Cetabuoys and Hydrophones

From 2003-2012 we transmitted live humpback whale songs to our website via moored buoys and a radio repeater system. We then migrated our broadcasting to Wave Glider® based cell data systems. Our buoys were called Cetabuoys named after Cetacea, the order of marine mammals which includes whales, dolphins and porpoise. The equipment of the CetaBuoy project could be broken down into six major components:

1. The CetaBuoys and Hydrophones
2. Buoy Electronics
3. The Radio Repeater System
4. The Shore Controller and other interface tools
5. The Software for Web Interface
6. Rigging and Location

The CetaBuoys (or "buoys" for short) were 10 feet tall and 4 inches wide, with an outer shell of thick ABS plastic.

The outer layer of the buoy had a foil, or "wing" which provided a dramatic reduction in drag from the water. The wing was foam-filled for additional buoyancy, and had a solar panel on the area above water (the upper 3-4 feet), for battery support and additional power.

The solar panel on the buoy allowed it to remain in the water for the entire season without needing to be pulled for battery recharging.

The radio, batteries, and electronics package were housed within the inner casing, with ballast at the bottom for stability. This inner casing was designed to be slid into the CetaBuoy intact, and could easily be removed for repairs, diagnostics, or enhancements to the electronics.

The CetaBuoy was designed to float upright with approximately 2 feet out of the water and 8 feet underwater. The "wing" or wedge on the outer casing was foam-filled for buoyancy, and designed to reduce drag in strong ocean currents, while minimizing kelp entanglement.

Buoy Electronics

The heart of our entire system was our Control Board - known as the JEM5. (Jupiter Electronics Module - 5th generation)

The GPS (global positioning system) receiving antenna and UHF (ultra-high frequency) transceiving antenna were located at the top of the "sled" (the inner casing of the buoy) and connected to the JEM5.

The JEM5 transmitted the GPS and UHF communications to the Shore Controller, and received commands from the Shore Controller as well as Handheld Controllers. This was how the whales' sound, as well as, other data were transmitted.

Communications with JEM5 could be also used to:

• Set transmit durations
• Choose when to transmit
• Receive and sends telemetry information to & from shore
• Control solar charging of batteries

There were also six batteries (12 volts of power) recharged by the onboard solar panel These could also be charged through the hydrophone connector so that the batteries could be kept at full capacity while in storage.

The radio repeater system

The Radio Repeater System was at the Kahua Ranch on the western slope of the Kohala mountains, and provided bi-directional repeating of the radio signal.

When the buoy transmitted, the radio on the mountain heard it and simultaneously retransmitted it on another frequency. The faint signal coming from the buoy was amplified by the repeater to the Shore Control.

Conversely, when the Shore Control System transmitted commands to the buoys they were picked up by the Repeater and simultaneously retransmitted to the buoys. The Repeater transmitted on different channels for the different buoys.

The Repeater System allowed us to cover a very wide area (40-50 miles) for listening to the whales. Before installing the system we had about 1-2 miles of coverage.

When the whales sang (or made feeding or other calls) the sound was picked up by our hydrophone and transmitted by our CetaBuoy.

The signal was then picked up by the radio tower at Kahua Ranch and relayed to our server. The server, using satellite communications or direct internet links, broadcasted the sounds onto the internet.

The historic Kahua Ranch graciously allowed us to install a radio system on their grounds, 3800 feet above sea level.

The shore control system

The Shore Control System, then housed in our laboratory facilities, consisted of a computer connected directly to the internet, and connected to a control box which was connected to the Radio Repeater.

The computer ran software that, when commanded through the web, told a control box what commands to send to the radio or through the radio to the buoys. This allowed remote control of the system from anywhere in the world that we had internet access.

There was a small computer network radio transceiver connected to an antenna mounted on the roof of our lab which sent transmissions to and from the Repeater. If the Repeater failed, this transceiver could work as a backup, but only to a maximum 2 mile radius.

We used a small (handheld) hardware control system which translated commands from the computer so they controlled the radio receiver.

Software for Web Interface

We had a small web-server in our lab which provided a buoy administration page. This was our web-interface. We could send different commands (or queries) to all buoys at once, or to a specific buoy, such as:

• Start transmitting now
• Your transmit time should be x minutes long
• What is your GPS latitude/longitude?
• What is the water temperature?
• Hydrophone gain could also be controlled to adjust to the distance the whales were from the buoys.

We automated some of the features (a sort of "autopilot"). Some examples of autopilot functions:

• Keep track of battery voltage as reported by each buoy
• If voltage gets too low, the buoy would be put into standby mode so that it could charge its battery
• When voltage was high enough, the buoy could be reactivated

Rigging and Location