NATO Undersea Research Centre, Viale San Bartolomeo 400, 19126 La Spezia, Italy.
J Acoust Soc Am. 2011 Sep;130(3):1282-6. doi: 10.1121/1.3623750.
In active sonar the target echo level is often estimated with a propagation model that adds all multipath arrivals. If the (post-correlator) transmitted pulse is short compared to the multipath time spread then there is effectively an extra loss (which may be substantial) since only a few of the paths contribute to the target echo at any one instant. This well known "time-smearing" loss is treated in a self-consistent manner with previous calculations of reverberation [Harrison, J. Acoust. Soc. Am. 114, 2744-2756 (2003)] to estimate the target response and the signal-to-reverberation-ratio. Again isovelocity water, Lambert's law, and reflection loss proportional to angle are assumed. In this important short pulse regime the target response becomes independent of boundary reflection properties but proportional to transmitted pulse length. Thus the signal-to-reverberation-ratio becomes independent of pulse length. The effect on signal-to-ambient-noise is also investigated and the resulting formulas presented in a table.
在主动声纳中，目标回波电平通常使用传播模型进行估计，该模型会添加所有多径到达。如果（相关器后）发射脉冲相对于多径时间扩展较短，则会有效损失额外的能量（这可能是相当大的），因为在任何给定时刻只有少数路径对目标回波有贡献。这种众所周知的“时间模糊”损失与之前的混响计算[Harrison，J. Acoust. Soc. Am. 114，2744-2756（2003）]以一致的方式进行处理，以估计目标响应和信号与混响比。同样假设等速水、朗伯定律和与角度成比例的反射损耗。在这种重要的短脉冲情况下，目标响应与边界反射特性无关，但与发射脉冲长度成正比。因此，信号与混响比与脉冲长度无关。还研究了对信号与环境噪声的影响，并将得到的公式列在一个表中。
