High accuracy settling time measurements figure 1

electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

signal processing Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, Scalar potential, potential fields, Seismic tomograph ...

, and video, ringing is

oscillation Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

of a signal, particularly in the step response (the response to a sudden change in input). Often ringing is undesirable, but not always, as in the case of resonant inductive coupling. It is also known as hunting. It is also known as ripple, particularly in electricity or in

frequency domain In mathematics, physics, electronics, control systems engineering, and statistics, the frequency domain refers to the analysis of mathematical functions or signals with respect to frequency (and possibly phase), rather than time, as in time ser ...

response.

Electrical circuits

electrical Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

circuits, ringing is an

of a

voltage Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...

or current. Ringing can be undesirable because it causes extra current to flow, thereby wasting energy and causing extra heating of the components; it can cause unwanted

electromagnetic radiation In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...

to be emitted; it can increase settling time for the desired final state; and it may cause unwanted triggering of bistable elements in

digital circuit In theoretical computer science, a circuit is a model of computation in which input values proceed through a sequence of gates, each of which computes a function. Circuits of this kind provide a generalization of Boolean circuits and a mathematica ...

s. Ringy communications circuits may suffer falsing. Two electrical sources of this ringing are: # A resonant

transient response In electrical engineering and mechanical engineering, a transient response is the response of a system to a change from an equilibrium or a steady state. The transient response is not necessarily tied to abrupt events but to any event that affe ...

due to undesired parasitic capacitances and inductances in the circuit creating a resonant

frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

. This is often the damping response following overshoot or undershoot, and thus these related concepts are at times conflated. This ringing can be reduced by a slower

slew rate In electronics and electromagnetics, slew rate is defined as the change of voltage or current, or any other electrical or electromagnetic quantity, per unit of time. Expressed in SI units, the unit of measurement is given as the change per seco ...

and possibly eliminated by critically dampening the resonance. # Signal reflection, which may be minimized by

impedance matching In electrical engineering, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. Often, the desired value is selected to maximize power transfer or ...

. While either issue can be addressed with a series termination resistor, a resistor cannot simultaneously critically damp the response and perfectly match the impedance without losing some power on the series resistor, so a bypass capacitor may be preferred.

Analog video

In a

cathode-ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms on an oscilloscope, a ...

(CRT)

video Video is an Electronics, electronic medium for the recording, copying, playback, broadcasting, and display of moving picture, moving image, visual Media (communication), media. Video was first developed for mechanical television systems, whi ...

circuit, electrical ringing causes closely spaced repeated ghosts of a vertical or diagonal edge where dark changes to light or vice versa, going from left to right, whereby the electron beam's intensity overshoots and undershoots the desired intensity there a few times instead of settling quickly. This bouncing could occur anywhere in the electronics or cabling and is often caused by or accentuated by a too high setting of the sharpness control.

Analog audio

Ringing can affect audio equipment in a number of ways. Audio amplifiers can produce ringing depending on their design, although the transients that can produce such ringing rarely occur in audio signals. Transducers (i.e., microphones and

loudspeakers A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...

) can also ring. Mechanical ringing is more of a problem with loudspeakers as the moving masses are larger and less easily damped, but unless extreme they are difficult to audibly identify.

Signal processing

, "ringing" may refer to ringing artifacts: spurious signals near sharp transitions. These have a number of causes, and occur for instance in

JPEG JPEG ( , short for Joint Photographic Experts Group and sometimes retroactively referred to as JPEG 1) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degr ...

compression and as pre-echo in some

digital audio Digital audio is a representation of sound recorded in, or converted into, digital signal (signal processing), digital form. In digital audio, the sound wave of the audio signal is typically encoded as numerical sampling (signal processing), ...

compression. Signals constructed as only a partial (not infinite)

Fourier series A Fourier series () is an Series expansion, expansion of a periodic function into a sum of trigonometric functions. The Fourier series is an example of a trigonometric series. By expressing a function as a sum of sines and cosines, many problems ...

of a function containing discontinuities (e.g. when applying a brickwall lowpass filter to a

square wave Square wave may refer to: *Square wave (waveform) A square wave is a non-sinusoidal waveform, non-sinusoidal periodic waveform in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same ...

) create a ringing error called the Gibbs phenomenon ''before'' and ''after'' each discontinuity.

References

External links