时空相关测速方法理论模型研究

Study of the theory model for temporal and spatial correlation velocity measurement

相关测速声呐与多普勒测速声呐相比有很多优点.相关声呐与常规测深仪相似,用单波束垂直向海底发射,回波比多普勒声呐的回波强,而且波束可以很宽,相同大小的发射换能器,可以使用低频发射.早期的声相关计程仪,多采用时间或空间相关法,用常规的相关解算装置确定速度.为提高测速精度,提出了基于声传播机理构造海底回波的理论时空相关函数的方法,该方法通过采集的回波数据构造数据相关函数,利用最大似然等方法估计未知参数.为测出舰船相对于地的绝对速度,较详细地推导了海底回波的时空相关理论函数,从而可利用最大似然方法估计船速.

The acoustic correlation log has striking advantages compared with the Doppler log. As with a conventional echo sounder, it uses a single beam pointing directly down at the seabed and the strength of return signal is much larger than that from a Doppler log because of the normal incidence. Furthermore the beam can be fairly broad, so that for the same size of transmission transducer, it enables the use of lower frequencies with less attenuation.Here model of temporal or spatial correlation was used and the velocity was determined by the general calculation set in previous correlation logs. The temporal and spatial correlation function in theory was proposed in order to improve the estimation accuracy, which is based on the principle of sound propagation from the echo in seabed. Data correlation function was obtained by echo collection. The unknown parameter was estimated by the method of maximum likelihood and other methods. Details of the proof are given regarding the temporal and spatial correlation function from the echo in seabed, allowing the ship velocity to be estimated using the maximum likelihood method.