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 This week, US company SkyTower, a subsidiary of AeroVironment, said it had successfully performed a series of tests in Hawaii of its new technology, a communications airplane called Pathfinder-Plus.
Working with NASA and the Japanese Ministry of Telecommunications, SkyTower said it had launched the plane, which climbed to 65,000 feet above Kauai, Hawaii, and transmitted several hours of 3G mobile voice, data and video service to the ground, where it was received on an NTT DoCoMo 3G handset. Data was transmitted at 384 kbps during the test.
Pathfinder-Plus, with its 121-foot wingspan, is no ordinary airplane. The vehicle is unmanned and runs on solar power, which means it needs to land at night. But the company claims that advances in battery technology could give the airplane the ability to stay airborne 24 hours a day, allowing it to fly for six months at a time. The airplane also has a tight turning radius, which in conjunction with low-cost, stationary user antennas, makes the plane appears geostationary from the ground.
"The airborne platform, operating above the weather and commercial air traffic, is equivalent to a 12-mile-tall tower, which means significant advantages to telecom service providers and broadcasters," said Stuart Hindle, vice president of strategy and business development, SkyTower.
Indeed telecoms in Europe and elsewhere have spent billions rolling out 2.5G and 3G platforms over the last few years, but SkyTower claims it could dramatically cut those costs. "Given the amount of money that wireless service providers have spent on spectrum licences for both fixed and mobile applications, these SkyTower tests should be of great interest," Hindle said. "Imagine launching a single platform, having instant metropolitan-wide market coverage, and eliminating the terrestrial costs associated with tower build-outs and backhaul."
During the test flight, the company also successfully tested digital high definition television broadcasts from its stratospheric transmitter. And the company pointed out that because of its much higher "look angle," SkyTower platforms can fill in "urban canyons," or areas currently missed by terrestrial and satellite broadcast transmissions due to tall buildings or terrain.
Furthermore, during the tests, a 24 mbps data rate was achieved using only 1 watt of power -- less than 1/10,000 the power used by a typical terrestrial broadcast transmitter that has to overcome buildings, trees and other obstructions to cover the same area.
With funding from the Japanese Ministry of Telecommunications, a consortium of Japanese manufacturers including NEC and Toshiba developed the communication systems carried by Pathfinder-Plus for the HDTV and IMT-2000 testing. Fuji Heavy Industries integrated the payloads for the company's flights.
Interestingly, telecoms are probably not the only ones who would be attracted to SkyTower's product. "In addition to commercial interest in SkyTower's telecommunication infrastructure, there is strong and growing government interest in AeroVironment's UAVs (Unmanned Aerial Vehicles), especially given the current defence needs," said Tim Conver, AeroVironment's chief executive. "Government interest ranges from broadband battlefield communications to emergency backup telecom services."
In September, NASA will be sponsoring an agricultural remote sensing mission, using the Pathfinder Plus aircraft equipped with multi-spectral imaging equipment to conduct several studies, including demonstrating how crop yields could be optimised by identifying factors such as the optimal time to harvest, required changes in irrigation levels and outbreak of crop disease.
The company claims that it could launch the airplane on a commercial basis by 2005 but did not say which companies it is working with.
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