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In telecommunication, degradation, is the loss of quality of an electronic signal, which may be categorized as either "''graceful''" or "''catastrophic''", and has the following meanings: #The deterioration in quality, level, or standard of performance of a functional unit. #In communications, a condition in which one or more of the required performance parameters fall outside predetermined limits, resulting in a lower quality of service. There are several forms and causes of degradation in electric signals, both in the time domain and in the physical domain, including runt pulse, voltage spike, jitter, wander, swim, drift, glitch, ringing, crosstalk, antenna effect (not the same antenna effect as in IC manufacturing), and phase noise. 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: # Weather or environmental conditions. # Terrain # Other signals. # Faulty or poor quality equipment. ==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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Degradation (telecommunications)」の詳細全文を読む スポンサード リンク
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