the data transmission impairment

the data transmission impairment

1. Attenuation

   • The received signal should have sufficient strength to be intelligently interpreted by a receiver
   • A signal should be maintained at a level higher than the noise so that error will not be generated.
   • Attenuation is an increasing function of frequency, with more attenuation at higher frequency than at lower frequency.
   • The impairment is caused by the strength of signals that degrades with distance over a transmission link

2. Delay distortion

   • The velocity of propogation of a signal through a guided medium varies with frequencies

3. Noise

   • Thermal noise: This noise is a function of temperature and bandwidth
     • thermal noise = K(constant) *temperature *bandwith.
   • Impairment occurs when an unwanted signal is inserted between transmission and reception
   • Intermodulation noise: This noise is caused by nonlinearity in the transmission system f 1; f2 frequencies could produce a signal at f1 + f2 or ABS (f1 − f2) and affect the frequencies at f1 + f2 or ABS (f1 − f2).
   • Cross talk: This type of noise is caused by electrical coupling in the near by twisted pair or by unwanted signal picked by microwave antennas.
   • Impulse noise: Irregular pulses and short duration of relative high amplitude cause impulse noise. This noise is also caused by lightning and faults in the communication system.