XMax in pictures
Published: 04 Nov 2005 12:30 GMT
In a field in the Florida Everglades, the future of wireless broadband may be taking shape.
A company called XG Technology LLC is developing xMax, a wireless technology that offers the promise of high-speeds over long distances using very low power.
xMax uses licensed and unlicensed spectrum, and XG claims it can be deployed at a fraction of the cost of mobile WiMax and 3G.
The claims are jaw-dropping, but does the evidence stack up?
We've been to the Everglades to take a look. Here's what we saw.
A TV tower in Florida holds a prototype xMax transmitter producing five hundredths of a watt at 900MHz and transmitting digital data fast enough to carry a digital TV picture. Also at the site, analogue TV transmitters are using a million times as much power to do much the same job – technology has come a long way in more than half a century.
At the edge of the Everglades, a very temporary receiving station has been set up under an awning. The antenna is around twenty feet up and about the size of a small paperback book – although it has line of sight to the transmitter, something XG says will not be necessary when xMax is commercialised, no other wireless technology could attempt the demonstration that's under way.
The large box at the bottom of the picture is an oscilloscope set up to display the raw data received by the smaller box at the top. That smaller box contains XG's crown jewels, the still-secret receiver that can distinguish xMax's very weak signals from among a welter of much stronger transmissions – and do it well enough to provide broadband over exceptional distances and low powers. We weren't allowed to see inside, although the engineer did exclusively reveal the contents to be "another box — this one's just to look pretty for the demonstration".
xMax works! This is the first public evidence that the xMax system can deliver. On the screen of the oscilloscope is baseband data picked up by the prototype receiver; it is a stable stream of bits at a rate of around 4 Mbps. The GPS receiver to the right is independent confirmation that the distance to the transmitter is 18 miles: we were unable to check the details of that transmitter as it was some 800 feet above ground level. ZDNet UK saw that the bitstream vanished when the receiving antenna was moved out of alignment with the distant transmitter, when the engineer in the tower was told to turn the transmitter off by mobile phone, and when we removed the coaxial connector.
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