Bias Error in Acoustic Direction, Bearing Finding, Due to Reflections from211 Parallel Crest Sea Surface Waves, and Bias Error Compensation

摘要

In passive acoustic direction, bearing measurements, errors due to reflections211u001efrmt he sea surface, can occur both in terms of fluctuations and bias error, the 211u001elatter for parallel crest sea surface waves. The task is to relate bias error to 211u001eparameters for the sea surface waves, to frequency, and to position parameters 211u001efor the target and own vessel, the latter a submarine. By such a relation, 211u001ebearing bias error compensation can be obtained. A 3-dimensional treatment is 211u001eneeded for this. As preparation for this treatment, and for judgments on error 211u001evariations, a large amount of 2-dimensional treatment is needed. Types of, and 211u001eeffects of water particle movements on rays and Doppler shift and spread, of 211u001eregular and random sea surface wave ripple on strength of reflections, and for 211u001elow grazing angles, of acoustic shadow zones and air bubbles, are treated. 211u001eBearing bias error compensation, with acceptable belief, is within a fraction of 211u001e1 degree.