Technology designed, built and tested a custom, high frequency
data collection system to support acoustic research in shallow
waters. Three acoustic nodes were deployed several thousand
feet apart in a shallow bay. Each node contained a 3-channel,
22kHz acoustic array, sound source and power amplifier. The
nodes were cabled to a central Data Acquisition Unit (DAU),
which digitized the node data and transmitted it to a Surface
Telemetry Buoy (STB). The STB radioed the data (10Mb/sec.) in
real time to a nearby site for display, processing and recording.
in-water system was remotely-controlled by radio from the receive
site. Commands were used to turn the system on and off, set
gains, actuate self-test modes and control the sound sources.
The sound sources could be commanded to output one of several
different waveforms (stored in DAU memory), at a selected amplitude.
Because the outgoing waveforms were synchronized precisely to
the DAU data frame, accurate time-of-flight measurements could
DAU could also interface to 32 low-bandwidth, non-acoustic type
sensors (pressure, temperature, environmental, etc.) using a
general-purpose sensor port on the DAU housing. The non-acoustic
signals were digitized and merged with the 10Mbit node telemetry.