激光引信远距离定距目标回波微弱、信噪比低,针对传统脉冲式激光测距方式探测困难且测量误差大的难题,提出了基于互相关时延估计的数字化激光引信远距离定距方法.该方法首先通过快速傅里叶变换将发射脉冲和回波脉冲由时域变换到频域,然后对发射脉冲串序列的傅里叶系数进行共轭运算,并与回波脉冲串序列的傅里叶系数相乘,最后通过快速傅里叶逆变换得到互相关函数,对互相关函数进行峰值检测得到回波时延,从而实现目标定距.实验结果表明:该方法可以在低信噪比下实现目标定距,有效增加了激光引信的定距距离,最大测量误差为0.35m,误差主要来源于回波脉冲的展宽.%In order to solve the problems that conventional pulsed laser fuze long-distance ranging system had difficulties to detect the targets over long distance and the detecting precision was very poor due to the extremely weak echo signal and low SNR,a digital pulsed laser fuze long-distance ranging method was proposed based on the principle of cross-correlation time delay estimatioa Firstly, the transmitted pulse and echo pulse were transformed into the frequency domain from the time domain by fast Fourier transform. Then, the Fourier coefficient of transmitted pulse train was conjugate operated and multiplied with the Fourier coefficient of echo pulse train. Finally, cross-correlation function was obtained through inverse fast Fourier transform, and the echo time delay and target distance was got by peak detecting. The experimental results showed that cross-correlation time delay estimation was able to discover the objects of low SNR and improved the maximum ranging distance of the laser fuze. The measuring error which attributed to echo pulse broadening was less than 0. 35 m.
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