By Keir Thomas, PCWorld
For years, the flight attendants asked passengers to turn off personal electronic equipment before take off flights. This is because these devices are not screened electromagnetically aviation standards and therefore may interfere with the airplane electronics. It is a slight risk, but it is worth taking seriously.
However, the risk could become significantly higher in the future if you fly with a 4 G phone with proposals for new services incurred by technology from LightSquared, a startup that hopes to create its own mobile network LTE rival the likes of Sprint and Verizon.
At least this is according to the creator of Garmin GPS technology, which showed that he proposed to LightSquared technology can interfere seriously with global positioning system signals.
Clearly the telephony services implementation of next generation isn't going to be smooth. Meanwhile, on the issue of signal interference, LTE cellular European users may want to keep their phones away from their televisions if they don't want to encode the image.
In both cases, the problems concerning radio frequencies. LightSquared aims to offer a service in the United States which operates LTE in the range of 1525 to 1559MHz. Is worrying close to 1559 1610MHz bandwidth used for GPS--too close for comfort, actually.
Cell phone towers pump signals significantly greater power than it uses GPS and Garmin has shown that no one could even take a cellular Tower errant to cause problems. Creating a radio frequency transmitter LightSquared, Garmin's proposals failed to knock out the GPS correction of one of its most popular consumer devices when he was little more than half a mile away.
More worrying, Garmin aviation devices sells lost his GPS location at a distance of just under 14 kilometres away and it was completely jammed five and a half miles away (click here for Garmin's report (PDF)).
And that is caused by a single transmitter. Cell phone towers work by a grid of many transmitters that hand calls to and from the other. With most transmitters in a city, GPS are likely to be killed and deaths within range in the skies above too.
However, LightSquared is confident that it can overcome the problems of contamination of frequency, saying that its "full commercial service implementation to meet the concerns about the possibility of unintentional interference to certain GPS devices."
In other words, is the word of LightSquared against Garmin.
Elsewhere in the world, the EU is proposing that old analog TV frequencies around 800 MHz used for European G 4 networks now that everyone has moved to digital TV, which uses a different frequency range and smaller. However, cable TV services in Europe, yet data pipe down these frequencies coaxial lines analog, old. Using a mobile LTE European into a room near a TV cable has been shown to disrupt the image and damage the data services. (Click here (PDF) for a study carried out by an agency of the Government U.K. proving the effect.)
The basic problem is that how efficient their digital services replace equivalent analog-they monopolized the radio spectrum band, national Governments are eager to sell the space radio abruptly unoccupied. However, as demonstrated by test of Garmin, these services do not always sit comfortably next to each other.
In an ideal world there would simply start all over again and assign the frequencies to digital services in a reasonable manner, but current systems of cellular networks, Wi-Fi and GPS all emerged organically over many years, during which they had to co-exist peacefully with nearby analog services.
Other 4 G, LTE services are safe. For example, the Sprint WiMAX service operates at 2500MHz and Verizon LTE 700 MHz. Or are known to cause problems.
However, it is now clear that a competitive market, combined with the limited opportunities of spectrum means that service providers will have to tread very carefully as they roll out faster telephony services in the coming years.
Reprinted with permission PCWorld.com from. Story copyright 2011 PC World Communications. All rights reserved.
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