Edgetech USBL BROADBAND ACOUSTIC TRACKING SYSTEM, User Hardware Manual, Page: 21 / 102

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OVERVIEW
The EdgeTech Broadband Acoustic Tracking System (BATS) is an Ultra Short BaseLine (USBL) Underwater
Tracking/Navigation System. BATS measures and analyzes sound waves sent from an acoustic source that
is attached to a target. The signal is received by a hydrophone to determine target position relative to the
tracking ship. The hydrophone amplifies the received acoustic signals and sends them to the Transceiver
and then to the PC for further processing by TrackMan.
The BATS uses USBL, phased-array hydrophone containing sound transducing elements arranged at the
vertices of an equilateral triangle. Each element is spaced less than half a wavelength away from each of
the other elements in the array. When a sound wave impinges upon the array it strikes one element first,
then one of its neighbors, and finally the remaining element. The sound wave, as sensed by any element
in the array, appears out of phase with the wave as sensed by the other elements in the array. The phase
differences between the elements in the array provide the information required to calculate a three-
dimensional vector from the array to the sound source.
Three types of sound sources are used with the BATS: pingers, transponders and responders. The
hydrophone receives the acoustic pulse transmitted by the pinger and determines bearing and Depression
Angle. Transit time of the pulse is unknown due to the fact the pingers operate asynchronously. The BATS
receives the pulse but does not know when the pulse was sent. A transponder emits a sound pulse in
response to a specific acoustic interrogation pulse from the controller transmitter. A transponder is
interrogated by the interrogation ceramic inside of the Hydrophone. A pinger emits a sound pulse at a
predetermined frequency, repeated at a set interval.
A responder emits a sound pulse via a wire connecting the responder and the Transceiver or BATS. The
system now has timing information to calculate directly the slant range of the target, assuming the
average velocity of sound in the water column and the turnaround time of the transponder or responder
are known. A responder works the same way as a transponder except instead of the hydrophone
transmitting acoustically, the BATS generates a trigger which is sent down to the beacon.
BATS Applications
• Towfish tracking & target position
• Diver tracking
•
AUV/ROV tracking
• Underwater construction