It’s not every day your technology is used to achieve a world first. With our BlueComm underwater free-space optical modem, we’ve now achieved three world firsts in the past month.
The latest was the first official speech broadcast from underwater by the President of the Seychelles, Danny Faure, using BlueComms to transmit the video from inside a one of ocean science research organisation Nekton’s two manned submersible through water up to a vessel, from where it was broadcast worldwide, live.
His speech (available to view here), made from 121 meters below the surface, on Sunday (April 14), off the coast of Desroches, in the outer islands of Seychelles, was used to make a global plea for stronger protection of the oceans. The plea was made during a visit to Nekton’s First Descent mission, which is gathering data about some of the least explored area of the ocean offshore the Seychelles, in the Indian Ocean. The mission has also achieved to other firsts. On March 13, the world first broadcast of video to live audiences across the world from an untethered manned submersible by Associated Press. You can read more about that here.
The following week, Sky News presenter Anna Botting presented the world’s first live news bulletin from inside a manned submersible, some 135 metres deep. Co-presenter Martin Austin then broadcast from 250 metres deep in the twilight, or aphotic, zone of the little explored Aldabra Atoll, the following day, and described the experience – which included being in waters no one else had ever explored – as “extraordinary”.
Being able to broadcast to the world from the some of the world’s least explored areas of ocean, without wires, has been a dream of Nekton Mission Director Oliver Steeds. These broadcasts, which were also used to enable school children across the world to link live with the presenters in the submersibles, are helping to raise awareness of areas like the protected Aldabra Atoll, which Steeds likens to the Galapagos and Faure called the “beating heart of our blue planet.”
But, how exactly is the Nekton mission able to transmit video and audio signals through water?
They’re using our BlueComm through-water wireless optical modem. It uses high power light emitting diodes (LEDs) that are rapidly modulated to transmit up to 10 Mbps of data – that’s video quality and something that can’t be achieved with acoustics, which are traditionally used for underwater communications.
Water absorbs light, which is why, in the aphotic zone, from about 200 metres deep, very little light gets through. But, to us, the oceans appear blue, as this is the least absorbed colour of the light spectrum. This means blue a good colour for transmitting signals. In some waters, eg. shallower greener water, green is least absorbed, so green light is better to use.
Typically, BlueComm operates in the 450nm blue light region of the spectrum. Depending on the type of BlueComm, these signals are received either by photodiodes (BlueComm 100) or a photomultiplier tube (BlueComm 200), which is more sensitive, allowing communication ranges of up to 150 metres.
In shallow waters, where there is ambient light, we also have BlueComm 200 UV. It’s similar to the BlueComm 200, but operates at a shorter wavelength in the UV spectrum and with receiver filtering it, so it has higher tolerance to visible light, such as the subsea vehicle’s own lights or ambient light.
On Nekton’s First Decent mission, BlueComm 200s are being used. For this mission, Nekton wanted to transmit from both of its two submersibles at the same time. This is not an easy feat to achieve. For a start, it’s like trying to direct a ballet in the water. You have many things down there; ROVs (on a tether), the two submersibles, the depressor (BlueComm receiver). They all need to be within a small area, while making sure the ROV and depressor cables do not get tangled and also making sure that the vehicle lighting – which is crucial to actually being able to see what’s down there – doesn’t degrade the BlueComm signal.
You want good light for the submersibles’ cameras, but the BlueComms work best in low light, so there’s a balance to be met. Then, because there are two sets of signals, we needed to make sure the signals from our two BlueComm pairs didn’t interfere with each other. That’s why we’re using green and UV light BlueComms (one of each on each submersible), so that they could both be picked up without getting mixed up.
It’s clever and complex technology and, thanks to it, we’re helping to bring access to some of the least explored areas of the world’s oceans into homes around the world, via Nekton and President Faure. In turn, it is hoped that Nekton’s First Descent mission will aid greater understanding and awareness of the Indian Ocean and all our oceans worldwide. As Oliver put it: “We need to know how the oceans are changing especially the Indian Ocean, one of the least explored. We need to inspire people in different ways and pictures like this can do that and that means politicians can be given a mandate to act.”