around the Earth once per day at constant speed, but because it still had north–south motion, special equipment was needed to track it. [19] Its successor, Syncom 3, launched on 19 July 1964, was the first geostationary communications satellite. Syncom 3 ...

  6. Omnidirectional antenna - Wikipedia

    en.wikipedia.org/wiki/Omnidirectional_antenna

    In radio communication, an omnidirectional antenna is a class of antenna which radiates equal radio power in all directions perpendicular to an axis (azimuthal directions), with power varying with angle to the axis (elevation angle), declining to zero on the axis.

  7. Angle of arrival - Wikipedia

    en.wikipedia.org/wiki/Angle_of_arrival

    The angle of arrival (AoA) of a signal is the direction from which the signal (e.g. radio, optical or acoustic) is received. [1] Measurement.

  8. Aperture (antenna) - Wikipedia

    en.wikipedia.org/wiki/Aperture_(antenna)

    Assume a plane wave from a particular direction (,), which are the azimuth and elevation angles relative to the array normal, has a power flux density ‖ ‖; this is the amount of power passing through a unit area normal to the direction of the plane wave of one square meter.

  9. Aerial photographic and satellite image interpretation

    en.wikipedia.org/wiki/Aerial_photographic_and...

    For a location which has an elevation lower than that of the datum plane, the original position will move closer to the central point of the image. [4] Figure 11. This diagram shows an example of displacement. A is the location that is lower than the datum plane. It moves inward to the central point. B is the location that is higher than the ...