Aircraft acoustic signal modeled as oscillatory almost-cyclostationary process

The acoustic almost-cyclostationary signal emitted by a moving aircraft is modeled as an oscillatory almost-cyclostationary process when it is received by a stationary listener. Its autocorrelation function is constituted by the superposition of angle-modulated sinewaves, where the angle modulation is consequence of the time-varying delay due to the relative motion between aircraft and listener. Conditions under which the source almost-cyclostationary signal can be recovered by the received signal by time de-warping are established. Thus, cyclic features of the source signal carrying information on aircraft parameters are estimated by classical cyclic spectral analysis.