ON THE INTERPRETATION OF EXPERIMENTAL METHODS FOR INVESTIGATING NONLINEAR-WAVE PHENOMENA

Bispectral investigations and amplitude correlation methods are discus sed with reference to a simple synthetic signal which can be analyzed theoretically in detail. It is argued that even simple models based on a linear superposition of pulses can give a nonvanishing bispectrum. On the other hand, for signals which by construction do have internal phase relations, a triple correlation may well be vanishing, as demons trated by specific examples. Using the same synthetic signal a recentl y proposed amplitude correlation technique might be analysed also. The analysis is supported by a Monte Carlo simulation based on the propos ed model. The simulation can have wider applications for analysing the reliability of statistical estimators for finite record length signal s.