Woon Hyun Cho
Acoust. Simulation Lab., Naval R&D Ctr., Jinhae P. O. Box 18, Kyungnam, Korea
A new algorithm is developed for estimating the delay times and spectra in mixed wave fields. The algorithm is applicable to a spatial and temporal data window in which more than two events are present. In implementing the method it is assumed that data are recorded at equispaced hydrophones located in a spatial window in which the delay times are constant. Application of a least-squares criterion reduces the mathematics to an eigenvalue problem. The eigenvalues are complex, and their magnitude determines the frequency-dependent SNR. The phase is a linear function of frequency with a slope that determines the delay time over unit hydrophone spacing. The input data consist of the cross-power spectra between subarrays that contain the same numbers of elements and are shifted by zero or one hydrophone separation. Examples illustrate the application of the algorithm to synthetic data.
Standards Committee S12 on Noise. Working group chairs will report on their progress for the production of noise standards. The interaction with ISO/TC 43/SC1 and ISO/TC 94/SC12 activities will also be discussed, with reference to the international standards under preparation. The Chair of the respective U.S. Technical Advisory Groups (H. E. von Gierke) will report on current activities of these International Technical Subcommittees under ISO and preparation for the next meeting of ISO/TC 43/SC1, scheduled to take place in Oslo, Norway from 31 May to 4 June 1993.