Файл:In-phase and quadrature components of angle modulation.gif

Alternative description:

Example of how an angle-modulated sinusoid can be decomposed into or synthesized from two amplitude-modulated sinusoids. The picture shows a modulation by non-linearly increasing the phase angle of the carrier from 0 to [math]\displaystyle{ \lt semantics\gt \lt mrow class="MJX-TeXAtom-ORD"\gt \lt mstyle displaystyle="true" scriptlevel="0"\gt \lt mstyle displaystyle="false" scriptlevel="1"\gt \lt mi\gt π\lt !-- π --\gt \lt /mi\gt \lt mrow class="MJX-TeXAtom-ORD"\gt \lt mo\gt /\lt /mo\gt \lt /mrow\gt \lt mn\gt 2\lt /mn\gt \lt /mstyle\gt \lt /mstyle\gt \lt /mrow\gt \lt annotation encoding="application/x-tex"\gt {\displaystyle \scriptstyle \pi /2}\lt /annotation\gt \lt /semantics\gt }[/math]<img alt="{\displaystyle \scriptstyle \pi /2}" aria-hidden="true" class="mwe-math-fallback-image-inline mw-invert" src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f9b1eaa2cc59190b49d082c19a74b22c7e0f0e20" style="vertical-align: -0.671ex; width:2.586ex; height:2.176ex;"/> over the interval 0 < t < 16. The two AM sinusoids have the same nominal frequency as the carrier and are offset in phase by one-quarter cycle ([math]\displaystyle{ \lt semantics\gt \lt mrow class="MJX-TeXAtom-ORD"\gt \lt mstyle displaystyle="true" scriptlevel="0"\gt \lt mstyle displaystyle="false" scriptlevel="1"\gt \lt mi\gt π\lt !-- π --\gt \lt /mi\gt \lt mrow class="MJX-TeXAtom-ORD"\gt \lt mo\gt /\lt /mo\gt \lt /mrow\gt \lt mn\gt 2\lt /mn\gt \lt /mstyle\gt \lt /mstyle\gt \lt /mrow\gt \lt annotation encoding="application/x-tex"\gt {\displaystyle \scriptstyle \pi /2}\lt /annotation\gt \lt /semantics\gt }[/math]<img alt="{\displaystyle \scriptstyle \pi /2}" aria-hidden="true" class="mwe-math-fallback-image-inline mw-invert" src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f9b1eaa2cc59190b49d082c19a74b22c7e0f0e20" style="vertical-align: -0.671ex; width:2.586ex; height:2.176ex;"/> radians). They are known as the in-phase component (I, thin blue, decreasing) and the quadrature component (Q, thin red, increasing). In some contexts it is more convenient to refer to just the enveloping factors of the AM-signals (thick red and blue lines) by those component terms.