LORA: A Model for Predicting the Performance of Long-Range Active Sonar Systems.

摘要

LORA is a model developed to predict the performance of long-range active sonar systems. The supporting computer program uses 3-8 cpu seconds per run on the UNIVAC 1110 computer and requires 38,000 words of core storage. The performance prediction model comprises models that estimate propagation loss, reverberation level, and probability of detection. The propagation loss models are (1) empirical equations (modified AMOS) for near-surface ducts and (2) ray theory (Pedersen and Gordon) for direct-path, bottom-bounce, and convergence-zone sound propagation. The sound-speed profile is corrected for earth curvature, but is otherwise constant with range. Models for estimating reverberation use ray tracing to the centers of backscattering areas and volumes. The surface backscattering strength is obtained by using the Chapman-Harris equations, Eckart's equations, and Richter's data. The bottom backscattering strength uses equations derived from Lambert's Law and Schmidt's data. The volume backscattering strength is represented as column backscattering strength. Five probability-of-detection models are derived for various assumptions for signal distortion and detector characteristics. LORA features target doppler corrections for reverberation levels; multi-ping reverberation calculations; optional passive coherent and incoherent propagation loss outputs; and multiple bottom-bounce and multiple convergence-zone calculations. (Author)