达芬振子激励分叉在多普勒频移检测中的应用

以达芬(Duffing)振子模型在单频外激励下的分叉原理为基础,提出一种可在强噪声背景下检测微弱水声探测信号多普勒频移的新方法。当达芬振子的激励振幅超过某一临界参数时系统由混沌状态突变为周期状态。根据这一原理,首先在无噪声条件下确定达芬振子由混沌状态向周期振荡转变的分叉参数阈值,然后根据噪声强度适当调节分叉参数,使得系统输出稳定在单一周期状态。当噪声中含有微弱的多普勒回波时,通过理论分析可知系统输出为阵发混沌状态,且可根据混沌状态的间隔周期较准确地求出回波信号的多普勒频移。

Detection of Doppler shift based on excitation bifurcation of duffing oscillator

Based on the bifurcation principle of Duffing oscillators excited by single frequency signals,a new method for detecting Doppler shift of faint sound signals in a strong noise back-ground is introduced.When the amplitude of input signals in Duffing oscillators exceeds a certain critical value,the chaotic state of the system becomes periodical.According to this principle,the parameter threshold of the bifurcation without noise in Duffing oscillators is determined,and the parameter is then adjusted according to the noise intensity to make the periodical output steady.When there is faint Doppler echo in noise,the system output is intermittent chaotic,and the Doppler shift can be obtained accurately by calculating the interval of chaotic state.