Frequency Characteristics Extraction of Infected Wheat BPE Signals Based on Bispectrum Analysis and High-Order Spectrum Distribution

Spontaneous biophoton emission (BPE) signals of wheat have strong nonlinear and non-Gaussian, the traditional time-frequency analysis method cannot effectively analyze the spontaneous BPE signals of wheat. This study uses the bispectral analysis technique to process BPE signals for the first time and extracts the high-order spectrum distribution characteristics of normal wheat and infected wheat. By estimating the bispectrum, the slice bispectrum, and the characteristic parameters of the diagonal slice spectrum and the horizontal slice spectrum, the bispectral distribution characteristics of the spontaneous BPE signal of normal wheat and wheat that has been infected by insects are obtained. Bispectral analysis can not only eliminate the interference of Gaussian noise, but also elucidate the amplitude and phase information of the signal. Experiments show that the extracted parameters of the BPE signals yield a detailed spectral distribution and show differences between infected wheat and normal wheat. The results of this study provide a comprehensive description of the characteristics of infected wheat and provide an experimental and theoretical basis for the detection of insects in grain.