Look up quadrature in Wiktionary, the free dictionary.

Quadrature, derived from Latin quadrare, may refer to: Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ...

In signal processing:

• Quadrature amplitude modulation (QAM), a modulation method of using both a carrier wave and a 'quadrature' carrier wave that is 90° out of phase with the main carrier
• Quadrature phase, oscillations that are said to be in quadrature if they are separated in phase by 90° (π/2, or λ/4)
• Quadrature filter, the analytic signal of a real-valued filter
• Quadrature coupler, see under chapter five in Power dividers and directional couplers

In mathematics: “QAM” redirects here. ... Communication signals often have the form: where represents a carrier frequency, and: and represent possible modulation of a pure carrier wave: . The modulation alters the original component of the carrier, and creates a [new] component, as shown above. ... In signal processing a quadrature filter is the analytic signal of a real-valued filter : If the quadrature filter is applied to a signal , the result is which implies that is the analytic signal of . ... Power dividers and directional couplers are passive devices used in the field of radio technology. ...

• Quadrature of the circle (also squaring the circle), in geometry, the problem of constructing a square and circle of equal area, impossible using only an unmarked straight-edge and compass
• Summing in quadrature means summing the squares of numbers, then taking the square root, as used in error analysis
• Numerical quadrature, the numerical calculation of the area under a curve, or more generally, using numerical integration to calculate a definite integral

Quadrature may also refer to: The quadrature of the circle, better known as squaring the circle, is a classical problem of mathematics, or more specifically, of geometry. ... In numerical analysis, numerical integration constitutes a broad family of algorithms for calculating the numerical value of a definite integral, and by extension, the term is also sometimes used to describe the numerical solution of differential equations. ... This article deals with the concept of an integral in calculus. ...

• In motion control, quadrature encoder is a rotary encoder or linear encoder giving both the relative position and the direction of motion of a shaft
• In astronomy, quadrature occurs when two celestial bodies appear 90° apart from one another as viewed from a third celestial body. As an example, the Moon and the Sun are in quadrature with respect to the Earth when the Moon is in its exact first quarter or last quarter phases. The symbol for astronomical quadrature is a hollow square

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