SweepSignal

SweepSignal is a term used in signal processing to describe a time-varying electrical, acoustic, or radio frequency signal whose instantaneous frequency traverses a defined range over a finite duration. The concept is widely employed for characterizing linear and nonlinear system responses, particularly in audio and acoustics, where a swept sine or chirp can excite a system across its bandwidth.

A SweepSignal is typically defined by parameters such as start frequency f1, end frequency f2, duration T, and sweep type. The instantaneous frequency f(t) follows a chosen profile, commonly linear or exponential (logarithmic) sweep. In an exponential sweep, f(t) increases multiplicatively according to f(t) = f1*(f2/f1)^{t/T}. The amplitude envelope may be constant or tapered with windowing to reduce spectral leakage and to control the signal’s crest factor. A proper sampling rate, equal to or greater than twice the maximum frequency, is required, and the signal is often scaled for desired loudness or dynamic range.

In practice, SweepSignal is used to measure impulse responses by deconvolving the recorded response with an inverse filter, or to estimate room acoustics, loudspeaker, or microphone characteristics. The Farina logarithmic sweep method is a notable application that separates linear and nonlinear contributions. Implementations appear in digital audio workstations, scientific computing environments, and hardware signal generators, with common tools in MATLAB and Python (NumPy/SciPy).

Related concepts include chirp signals, sine sweeps, and system identification techniques.