Nonlinear effects of noise in electronic clocks

A theoretical analysis is given of the effects of random noise in various types of electronic clocks. Leaving aside the amplitude noise problems, the study concentrates on "linewidth" problems and analyzes the difference between quartz clocks and quantum devices. It covers the following main points: choice of the best scheme for tube clocks; nonlinear theory of thermal noise; non-linear theory of flicker noise; immunity of Robinson\´s oscillator to flicker noise. The analysis gives some hope that tube quartz clocks may be built with as high a linewidth quality as atomic clocks.