Geeks in Oxford, England, have squeezed 13Mbps down and 3Mbps up a single channel of White Space – unused TV frequencies in their area – and used the tech to connect up river flood sensors.
The radio network – set up by bods at UK domain registry Nominet – is one a series of trials across Blighty using the gaps in telly spectrum to relay data: in this case, Nominet teamed up with LoveHz to test water-level sensors set up along the River Thames.
There is a big advantage to using this approach over cellular networks or ADSL: coverage and simplicity. Data sent over TV White Space (TVWS) doesn't require line-of-sight and the signal can travel for more than 8km.
LoveHz was able to develop simple, low-cost sensors in place of more complex and expensive ones used by the Environment Agency. The gear can be used to raise an early warning of rising flood waters.
The team also shared some of the lessons they'd learned so far. "Line-of-sight between stations is not essential," they noted, "but the best channel to operate on has to be carefully selected amongst the ones which actually present the lowest noise on both radio locations... In practice unexpected transmissions or high noise floor can make signal reception impossible."
Nominet is one of eight companies in the UK that is developing a White Space Database (WSDB) aimed at mapping the best frequencies available in every location in the UK (a similar map already exists for the United States).
It concluded that there is "the need for sensing technologies in both radios, such that a hybrid solution combining database and sensing can provide the optimal operational performance."
Other trials taking place across the UK – including one by Google and London Zoo that hopes to produce anti-poacher cameras for Kenya – have also helped regulator Ofcom assess the risk of interference between networks, the use of White Space wireless mics in stage performance, and double-check a plan – announced last week – to auction off the freed-up TV spectrum to mobile phone companies.
As an initial assessment by Ofcom concluded [PDF] that it was possible to run projects such as the Nominet/LoveHz Oxford flood system and a live performance of Les Miserables at the same time with no noticeable impact.
Other trials [PDF] including sending data to and from ferries, and running digital signage i.e. huge billboards.
While it is still early days, the first signs are that the use of this technology and spectrum could provide simple and low-cost networks that would help with the rollout of the so-called "internet of things".
If you want to know more about the tech, check out our story from back in 2012 on White Space networking. ®