| Abstract: | A single watergun generates a ‘stand-alone’ narrow pulse of acceptable energy content and broad-band spectrum. When multiple units of equal volume are fired simultaneously and are accurately synchronized, carefully depth-controlled and spaced beyond their near-field interactive distance, the energy measured in the far-field increases proportional to the square of the number of individual units employed. When these multiple units are configured in areal array designs based on distance weighting or varying density distribution of the equal elements, further gains in downward directivity and attenuation of horizontally traveling interference accrue. Such pattern designs take account of the spectral content of the particular watergun used, while the wavenumber response is concentrated to attenuate the dominant interference at water velocity. Finally, the high-frequency content, and high repeatability and synchronizing accuracy of the new generation of waterguns improves the high resolution potential to help combat natural earth absorption losses. We should, therefore, keep the ‘in-line’ dimensions at both source and receiver as short as possible. Unacceptable interference that persists during subsequent processing can be controlled by the long-array simulation technique. |
