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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 astronomy:

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

Quadrature may also refer to: