Nonstationary quiver spindle background sound analysis of airplane via Wigner-Ville and wavelet time-scale distribution

Abstract

Cockpit voice recorder (CVR) in aircraft black box records many cockpit voices, such as speaker voices, noises, special meaning background sounds. Cockpit voices’ complex- ity exacerbates analysis difficulty through traditional differenti- ating hearing methods. These methods’ key techniques puz- zles such as cockpit voices’ characteristics identification are not resolved. According to the shortage in cockpit voice hearing and analyses by traditional Fourier transformation(FT) single time/frequency and short time Fourier transformation (STFT) double energy, the new methods ,which can applied to analysis of no stationary cockpit background sound, is set up by means of introducing Wigner-Ville time-frequency and wavelet time-scale technology respectively into airplane cockpit voice analyses, as an example of quiver spindle background sound recorded by CVR. Compared with these methods, it is demon- strated that the spectrogram of both smooth pseudo Wigner-Ville distribution(SPWVD) and its time-frequency re- distribution features high time-frequency resolution, immunity of cross term interference; and that the resonate frequency and response time are obtained by time-scale analysis of discrete wavelet transformation(DWT) .