ARRAY GAIN FOR THE CASE OF HORIZONTAL NOISE.
NAVY UNDERWATER SOUND LAB NEW LONDON CONN
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Array gain computations based on spatial correlation measurements in the 200-400-cps band and the directionality of the noise field for center frequencies of 112 and 178 cps are obtained. Both sets of measurements indicate more noise from the horizontal direction than from overhead at low frequencies, whereas the opposite is true at the higher frequencies. The results derived from spatial correlation measurements are compared with theoretical values for a directional noise field and vertical receivers, and the influence of sea conditions on the gain is demonstrated. For all element spacings of the 8-element array and all sea conditions considered, the gain varied from a low of 5 db to a high of 12.5 db. For the case of uncorrelated noise, a value of 9 db is obtained for array gain from 10 log N, where N is the number of elements. The results based on directionality of the noise field are below those based on spatial correlation, and the same trend with increasing wind speed is observed. The data for this calculation were available only for the upper half-plane. Author