In the first of this thesis the nature of random noise, whicharise and theoretically cannot be eliminated from radio receivers, is described.
Nyquist equation, pertaining to the amount of noise generated ina resistor, is rederived by a simple method. The original equation asderived by Nyquist, is found to be valid, only, for physicallyrealizable impedances of the minimum reactance type.
The general problem of a passive electric network excited by randomsources is treated; a useful principle is developed for its solution.
Part II treats of the definition of the noise figure of a fourterminal network and the most important methods available for itsmeasurement. An improved noise generator for the measurement of noisefigure is described.
