Author: Matthew Kingsland – Communications Application Engineer
Water is an incredibly hard medium to communicate through. In air we are all used to having almost unlimited data in our pockets and being able to stream the latest YouTube cat video at a moment’s notice. However go just a few metres underwater and all that stops. Water absorbs, attenuates and tempers just about any signal travelling through it. This means for many years, subsea wireless communication has been limited to speeds which make a dial-up connection look fast.
For years, the market has concentrated on subsea acoustics development because it was the only wireless technology available. Acoustics still provides the best operating range of any available technology, but at present the majority of deep water (3-4 km) acoustic modems are limited to around 5-10 kb/s while some short range shallow water offerings can go up to 100 kb/s. Progress is being made in improving acoustic solutions, but the possibility of a Mega bit per second (Mb/s) acoustic link is still very much in the conceptual stages.
The subsea market has learned to live with such limitations, either tethering equipment or reducing the data sets to the absolute minimum for acoustic transmission. However, as technology advances, alternatives to the acoustic pressure wave are becoming a reality.
Our preferred alternative is free space optical communications. While mathematical models show the maximum theoretical communication distance is limited to several hundred meters the possible data rates can be incredibly high, as shown by the current optical fibre speed record standing at over 1000 Gb/s.
With recent improvements in silicon technology, high power LED technology and advanced optical sensors, it was possible to see how wireless broadband speeds might come to the subsea world. This research led, 6 years ago, to Sonardyne investing in subsea free space optical communication. Since then, together with our partners Lumasys, we have been developing our optical communications range. The technology will never replace acoustics, but it will certainly complement it.
As with any technology, there are trade-offs during the design between different performance criteria, which is why we now have a range of BlueComms each designed around a different maximum performance characteristic:
- – BlueComm100 – Small & operates in all ambient light conditions for a consistent performance
- – BlueComm200 – The longest range performance for remote control & live video
- – BlueComm5000 – The highest data rate for the fastest possible wireless data collection
Keep an eye out for my next blog, as I take a look at the science behind BlueComm.
If you would like to find out more about our BlueComm, you can read more here, or if you would like to talk to us about how BlueComm could work for your next project, please get in touch.