A PCM data acquisition system for nearshore

A system designed to give maximum flexibility and portability has been developed to collect wave, current, and other physical data within the dynamic environment from the surf zone to the edge of the shelf. The system consists of a radio-linked shore station housed in a mobile van and as many as six shelf stations mounted in bottom reference spars. Deployment of a shelf station can be accomplished using a small boat with minimum diver assistance. This ease of deployment coupled with the mobility of the receiving shore station allows field studies to be conducted at remote coastal sights. Each of the shelf stations is designed to accommodate as many as fifteen sensors. All simultaneous sensor outputs are digitized and transmitted, using pulse code modulation (PCM), to the mobile shore station, where the received signals are processed and selected for recording on strip charts or digital magnetic tapes for computer analysis. Very high sampling rates and an IRIG time code system are used to insure precise time correlation between all data channels, including those from separate shelf stations. A single shelf station would transmit data from an array of wave sensors, thus providing continuous wave climate including the two dimensional wave spectra. Some different combinations of shelf station ensembles are shown.