variableamplitude
Variable amplitude refers to a condition in which the magnitude of a waveform changes over time or along a spatial dimension. For a time-domain signal, the instantaneous amplitude A(t) defines how large the oscillations are at each moment, producing an envelope that bounds the oscillations. If A(t) is constant, the signal has fixed amplitude; when it varies, the amplitude is variable. A common mathematical form is x(t) = A(t) cos(ω0 t + φ(t)), where A(t) ≥ 0 represents the envelope and φ(t) is a phase function. When the amplitude is modulated by another signal, the process is called amplitude modulation (AM), widely used to transmit information by varying the carrier amplitude according to the modulating signal.
In engineering and physics, variable amplitude occurs in both transient and steady-state regimes. It can arise
Applications and considerations vary by field. In communications, variable amplitude interacts with dynamic range and distortion;