| In this paper, a closed chamber technique for measuring the complex free field sensitivity and directivity patterns of line array is described. Projectors and monitoring hydrophones are placed n a chamber along its length. The projectors are driven By the required drives that are calculated aceording to a measured transfer matrix, and amplitude, frequency and incident of the predicted plane wave. Then the acoustic pressure field distribution which is equivalent to the predicted plane wave of any incidence is set up in the chamber. A prototype calilbration system has been developed. The system can operate over the frequency range from 20 to 600 Hz. The measurement results obtained in the chamber have shown in a good agreement with the theoretical predicted curves. |
