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  2. 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.

  3. 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.

  4. Beta angle - Wikipedia

    en.wikipedia.org/wiki/Beta_angle

    The value of a solar beta angle for a satellite in Earth orbit can be found using the equation = ⁡ [⁡ ⁡ ⁡ ⁡ ⁡ ⁡ ⁡ + ⁡ ⁡ ⁡ ()] where is the ecliptic true solar longitude, is the right ascension of ascending node (RAAN), is the orbit's inclination, and is the obliquity of the ecliptic (approximately 23.45 degrees for Earth at present).

  5. 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 ...

  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. 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.

  8. Radar altimeter - Wikipedia

    en.wikipedia.org/wiki/Radar_altimeter

    The dipole antenna of a radar altimeter of 1947. A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it takes a beam of radio waves to travel to ground, reflect, and return to the craft.

  9. 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.