Quadrature
Encyclopedia
Quadrature may refer to:
In signal processing:
In mathematics:
In physics:
In astronomy:
Quadrature may also refer to:
In signal processing:
- Quadrature amplitude modulationQuadrature amplitude modulationQuadrature amplitude modulation is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing the amplitudes of two carrier waves, using the amplitude-shift keying digital modulation scheme or amplitude modulation analog...
(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:
- Quadrature (mathematics)Quadrature (mathematics)Quadrature — historical mathematical term which means calculating of the area. Quadrature problems have served as one of the main sources of mathematical analysis.- History :...
, drawing a square with the same area as a given plane figure (squaring) or computing that area - Numerical integrationNumerical integrationIn 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 focuses on calculation of...
is often called 'numerical quadrature' or simply 'quadrature' - Gaussian quadratureGaussian quadratureIn numerical analysis, a quadrature rule is an approximation of the definite integral of a function, usually stated as a weighted sum of function values at specified points within the domain of integration....
, a special case of numerical integration
In physics:
- In Optical phase space, quadratures are operators which represent the real and imaginary parts of the complex amplitude
In astronomy:
- Quadrature (astronomy)Quadrature (astronomy)In astronomy, quadrature is that aspect of a heavenly body in which it makes a right angle with the direction of the Sun. It is applied especially to the apparent position of a superior planet, or of the Moon at first and last quarters....
, the position of a body (moon or planet) such that its elongation is 90º or 270º; i.e. the sun-earth-body angle is 90º
Quadrature may also refer to:
- In motion control, quadrature encoder is a rotary encoderRotary encoderA rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital code. The output of incremental encoders provides information about the motion of the shaft which is typically further processed...
or linear encoderLinear encoderA linear encoder is a sensor, transducer or readhead paired with a scale that encodes position. The sensor reads the scale in order to convert the encoded position into an analog or digital signal, which can then be decoded into position by a digital readout or motion controller.The encoder can be...
giving both the relative position and the direction of motion of a shaft