In telecommunication

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

, degradation, which may be categorized as either "graceful" or "catastrophic", has the following meanings:

1. The deterioration in quality, level, or standard of performance of a functional unit.
2. In communications
   Telecommunication
   Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
   
   , a condition in which one or more of the required performance parameters fall outside predetermined limits, resulting in a lower quality of service
   Quality of service
   The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
   
   .

There are several forms and causes of degradation in electric signals, both in the time domain

Time domain

Time domain is a term used to describe the analysis of mathematical functions, physical signals or time series of economic or environmental data, with respect to time. In the time domain, the signal or function's value is known for all real numbers, for the case of continuous time, or at various...

 and in the physical domain, including runt pulse

Runt pulse

In digital circuits, a runt pulse is a narrow pulse that,due to non-zero rise and fall times of the signal, does not reach a validhigh or low level...

, voltage spike

Voltage spike

In electrical engineering, spikes are fast, short duration electrical transients in voltage , current , or transferred energy in an electrical circuit....

, jitter

Jitter

Jitter is the undesired deviation from true periodicity of an assumed periodic signal in electronics and telecommunications, often in relation to a reference clock source. Jitter may be observed in characteristics such as the frequency of successive pulses, the signal amplitude, or phase of...

, wander

Wander

In telecommunication, wander are long-term low-frequency random variations of the significant instants of a digital signal from their ideal positions. Phase variations with a frequency content above 10 Hertz are considered jitter, while those with a frequency below 10 Hz are referred to as wander....

, swim, drift

Drift (telecommunication)

In telecommunication, a drift is a comparatively long-term change in an attribute, value, or operational parameter of a system or equipment. The drift should be characterized, such as "diurnal frequency drift" and "output level drift." Drift is usually undesirable and unidirectional, but may be...

, glitch

Glitch

A glitch is a short-lived fault in a system. It is often used to describe a transient fault that corrects itself, and is therefore difficult to troubleshoot...

, ringing

Ringing (signal)

In electronics, signal processing, and video, ringing is unwanted oscillation of a signal, particularly in the step response...

, crosstalk, antenna effect (not the same antenna effect

Antenna effect

The antenna effect, more formally plasma induced gate oxide damage, is an effect that can potentially cause yield and reliability problems during the manufacture of MOS integrated circuits. Fabs normally supply antenna rules, which are rules that must be obeyed to avoid this problem. A violation...

 as in IC manufacturing), and phase noise

Phase noise

Phase noise is the frequency domain representation of rapid, short-term, random fluctuations in the phase of a waveform, caused by time domain instabilities...

.

Degradation usually refers to reduction in quality of an analog or digital signal. When a signal is being transmitted or received, it undergoes changes which are undesirable. These changes are called degradation. Degradation is usually caused by:

1. Weather or environmental conditions.
2. Terrain
3. Other signals.
4. Faulty or poor quality equipments.

Weather conditions

A signal has two important factors: frequency and wavelength. If weather is fine and temperature is normal, the signal can be transmitted within given frequency and wavelength limits. The signal travels with velocity c ≤ 3*10⁸ m/s, which is equal to the speed of light. For frequency f Hz and wavelength λ m, we have

f = c/λ.

So, when weather conditions deteriorate, frequency f has to be increased. This causes the wavelength λ to decrease, which means that the signal then travels lesser distance.