Quadrature phase

Quadrature phase

Communication signals often have the form:

:A(t)cdot sin [2pi ft + phi(t)] , which is called "envelope-and-phase" form.

An equivalent representation, called "quadrature-carrier" form, is:

:I(t)cdot sin(2pi ft) + Q(t)cdot underbrace{cos(2pi ft)}_{sinleft(2pi ft + egin{matrix} frac{pi}{2} end{matrix} ight)},

where f, represents a carrier frequency, and:

:I(t) stackrel{mathrm{def{=} A(t)cdot cos [phi(t)] ,:Q(t) stackrel{mathrm{def{=} A(t)cdot sin [phi(t)] .,

A(t), and phi (t), represent possible modulation of a pure carrier wave: sin(2pi f t)., The modulation alters the original sin, component of the carrier, and creates a (new) cos, 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° (egin{matrix} frac{pi}{2} end{matrix} radians) out of phase, is referred to as the quadrature component.

Notes

See also

Phase (waves)#In-phase and quadrature (I&Q) components

Quadrature phase


Wikimedia Foundation. 2010.

См. также в других словарях:

  • Quadrature phase-shift keying — Phase shift keying Traduction terminée Phase shift keying → …   Wikipédia en Français

  • quadrature phase shift — ketvirtinis fazės pokytis statusas T sritis radioelektronika atitikmenys: angl. quadrature phase shift vok. Rechtwinkelphasenverschiebung, f rus. сдвиг по фазе на 90°, m pranc. quadrature de phase, f …   Radioelektronikos terminų žodynas

  • Quadrature Phase Shift Keying — Die Quadraturphasenumtastung oder Vierphasen Modulation (englisch Quadrature Phase Shift Keying, QPSK) ist ein digitales Modulationsverfahren in der Nachrichtentechnik. Mit QPSK können pro Sendesymbol zwei Bits übertragen werden. Dadurch… …   Deutsch Wikipedia

  • Phase shift keying — Traduction terminée Phase shift keying → …   Wikipédia en Français

  • Quadrature amplitude modulation — (QAM) (Pronounced IPA|kwa:m) is a modulation scheme which conveys data by changing ( modulating ) the amplitude of two carrier waves. These two waves, usually sinusoids, are out of phase with each other by 90° and are thus called quadrature… …   Wikipedia

  • quadrature — [ k(w)adratyr ] n. f. • 1407; bas lat. quadratura 1 ♦ Géom. Opération qui consiste à construire un carré équivalant à une aire donnée. Cour. La quadrature [ kadratyr ] du cercle : faux problème que les géomètres anciens tentaient de résoudre. Fig …   Encyclopédie Universelle

  • Phase (waves) — Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.[1] Contents 1 Formula 2 Phase shift 3 Phase difference …   Wikipedia

  • Quadrature — Quadrature, derived from Latin quadrare , may refer to: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… …   Wikipedia

  • Phase contrast microscopy — Phase contrast image of a cheek epithelial cell Phase contrast microscopy is an optical microscopy illumination technique of great importance to biologists in which small (invisible to the human eye) phase shifts in the light passing through a… …   Wikipedia

  • Phase-shift keying — Passband modulation v · d · e Analog modulation AM · …   Wikipedia


Поделиться ссылкой на выделенное

Прямая ссылка:
Нажмите правой клавишей мыши и выберите «Копировать ссылку»