Noise
Interference, unwanted signal. That part of a TV or radio transmission that is not wanted; it is usually caused by thermal effects in the atmosphere. The quality of a signal received from a satellite is expressed as a ratio between the signal strength (carrier) and the noise level, sometimes abbreviated as C/N ratio.

Noise Temperature
The equivalent of thermal noise, expressed in terms of degrees Kelvin. When choosing a receiving system it is important to take into account the noise temperature of the antenna as well as that of every component involved in the processing of the signal received by the parabolic dish. The sum total of the various temperatures is referred to as the noise temperature of the system. It is equivalent to the noise ratio of the entire receiving system. The higher the noise temperature, the worse is the reception.