RAOS, or Real-Time Acoustic Observing System, is an exciting technology being used in a new project that has recently gotten off the ground in our Acoustics Group.
With RAOS, we can simultaneously record under ocean sounds in a data base and send near-real-time specific messages or small snippets of data to land. This is a big deal! The current goal is to deploy RAOS technology in the Juan de Fuca Strait (the water way between Washington State and Canada near the San Juan Islands) to report on the movement of Orcas in real time. With only short (approximately 15 minute) satellite delays, scientists could be alerted on land that orcas have been detected in the area, so that a ship could rush out for immediate further study. The data base that comes back to land later, can be analyzed for larger-scale patterns of movement and species detection.
Brad Hanson (NOAA) and Holger Klinck kicked it off, and Haru Matsumoto has been instrumental in overseeing all aspects of the current RAOS project, including cost, coordinating with our NOAA PMEL Seattle work associates, and overall project management.
Here is how Real-Time Acoustic Observing System technology works: an Ocean Bottom Hydrophone (OBH) (an under-ocean microphone system) is deployed at the bottom of the ocean.
A buoy floats above in the general vicinity of the OBH. The hydrophone records sounds under the ocean and retains the ongoing recording data, but when a certain pre-determined signal is detected during this recording, it sends a message to the buoy, which, in turn, sends that to scientists on land (with a short delay for satellite relay time). The buoy, in this case, is kind of like the middle-man between the actual recording and detecting going on in the OBH at the bottom of the ocean and the scientists in the lab on land.
Alex Turpin took the lead on software engineering for this latest use of RAOS. Haru, Alex, and Chris Jones from Embedded Ocean Systems (EOS) in Seattle, collaborated on the engineering. Chris developed the WISPR board (circuit board)
and programmed it, and Alex customized it for this particular project to detect orcas.
The exciting thing about the WISPR (Wideband Intelligent Sound Processor & Recorder) board, is that we can change the detection algorithm (that programming that is geared to detect a certain particular sound) on the fly from afar. Theoretically, you could leave the RAOS out and have it sending you real-time signals to land if it detects orcas, and then change your project and have it send real-time signals to land if it detects blue whales or earthquakes instead – all without having to retrieve the instruments (a costly endeavor) and haul them back to the lab for changing of the programming.
Any time you have a large project in mind that requires a new technology, you must test test test. First, Alex tested it in the lab. Then he tested it off a dock. And the latest test, which took place under about 60 meters of ocean off the Oregon coast, was the biggie.
Joe Haxel helped with the mooring in the latest round of testing, using his logistics and ocean engineering expertise. On Sept. 19th, the OBH was recovered after a 5 day test deployment. So far, the data looks clean. (Personal note: I found that using an automatic detector to try to capture orca calls on a data set (not associated with the current RAOS project) was a bit frustrating if your hydrophone is anywhere near a buoy with a chain. Chain jingle was remarkably similar to orca whistle, according to the detection parameters). Before the recovery of the equipment after the 5 day test off the Oregon Coast, our scientists sent out orca sounds from the recovery ship to see if the hydrophone would detect it as orca, and send that signal to land via the buoy. This was done at 4 different distances from the equipment by stopping the ship and lowering a speaker into the ocean to play orca sounds using a high-frequency pre-amplifier to make sure all parts of the orca signal were present. Results are currently being reviewed in the lab.
Work is now under way in our Acoustics group for further collaboration with Chris of EOS in Seattle to refine the WISPR board programming in a way that allows it to send a small snippet of a spectrogram to land when the detection of the orca is registered at the OBH. In this way, scientists back in the lab could verify that the signal sent to them was, indeed, an orca and not a false detection (for instance, just a buoy chain), by viewing the actual signal’s spectrogram and/or listening to it with programs here in the office.
Once the latest collaboration is done on the WISPR board and RAOS system, and after testing this in the lab, the next step in the project will be deployment in the Juan de Fuca Strait. Good luck to all involved – Go, Team! We’ll keep you posted…