4G network 'will create GPS dead zones across the US

[ShyWriter]

4G network 'will create GPS dead zones across the US

• 22 February 2011 by Jeff Hecht

WHAT would you rather have - a superfast data connection on your cellphone, or a reliable GPS signal to pinpoint your location? If a plan to install a network of base stations for the new 4G mobile wireless protocol goes ahead, it may mean you can have one but not the other.

GPS satellites transmit their navigation signals in the range 1559 to 1610 megahertz. Telecoms firm LightSquared of Reston, Virginia, has long communicated with its satellites using low-power signals in the adjacent frequency band, from 1525 to 1559 MHz, part of the "L band". Despite the closeness of the frequencies, satnav receivers have so far operated without any interference problems.

Bumpy road ahead for satnavs? (Image: Mario Beauregard/The Canadian Press/PA)

But in January, the US Federal Communications Commission (FCC) gave preliminary approval to a plan by LightSquared to build 40,000 new 4G base stations on the ground. These stations would broadcast much stronger signals in the 1525 to 1559 MHz range, to link to cellphones.

Based on lab simulations of the new transmissions, Scott Burgett and Bronson Hokuf, engineers with satnav manufacturer Garmin International in Olathe, Kansas, say this will seriously damage GPS reception. In a report to the FCC last month, they say that overlaps between the two systems are inevitable, and that this "will result in widespread, severe GPS jamming [and] will deny GPS service over vast areas of the United States".

Jeff Carlisle of LightSquared says it is the GPS receivers, not his company's base stations, that are at fault. "The issue is that some GPS receivers may be able to see into the L band where we operate," he told New Scientist.

The stakes are high. By 2015, LightSquared expects to spend $6 to $8 billion to complete the network, which promises to bring download speeds of 5 to 10 megabits per second to cellphone users. Meanwhile, over a billion GPS receivers are in use worldwide.

LightSquared has until 25 February to submit a plan to the FCC for working with the GPS industry and federal agencies to analyse interference issues; a final report detailing a solution is due by 15 June. LightSquared wants all future tests to be performed with real transmitters rather than simulators.

--END

~Shy

[mountaintree16]

Aw mannnn.....

[lelenina]

I would rather have a reliable GPS if it comes down to those two choices. Arriving at a correct destination is more important to me than being able to download a song a little faster.

[Amethyst]

GPS is now used by farm operations for seeding and spraying operations. We use this, along with auto-steer in the tractor for seeding. (The auto-steer unit won't fit in our sprayer, but we'll have it in our next sprayer, for sure.) Now life could get...really interesting (!) for farmers who use this technology out in the field if something starts interfering with that.

Actually, out here, G3 is just getting into place, so hopefully this thing is all figured out by the time G4 comes around.

[mountaintree16]

I agree lelenina & Amethyst. I'd much rather the GPS work normally.... if this happens there would be soo many problems...