Like the idea downloading the contents of a DVD in less then 10 seconds without a cable in sight? That’s exactly what a team of German engineers can do, having broken the record for wireless data transmission using terrestrial radio signals.
The team prepares its transmitter. (Image: Photo Jörg Eisenbeis, KIT)
A team of researchers from the Fraunhofer Institute for Applied Solid State Physics claims to have beaten the previous record for beaming data in this way by a factor of 10. To achieve the feat, they transmitted data on signals in the 71 to 76 GHz radio frequency band — which is usually used for terrestrial and satellite broadcasting.
But to squeeze in that amount of data requires an impressive signal-to-noise ratio, to avoid having to waste bandwidth on error-correction. So the team built a system of ultra-efficient transmitters and receivers. The transmitters are based on semiconductor chips made gallium-nitride, which provide a high-power signal that’s transmitted from a focussed parabolic antenna.
The team beamed the signals between a 45-storey tower in central Cologne and the Space Observation Radar in Wachtberg, 37km away. At the receiver, the researchers used special low-noise amplifiers built using indium-gallium-arsenide transistors. Their sensitivity allows them to detect incredibly weak signals.
The resulting speed of six gigabits per second has pretty obvious application. The researchers points out that a single transmission beam could be used to supply as many as 250 internet connections running at 24 meagabits per second to sites where it’s impossible to run a wired connection. While you might immediately think such a system would be best suited to, say, disaster zones, the researchers reckon it could even prove a “cost-effective replacement for deployment of optical fibre”. Watch this space.