The paper presents the results of the classical theory of fluctuations in the quasiharmonic van der Pol oscillator. Stochastic equations for amplitude and phase of selfsustained oscillations are formulated and then their solutions are analyzed. The autocorrelation function and power spectrum of noisy selfsustained oscillations are studied. Then the spectral and correlations characteristics of chaotic selfsustained oscillations are numerically analyzed in spiral chaos oscillators.
