Main Perth Thermometry Science People Engineering The Experiment Epilogue
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Engineering efforts for the HIFT experiment consisted of a number of components. The acoustic sources are specially designed for high power and low frequency. The ship used to conduct the experiment had to be robust enough to withstand the extreme weather of the Southern Ocean. A variety of hydrophone arrays, the acoustic receivers, were used to study the acoustical signals. Finally, extensive research on signal processing was conducted, both to craft an optimal collection of signals to transmit from the source and to optimally process the received signals to glean the most information possible from them.

The acoustic sources

HLF-4 acoustic sources was used to make the acoustic transmissions. In the course of the experiment, several of the acoustic sources were destroyed by the effects of foul weather!


The R/V Cory Chouest

The R/V Cory Chouest preparing to go to sea.

Arrays of hydrophones

Some of the hydrophone arrays were deployed from a ship (left), others were bottom mounted (right). These were arrays of many hydrophones that are used to resolve some of the spatial properties of the arriving signals.

The portable single hydrophone system

One of the interesting aspects of this experiment was a collection of cheap, portable receivers that were sent out to a variety of research groups around the world. This instrument was designed and built at the Applied Physics Laboratory at the University of Washington. APL hosted a few workshops or two for the participants from around the world to get familiar with the devices,

The device was a orange disk buoy about 2-3 ft diameter with electronics/antenna in center, and a hydrophone hanging down. The electronics were similar to a standard U.S. Navy sonobuoy. One goal with these devices was to get the hydrophone into the sound channel, so a much longer cable connecting hydrophone to the electronics was employed. This cable consisted of a coiled black cable with hair fairing.

A photo of one of these receivers in action in the Indian Ocean can be seen HERE.

Signal processing

Main Perth Thermometry Science People Engineering The Experiment Epilogue
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