Aquatic robots are busier than ever. They have seabeds to mine, cable pathways to plough, and marine data to gather. But they and their aquatic brethrenincluding submarines and scuba diversstill struggle to communicate. <\/p>\n
For decades, global standards defining Wi-Fi and cellular networks have allowed people to exchange data over the air. But those technologies are worthless below the waves, and no such standards have existed for underwater communications. <\/p>\n
Aquatic systems have instead used a mishmash of acoustic and optical signals to send and receive messages. However, manufacturers sell acoustic modems that operate at many different frequencies, which means those systems often cant speak to each other. <\/p>\n
We live in a time of wild west communications underwater, says Joo Alves, a principal scientist for NATO. <\/p>\n
Now, Alves and other NATO researchers have established the first international standard for underwater communications. Named JANUS, after the Roman god of gateways, it creates a common protocol for an acoustic signal with which underwater systems can connect. <\/p>\n
Acoustics has long been a popular medium for underwater communications. Generally, optical signals can deliver high data rates underwater at distances up to 100 meters, while sound waves cover much greater distances at lower data rates. <\/p>\n
The main role of JANUS is to bring todays acoustic systems into sync with one another. It does this in part by defining a common frequency11.5 kilohertzover which all systems can announce their presence. Once two systems make contact through JANUS, they may decide to switch to a different frequency or protocol that could deliver higher data rates or travel further. <\/p>\n
In this way, Alves compares JANUS to the English languagetwo visitors to a foreign country may speak English to one another before realizing they are both native Spanish speakers, and switch to their native tongue. <\/p>\n
Chiara Petrioli, a specialist in underwater sensors and embedded systems at La Sapienza, the University of Rome, says JANUS could be the first step toward an Internet of Underwater Things\"a submerged digital network of sensors and vessels. <\/p>\n
In addition to designating a frequency, JANUS also provides a modulation encoding scheme to describe how data should be encoded onto a sound wave, and describes the particular waveform that should be used (known as FH-BFSK). It also spells out which redundancies should be added to the data stream to minimize transmission errors. <\/p>\n
In order to use JANUS, a system would first emit three optional tones to indicate that it intends to broadcast a JANUS data packet hitched to a sound wave. Then, the system would pause for about 400 milliseconds to allow other devices in its vicinity to wake up. Next, the system would broadcast a fixed series of tones to ensure both systems were properly synchronized to the JANUS protocol. Finally, the system would send the JANUS packet, consisting of 56 bits followed by a redundancy check, which tests for transmission errors. <\/p>\n
The JANUS standard was developed by Alves team at NATOs Centre for Maritime Research and Experimentation in La Spezia, Italy and sponsored by NATOs Allied Command Transformation. It is the first underwater communications standard to be defined by an international body. <\/p>\n
Milica Stojanovic, an expert in oceanic engineering at Northeastern University, expects other standards will soon follow. She says the 11.5 kHz frequency used by JANUS is great for transmitting data between 1 and 10 kilometers, but a lower frequency, perhaps 1 kHz, would be better for sending data over longer distances of 10 to 100 km. <\/p>\n
Even with JANUS and other standards, any future underwater Internet will probably be cursed by far lower data rates than modern Wi-Fi or cellular networks. Sound travels at much lower frequencies, and on much longer waves, than the signals used for consumer electronics. Though sound waves travel faster in water than on land, they still travel more slowly through water than radio waves through air. <\/p>\n
To develop JANUS, Alves team relied on the Littoral Ocean Observatory Network, a collection of tripods that NATO researchers have placed on the seafloor in the harbour of La Spezia, Italy. Each tripod emits acoustic signals to other tripods, which send performance reports to researchers through undersea cables. Those reports helped the team understand how fluctuations in water temperature, and other environmental changes, will affect JANUS signals. <\/p>\n
The tripods also allowed researchers to build a JANUS receiver, advanced versions of which could minimize decoding errors and account for the Doppler effect. The Doppler effect describes shifts in sound waves caused by motion, such as the whirl of an ambulance siren as it drives by. <\/p>\n
In another series of tests, researchers aboard the research vessel Alliance, a NATO ship operated by the Italian Navy, measured the performance of JANUS signals along the surface of the ocean. <\/p>\n
Once deployed, aquatic systems could use JANUS to send data directly to each other, or to gateway buoys bobbing on the waters surface. The buoys could then use radio waves to relay that data to nearby control centers. <\/p>\n
In one demonstration, Alves group helped the Portuguese Navy set up a buoy that converted data about the positions and speeds of nearby ships to JANUS. The buoy rebroadcast this information to Portuguese submarines lurking below. <\/p>\n
Based on their work, Alves says submarines could also use JANUS to issue calls for help to ships and rescue crews. Using an open scheme like JANUS to issue distress calls would increase incredibly the chances of those being picked up, he says. <\/p>\n
Now that JANUS is available, manufacturers of aquatic systems must decide whether or not to adopt it. Alves is confident they will, and Petrioli, who contributed feedback to the development of JANUS, agrees that adoption is essential to the industrys future. <\/p>\n
But Stojanovic is not so sure. If there starts to develop a serious market, then everybody will have to play to the same tune, she says. If not, and everybody finds their own niche market with their own protocols, then they will do that. <\/p>\n
IEEE Spectrums general technology blog, featuring news, analysis, and opinions about engineering, consumer electronics, and technology and society, from the editorial staff and freelance contributors. <\/p>\n
Sign up for the Tech Alert newsletter and receive ground-breaking technology and science news from IEEE Spectrum every Thursday. <\/p>\n<\/p>\n
The new JANUS acoustic signal will connect aquatic robots and sensors into an Internet of Underwater Things 8Jul <\/p>\n
So far, harvesters can get milliwatts of electricity from sound. That might be enough for some things26Apr2011 <\/p>\n<\/p>\n
A prototype from the University of Washington leverages a backscattered radiofrequency wave to transmit analog signals 7Jul <\/p>\n<\/p>\n
As fictional geniuses in HBO's \"Silicon Valley\" seek to reinvent the Internet, Mozilla and the NSF offer $2 million in prizes to decentralize it in the real world 30Jun <\/p>\n<\/p>\n
Intel says its new Olympics sponsorship is about changing the experience for the digital generation 21Jun <\/p>\n<\/p>\n
With massive MIMO, future 5G networks will be able to cram more data onto the same amount of spectrum 17Jun <\/p>\n<\/p>\n
Instant photo sharing celebrates its 20th birthday today, proving that building a prototype when your wife is in labor is sometimes a good idea 11Jun <\/p>\n<\/p>\n
The Pied Piper of the TV show's fictional quest to reinvent the Internet trails the progress of MaidSafe and the University of Michigan 9Jun <\/p>\n<\/p>\n
Afghan Wireless has overcome many challenges in its efforts to bring wireless service to the country 1Jun <\/p>\n<\/p>\n
Startup Phazr has emerged from stealth mode and quickly become a darling of the wireless industry 23May <\/p>\n<\/p>\n
High-frequency millimeter waves will greatly increase wireless capacity and speeds for future 5G networks 6May <\/p>\n<\/p>\n
Proponents say the new LTE-based technology will be deployed like Wi-Fi in factories, hotels, and airports 1May <\/p>\n<\/p>\n
Were closer than ever before to the next generation of wireless, but expectations have cooled slightly 21Apr <\/p>\n<\/p>\n
Facebook's Yael Maguire talks about millimeter wave networks, Aquila, and flying tethered antennas at the F8 developer conference 19Apr <\/p>\n<\/p>\n
Full duplex could double the capacity of wireless networks, making it a key technology for 5G 1Apr <\/p>\n<\/p>\n
Just hold it in front of your face, and youre in 29Mar <\/p>\n<\/p>\n
University of Michigan researchers spoof an accelerometer by hitting the right note 17Mar <\/p>\n<\/p>\n
Instead of a dedicated antenna, the company's approach radiates radio-frequency signals from the ground plane 14Mar <\/p>\n<\/p>\n
Dont expect early 5G service in South Korea to reflect what carriers elsewhere have described 8Mar <\/p>\n<\/p>\n
The company knows it needs to ditch the dongle, and believes Li-Fi-enabled chipsets will be here soon 1Mar <\/p>\n
<\/p>\n
Read this article: Aquatic robots are busier than ever. Continue reading
\nNATO Unveils JANUS, First Standardized Acoustic Protocol for Undersea Systems - IEEE Spectrum<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"