Name the type of transmission impairments. Briefly explain the different types of noise with examples.

(i) Thermal noise: Thermal noise is due to thermal agitation of electrons. It presents in all electronic devices and transmission media and a function of temperature.

The amount of thermal noise to be found in a bandwidth of 1Hz in any device is,

(ii) Intermediation noise: When signals at different frequencies share the same transmission medium, the result may be intermediation noise. The effect of intermediation noise is to produce signals at a frequency that is the sum or difference of the two original frequencies or multiples of those frequencies.
For example, the mixing of signals at frequencies f1  and f2

  might produce energy at the frequency  f1+f2

(iii) Crosstalk: Crosstalk is an unwanted coupling between signal paths. It can occur by electrical coupling between twisted pair or co-axial cable lines carrying multiple signals. Typically crosstalk is of the same order of magnitudes as or less than thermal noise.

(iv) Impulse noise: Impulse noise is noncontiguous consisting of irregular pulses of short duration and of relatively high amplitude. It is generated from a variety of causes, including external electromagnetic, disturbances, such as lighting and faults and flows in the communications system.