基于线性调频(LFM)信号的单体鱼类目标回波识别与性能分析

Detection and performance analysis of single fish target echo by using LFM signal

在估计鱼类目标强度时,需要选择单体的回波信号进行计算。窄带信号下回波的相位标准差是单体检测的关键指标,但对于宽带信号相邻两点的相位差是时变的,无法将回波相位标准差作为单体信号的判定依据。本研究对线性调频宽带信号下的单体识别方法和性能进行了分析和仿真,并对该方法在消声水池内进行了测试和验证。结果显示:相比窄带信号,宽带信号的距离分辨能力与其带宽成正比,随着带宽提高,宽带信号探测的距离分辨率也相应提高,具有更好的单体目标识别性能;和单体信号回波相比,距离接近的多目标干涉回波,其回波内的短时角度变化显著增大,使用回波内角度标准差作为单体识别指标代替相位标准差能获得较好的识别性能。

In the estimation of fish target strength,it is necessary to select the single echo.The phase standard deviation of the echo in a narrowband signal is a key indicator of the single target detection,but the phase difference between two adjacent points of a wideband signal is time-varying,so can’t be used as the judgment basis of single.This study analyzes and simulates the performance of single target recognition under wideband signals,then tests and validates.The result shows that compared with narrowband signals,the range resolution of the wideband signal is directly proportional to its bandwidth.With the increase of bandwidth,the range resolution of wideband signal detection increases,and it has a better single target recognition performance.Compared with the single echo the short-term angle change in a multi-target interference echo with a close distance increases significantly.Using the standard deviation of the internal angle of the echo as the parameter instead of the phase standard deviation can also obtain good recognition performance.