Noise figures [two-port linear transducers]

A short tutorial description of noise figures for two-port linear transducers and entire receiver systems is presented. Due to the long history of the use of noise figures to specify noise performance, numerous definitions have evolved. The relationships between the various noise figures definitions found in the literature are specified and tables are provided as a cross reference to the notation and naming conventions used in the references. It is shown that the noise performance of a receiver system can be described by either the standard system noise figure or the operating-system noise figure. The results are equivalent, and the noise performance description can be transformed from one noise figure to the other