Attenuation distortion is the

distortion In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signa ...

of an analog signal that occurs during transmission when the transmission medium does not have a flat

frequency response In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of s ...

across the

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

of the medium or the

frequency spectrum The power spectrum S_(f) of a time series x(t) describes the distribution of power into frequency components composing that signal. According to Fourier analysis, any physical signal can be decomposed into a number of discrete frequencies, ...

of the signal.Rowe, Standord H. II, ''Network Technology & Service Integration'' (5th Edition), 2002, Prentice-Hall, Inc., 2002 Attenuation distortion occurs when some frequencies are

attenuate In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at vari ...

d more than other frequencies. When an analog signal of constant

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...

across its frequency spectrum suffers attenuation distortion, some frequencies of the received signal arrive being greater in amplitude (louder), relative to other frequencies. To overcome the effects of attenuation distortion,

communications circuit A telecommunication circuit is a path in a telecommunications network used to transmit information. Circuits have evolved over time from generally being built on physical connections between individual hardware cables, as in an analog phone swit ...

s have special equalization equipment attached at the ends of the circuit or in between, designed to attenuate the signal evenly across the frequency spectrum, or to allow the signal to be received at equal amplitude for all frequencies. Attenuation distortion can still occur in a properly equipped circuit if this equalization filter is not properly maintained or adjusted. In

DSL Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric dig ...

circuits, echoes due to

impedance mismatch In electronics, 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 minimize sign ...

often cause attenuation distortion so severe that some frequencies must be automatically mapped out and not used.

References

{{telcom-stub Telecommunications