Fast and self-consistent ASW performance prediction

Traditional assessment methods for ASW sonar performance involve the calculation of transmission loss (TL) vs range and the identification of intersections between TL and the appropriate figure of merit. However the figure of merit (FOM) includes an ambient noise term, which itself is a function of the same sonar and environmental parameters (frequency, array depth, water depth, sound speed profile and so on) as TL. This leads to inconsistencies if the FOM is not recalculated to take into account a change to (say) the bottom type used for the TL,prediction. These inconsistencies can lead to incorrect or misleading conclusions concerning optimum values for detection frequency and array depth. For reverberation-limited active sonar the problems are greater still because the FOM (which must include a reverberation term) is then a function of target range as well.