抵消Wigner-Ville分布交叉项的窄带运动声源无源测速

Cross-term rejection in the Wigner-Ville distribution for velocity estimation of a narrowband sound source

利用声波的多普勒频移可以对窄带运动声源进行单传感器无源测速,其性能很大程度上取决于能否精确地估计出声波的瞬时频率.Wigner-Ville分布虽然时频分辨率高,但存在交叉项干扰,很少被直接用于瞬时频率估计。对此,提出了抵消Wigner-Ville分布交叉项的单传感器窄带声源无源测速方法。利用交叉项与声源速度的关系构造一个抵消项,引入到Wigner-Ville分布中,通过对声源速度估计值进行迭代更新,使抵消项与交叉项相位相反,从而约掉交叉项。经实测噪声数据验证,对一辆以6.07 m/s匀速运动的卡车(信噪比约为29 dB)测速误差为0.1 m/s,运行时间为4.6 s,对一架以28.90 m/s匀速运动的直升机(信噪比约为16 dB)测速误差为0.46 m/s,运行时间为1.2 s,均优于匹配Wigner变换和多普勒线性调频小波变换测速方法.

Doppler shift of the sound wave is widely used to passively estimate the velocity of the narrowband moving source by a single sensor.The performance largely depends on the instantaneous frequency estimation accuracy.The Wigner-Ville distribution provides a high-resolution tool in time-frequency analysis,but it is hardly used for instantaneous frequency estimation due to the existence of the cross-terms.To tackle this inconvenience,a method for cross-term rejection in the Wigner-Ville distribution is proposed to passively estimate the velocity of a narrowband sound source by using a single sensor.A rejection term is introduced to Wigner-Ville distribution,which is formulated based on the relation between the cross-term and the source velocity.The method updates the source velocity estimate iteratively,making the rejection term and the cross-term opposite in phase so as to cancel the cross-term.The experiment results show that the estimation error for a truck at the speed of 6.07 m/s(signal to noise ratio is approximately 29dB)is 0.1 m/s and the run time of the method is 4.6 s.Furthermore,the error for a helicopter at the speed of 28.90 m/s(signal to noise ratio is approximately 16 dB)is 0.46 m/s and the run time is 1.2 s.The performance of the proposed method is superior to matched Wigner transform and Doppler chirplet transform both in terms of the precision and the computational efficiency.