Research On The Statistical Model Of Target Strength Fluctuation Of Underwater Targets

Target strength is an important parameter to describe echocharacteristics of underwater targets and sensitive to azimuth angle.Because of random factors, such as working condition and movement,echo amplitude and experimental result of target strength are random andfluctuate. At present, target strength forecasting models, deterministicmodel, can’t represent target strength fluctuation and error will occurdefinitely. Therefore, it is necessary to develop an appropriate statisticalmodel of target strength fluctuation by analyzing statistically.Based on the highlight model of underwater targets，the cause oftarget strength fluctuation is clearly stated. Referring to radar cross sectionstatistical model, sonar cross section statistical model fitted to all kinds ofunderwater targets is developed and the statistical model (Ts distributionmodel) of target strength fluctuation is deduced, obtaining the statisticalparameter. The fundamental characteristics of Ts distribution model werestudied. On the one hand, Ts distribution model can directly represent themean target strength. On the other hand, Ts distribution model canrepresent target strength fluctuation.To primarily verify Ts distribution model, numerical result of targetstrength fluctuation of SSN simplified submarine, single hull Benchmarksubmarine and double hull Benchmark submarine is statistical analyzed.Then, the Ts distribution model is further verified by the experiment of scaled down underwater target models. The Ts distribution model agreedwell with the probability distribution function of target strength of differentunderwater targets at different frequencies. It can be concluded that Tsdistribution model can accurately describe the target strength fluctuation ofunderwater targets.