OVAL has mounted a Pelco Spectra video camera where it can observe the
Haro Strait. The camera is controlled by a RS422 protocol that conveys
the location of an underwater sound source from the computer to the camera
within ~1/2 second of the occurence of a localizable sound. The camera
can turn from north to south in less than a half a second. The computer
also puts the localization position on the video display so that observers
of the video know what direction the camera is pointing.
Here are a couple of sample videos:
The video camera followed this container ship for about
20 minutes as it sailed north in the Haro Strait. To localize a sound
source, the sound must have short-term amplitude or frequency modulations
that allow time delays to be determined by crosscorrelation.
On this passby the orcas (J-pod) were travelling north.
You see a typical scene with whale-watch boats standing offshore. In this
short scene the vocalizing orca is underwater in the center of the scene
and then porpoises northward as the camera moves as successive calls are
localized in real-time (~ a second delay between vocalization and camera
repositioning). During this passby the orcas did not spy hop or breach.
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