| 摘要 |
The invention provides a sound source for use in underwater seismic testing, the source comprising a substantially linear array of a predetermined number of air guns of differing volumes. The spacing between the guns is determined by a "weighted centroid distribution", this being determined by selecting a predetermined mathematical window function which is positive at all points within the window and which approximates to the Fourier transform of a single square wave, the width of the window being selected to correspond to the desired length of the array, and then dividing the area under the curve into areas which are the same in number as the air guns, and the relative proportion between the areas under the curve being the same as the relative effective weights of the individual air guns in the array. The centroid of each such area is then determined, and the positioning of the air guns is proportional to the separation of the centroids measured on the x-axis of the function. The mathematical window function may be a Hanning or a sinc function, for example. The effective weights (i.e. the primary pressure amplitude responses) of the air guns preferably increase symmetr-ically from the ends of the array towards the mid-point thereof. |
