Quadrature may refer to:

In signal processing:

• Quadrature amplitude modulation (QAM), a modulation method of using both an (in-phase) carrier wave and a 'quadrature' carrier wave that is 90° out of phase with the main, or in-phase, 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 phase-shift keying (QPSK), a phase-shift keying of using four quadrate points on the constellation diagram, equispaced around a circle

In mathematics:

In physics:

• In Optical phase space, quadratures are operators which represent the real and imaginary parts of the complex amplitude

In astronomy:

• Quadrature (astronomy), the position of a body (moon or planet) such that its elongation is 90° or 270°; i.e. the sun-earth-body angle is 90°

Quadrature may also refer to:

• 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

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Last modified on 26 February 2013, at 16:39