In phase

From Free net encyclopedia

In phase can refer to any of the following things.

Phase angle

A periodic signal (usually electromagnetic in nature) is said to be in phase with another signal when both have the same phase. In other words, they begin their cycle simultaneously.

Whether the term is hyphenated or not depends on its use:

• "The in-phase signals prevent distortion"
• "The two signals are in phase with each other"

See also: out of phase, phase difference, Phase cancellation

In-phase Component

Communication signals often have the form:

<math>A(t)\cdot \cos[\omega t + \phi(t)] \equiv I(t)\cdot \cos(\omega t) - Q(t)\cdot \sin(\omega t)\,</math>

where <math>\omega\,</math> represents a carrier frequency, and:

<math>I(t) = A(t)\cdot \cos[\phi(t)]</math>

<math>Q(t) = A(t)\cdot \sin[\phi(t)]</math>

<math>A(t)\,</math> and <math>\phi (t)\,</math> represent possible modulation of a pure carrier wave: <math>\cos(\omega t)\,</math>. The modulation alters the original <math>\cos\,</math> component of the carrier, and creates a [new] <math>\sin\,</math> 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° (<math>\begin{matrix} \frac{\pi}{2} \end{matrix}</math> radians) out of phase, is referred to as the quadrature component.Template:Disambig