Quadrature
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Quadrature, derived from Latin quadrare, is a term with various meanings:
- in astronomy, the line tangent to an object's orbit defines the object's quadrature. For a circular orbit, this line is 90°, or a quarter of a circle, away from the center of the orbit.
- in geometry, quadrature of the circle or squaring the circle is the problem of constructing a square and circle of equal area, impossible using only an unmarked straightedge and compass
- in mathematics, quadrature is a synonym for numerical integration. Summing in quadrature means summing the squares of numbers, then taking the square root, as used in error analysis
- in telecommunications, quadrature refers to signals which are separated in phase by 90° (π/2 radians)
- Quadrature amplitude modulation (QAM) is the encoding of information into a carrier wave by variation of the amplitude of both the carrier wave and a 'quadrature' carrier that is 90° out of phase with the main carrier in accordance with two input signals.