Quadrature phase
Encyclopedia
Two periodic waveforms whose phase
difference is
of their output period are said to have a quadrature phase relationship. The term is also used in communication systems to describe one of the components of orthogonal
decomposition.
A composite signal described by its envelope-and-phase form
can be decomposed to an equivalent quadrature-carrier(IQ) form as:
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. The component that is in phase with the original carrier is referred to as the in-phase component. The other component, which is always 90° (
radians) out of phase, is referred to as the quadrature component.
Phase (waves)
Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...
difference is
of their output period are said to have a quadrature phase relationship. The term is also used in communication systems to describe one of the components of orthogonalOrthogonality
Orthogonality occurs when two things can vary independently, they are uncorrelated, or they are perpendicular.-Mathematics:In mathematics, two vectors are orthogonal if they are perpendicular, i.e., they form a right angle...
decomposition.
A composite signal described by its envelope-and-phase form
can be decomposed to an equivalent quadrature-carrier(IQ) form as:where
represents a carrier frequencyCarrier wave
In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
, and:
and represent possible modulationModulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
of a pure carrier wave:
The modulation alters the original component of the carrier, and creates a (new) component, as shown above. The component that is in phase with the original carrier is referred to as the in-phase component. The other component, which is always 90° ( radians) out of phase, is referred to as the quadrature component.See also
- In-phase and quadrature (I&Q) components
- QuadratureQuadratureQuadrature may refer to:In signal processing:*Quadrature amplitude modulation , a modulation method of using both an carrier wave and a 'quadrature' carrier wave that is 90° out of phase with the main, or in-phase, carrier...
- 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...
- Constellation diagramConstellation diagramA constellation diagram is a representation of a signal modulated by a digital modulation scheme such as quadrature amplitude modulation or phase-shift keying. It displays the signal as a two-dimensional scatter diagram in the complex plane at symbol sampling instants...