Internet of Things (IoT) technologies have made it possible to collect all sorts of data from all over the globe. This has been a huge boon to researchers studying the environment, agriculture, human health, and beyond. But the IoT revolution has yet to hit the world’s oceans, despite the fact that they make up over 70 percent of the Earth’s surface. Only about five percent of the ocean has been explored, so the mysteries contained in the other 95 percent will remain unknown until suitable means of exploring them are developed.
One of the biggest roadblocks standing in the way of oceanic exploration is communication. Traditional methods of communication that use some form of electromagnetic medium, like radio waves or light, cannot travel far through water. The best option available today, imperfect as it may be, is the use of sound. These mechanical waves can travel through water much more effectively than other options, however, the equipment required for underwater acoustic communication is exceedingly expensive.
An acoustic modem alone, which is only one part of a full communications system, typically costs in the neighborhood of $10,000. Quite a bit more than an ESP32 or a development board with a LoRa transceiver, right? Accordingly, this expense prices nearly everyone out of the game when it comes to deploying a large IoT sensor network underwater.
Testing the modem in the field (📷: University of Padova)
But progress marches on, and this problem may soon become a thing of the past. Researchers at the University of Padova have recently developed an acoustic modem, which they are selling through their startup, SubSeaPulse SRL. Called the Subsea Modem, the device only costs about one-tenth of what other modems on the market cost. They are also working on a transducer to pair with it, which is an antenna that converts between electrical and acoustic signals, that costs about 20 percent of what existing technologies do.
A key factor in the team’s ability to cut the cost so dramatically was the use of a Raspberry Pi single-board computer in the modem. A sound card HAT was attached to the Raspberry Pi, which allows it to both generate and record audio signals. When the software required for operating the device is loaded, the result is a software-defined acoustic modem that allows users to alter the signal modulation exactly as they want to support their particular application.
The Subsea Modem has the potential to put effective underwater communication technologies in the hands of many more researchers and device developers. That could have important implications for our understanding of the oceans and beyond. However, acoustic communication itself has a number of issues with distortion and limited range. Before we can truly have a worldwide, undersea IoT network, better communication systems will still need to be developed.
