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Hardware implementation of parametric algorithm for asynchronously gathered measurement data based on the FPGA technology

Janowski T., Szworski K., Zając R.

Hydroacoustics

2009

Vol. 12

83-90

The hydroacoustic system based on DOA estimation utilizes passive antenna composed of many hydrophones. The samples of the arriving acoustic signal must be gathered synchronously from each hydrophone. This enables to take advantage of parametric processing signals methods. These methods make possible determination of the amplitude and the phase relationship among particular hydrophones. The newest complex systems made up of many sub modules uses network solutions. In the case of Ethernet network some standards (e.g. Precision Time Protocol) are defined to enable synchronization of the data (samples) gathered from many hydrophones by the clock synchronization. When the antenna consists of few hydrophones then the special concentrator connected point-to-point to hydrophones can be utilized. This article discusses the issue related to PTP as well as concentrator based on FPGA technology, which uses simple UDP protocol. In the case of concentrator the synchronous method of the I/Q detection which not requires synchronous samples acquisition is also presented.

High accuracy hydroacoustic system to study codend model parameters

Marszal J., Schmidt J., Jedel A., Schmidt A., Wojan Z., Zachariasz K., Leśniak W.

Hydroacoustics

2008

Vol. 11

271-278

An important task of fishing gear designers is to develop effective selective fishing gears by optimizing its geometry. The high accuracy hydroacoustic system for codend geometry measurements was designed for developing the construction of cod codend for the Baltic fishery. The system consists of 10 pairs of hydrophones, measuring microprocessor device and notebook computer. The high frequency short pulse excitation combined with the matched digital filtering make it possible to obtain high resolution of measure data. Additionally the thermistors mounted in the hydrophones are used to calculate the local sound velocity and enable precision calibration of obtained measuring data. The construction solutions, the measuring procedure and examples of obtained data are presented below.