Signaalamplitudes

Signaalamplitudes refer to the magnitudes of signals in signal processing and analysis. They quantify how strong a signal is at a given time or across a waveform. The term covers several related measures, including instantaneous amplitude, peak amplitude, and root-mean-square (RMS) amplitude, which are used in engineering, acoustics, and communications.

For a real-valued time signal x(t) that can be written as x(t) = A(t) cos(ωt + φ), A(t) is the instantaneous amplitude or envelope; for a pure sinusoid x(t) = A cos(ωt + φ), A is the peak amplitude, i.e., the maximum deviation from zero. The RMS amplitude, A_rms = A / √2 for a sine wave; more generally, RMS = sqrt((1/T) ∫ x^2(t) dt). For complex signals, the magnitude of the analytic signal or the envelope provides the instantaneous amplitude.

In the frequency domain, the amplitude spectrum is the magnitude of the Fourier transform, showing how much each frequency contributes to the signal's overall energy. Amplitudes are closely tied to power; for a signal with resistance R, average power is P = V_rms^2 / R, with V_rms = A_rms for a sinusoid.

Applications include amplitude modulation in communications, envelope detection in radio receivers, audio level control, and sensor measurements. Practical considerations include clipping and saturation, dynamic range, calibration, and measurement bandwidth, all of which affect observed amplitudes.