A VAX-11/750 based ocean acoustic data acquisition and processing system for shipboard and laboratory use

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A VAX-11/750 based ocean acoustic data acquisition and processing system for shipboard and laboratory use

Decina, B.A. / Padgett, J.S.

An ocean acoustic data acquisition and processing system, based on a DEC VAX-11/750 minicomputer, was developed for both at-sea experiments and laboratory work. The system consists of the minicomputer, an array processor, a color display, an A/D converter and a high density digital recorder (HDDR). Approximately 50 hydrophone channels are digitized at a rate of roughly 1 kilohertz per channel and stored on the HDDR for immediate processing (at-sea) and/or postprocessing (lab). The data/signal processing tasks are to: 1) read and demultiplex HDDR data, 2) compute and store selected time-to-frequency FFT bins, cross-spectral matrices and FFT beamformer outputs, 3) plot hydrophone power, vs. time, 4) plot signal power vs. frequency and azimuth, 5) back up processed data and 6) maintain computer-generated logs describing the status of the data processing. Three features of the acquisition system are that it: 1) runs in continuous real time, 2) periodically transfers data files from disk to 9-track tape and 3) keeps a log of such files which allow ready monitoring and data retrieval for display and postprocessing. In addition, other program development and execution can run concurrently with the data acquisition and processing functions, all of which operate under the standard DEC operating system.