Display of acoustic reflection profiles using a dot matrix plotter

• Published in: Ocean engineering 1976-01, Vol.3 (4), p.167,IN1,169-168,IN2,173
• Main Authors: Milligan, S.D., LeBlanc, L.R., Middleton, F.H.
• Format: Article
• Language: English
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/0029-8018(76)90021-4

Acoustic reflection profiling data display is traditionally done with the aid of a facsimile type of recorder. It is not uncommon to record the unprocessed acoustic data on a tape recorder for subsequent playback through a laboratory computer. This still involves the use of some sort of facsimile recorder for the ultimate display of profiles. This paper presents the results of a study to adapt a high-speed digital dot matrix plotter for the ultimate display in place of the conventional facsimile recorder. Because a minicomputer drives the display directly, a host of signal conditioning procedures are permitted, with the final display being generated in real time. Algorithms are developed to control the marking density, allow adaptive threshold control, bottom tracking, automatic gain control, and de-emphasis of water column boundary reverberation. These techniques are just a few of the many that can be employed since the computer can readily be carried on a large ship in deep water, or a small vessel in a harbour. Shallow water is the difficult case for high energy acoustic sources because the water column boundaries behave much like an excited acoustic cavity. For this reason, a section of seismic profile is shown which was obtained with a 7·5 kHz pinger in only 8 m of water in Narragansett Bay. This research was partiallysupported by the Division of Computer Research of the National Science Foundation.