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 GPS in Peril?

Special Report for Duckworks Magazine
By Gary and Helen Blankenship

Imagine an improved wireless broadband network that lets you download movies or other data-intensive Internet content while your afloat. That's pretty neat.

The downside, according to critics, is that while you're watching "Titanic," your boat may run on the rocks because the broadband signal interferes with the operation of your GPS.

A private company's proposal to create a wireless broadband system has created a storm of controversy from a wide range of GPS manufacturers and users who say the frequencies used by the company could interfere with the GPS units in everything from boats and cars to airplanes and cell phones.

LightSquared, the company setting up the broadband system, received conditional approval from the Federal Communications Commission in January for its land-based transmitters (it also has satellites). LightSquared wants to use radio frequencies near those used by GPS signals. However, a FCC technical subcommittee found interference with GPS signals and the FCC is accepting comments for a 30-day period, which ends July 30.

A large group of GPS manufacturers and users, the Coalition to Save Our GPS, has banded together in a group to fight the LightSquared proposal. "LightSquared's planned use of the spectrum is dramatically different from the limited 'ancillary' ground-based use previously permitted by FCC rules, and is incompatible with GPS," the coalition says.

According to a release from BoatU.S., a group that represented boat owners and a member of the coalition, "The company [LightSquared] has proposed to build 40,000 ground stations. LightSquared's high-powered ground-based transmissions from these stations have [been] shown to cause interference in hundreds of millions of GPS receivers across a wide range of uses, including aviation, marine, emergency response and industrial users such as delivery and trucking companies. A new report requested by the FCC says, 'all phases of the LightSquared deployment plan will result in widespread harmful interference to GPS signals and service and that mitigation is not possible.'"

As this article is published, the battle is ongoing. LightSquared said it has solved most of the technical problems highlighted by the FCC report, while a spokesperson for the coalition called that claim "bizarre."

"Initial testing did indeed show interference with GPS. Last month [June], LightSquared announced a new launch plan that resolves the interference issue for 99.5 percent of all commercial GPS devices," said Christopher Stern, a spokesperson for LightSquared. "The company is committed to working with the relatively small number of commercial GPS devices that are still affected by LightSquared's nationwide, high speed wireless network. Those affected devices are almost exclusively precision devices used in agriculture and construction – not the kind of navigation devices used in boats."

LightSquared's original plan was to use broadcast frequencies in the 1545 to 1555 Mhz range, he said. That is close to the 1559-1610 Mhz frequencies used by GPS. The company is now proposing to use 1526 to 1536 Mhz., although critics say its eventual plans still call for using the higher range.

Stern also said the problem is not that LightSquared broadcasts are "leaking" over into GPS frequencies, as claimed by opponents. "The current issue is caused because some GPS device makers are 'listening' to frequencies assigned to LightSquared," Stern said. "For instance, recent testing showed that the 300 million GPS enabled cell phones are not affected by LightSquared's pending launch. That's because they planned ahead and developed a five-cent filter that solves the problem for their consumers."

"We take strong exception to both the proposal [LightSquared's solution] and the statement that it resolved 99.5 percent of the interference issues," said Dale Leibach, a spokesperson for the coalition. "The best description of that proposal is 'bizarre.'"

He also disputed that the problem is GPS units hearing the extra frequencies and not LightSquared's frequencies spilling over.

"Some LightSquared signal does 'leak' into the GPS band, increasing the noise inside the GPS band by up to 20 percent," Leibach said. "Regarding 'listening' to the LightSquared's band, GPS receivers were shown in the tests to be able to reject signals in the adjacent band thousands or even millions of times more powerful than the distant whisper of a GPS signal from space that has to be tracked. Rejecting signals that much more powerful can hardly be described as "listening". The problem, as the tests showed, is that LightSquared designed a network that would overwhelm GPS receivers with signals in the adjacent band that were measured to be up to 800 billion times more powerful than the distant, low powered GPS signals."

According to a coalition release, LightSquared would use the lower frequencies initially but eventually would use the band next to the GPS frequencies. It also said a company offer to reduce the broadcast power of its towers was actually the same power that was used in the FCC tests.

Margaret Podlich, vice president for Government Affairs with BoatUS, said that when LightSquared saw the problems with the higher frequencies, it announced its plan to use the lower range, but it's not clear those won't affect GPS reception.

"They [the FCC] started testing at the higher spectrum, because that's LightSquared's proposal. When that didn't work out, LightSquared went to a different plan, and that's not what was tested," Podlich said. "From the industry perspective, that has not been proven [that those frequencies are safe] because that has not been tested. From my perspective, there's another whole round of testing that needs to be done."

The coalition, in its press release, expanded on that view: "LightSquared's 'solution' is not a move to an alternative frequency band. Nor is it a reduction in power relative to what has been tested from the beginning. The 'solution' would cause massive disruption to millions of Americans in their everyday lives as well as to many critical U.S. economic sectors, later followed – after the 'next several years' – by even more interference to more GPS users. The conclusion from the information below is inescapable: The only real solution to the LightSquared interference problem is to move out of the MSS band [frequencies near those used by GPS] altogether."

The coalition said using the adjacent frequencies is not a problem from LightSquared's satellites, but it is when they are used by powerful ground stations.
Different frequencies should be used there according to the coalition.

LightSquared has understated the extent of interference with high precision GPS users, the coalition said. Those are used in a variety of agricultural, construction, government and other uses. Of interest to boaters, the Global Maritime Distress and Safety Systems suffered a complete loss of GPS and satellite signals during the FCC's test, according to the coalition, and overall, 94 percent of high precision GPS uses suffered interference during the tests.

Podlich argued that the FCC has a broader duty than just considering LightSquared's needs, noting that she has GPS units in her car, phone, and boat.

"I rely on GPS in my life, I rely on it on the water and I don't want the federal government to compromise it in each of our lives for the benefit of a private company," Podlich said. "This raises so many questions about the integrity of the GPS system for millions of customers. . . . LightSquared has gone and bought a band width and found it's not going to work the way they want it. The FCC has to do the right thing. In this country we try to trust the federal government to protect common resources, whether its water, whether its air, whether it's wavelength. We need to pressure the FCC to protect the public trust instead of a private company."

The coalition has more than 70 members, including GPS manufacturers Trimble, Magellan, TomTom, and Garmin. It has dozens more associate members.

It is not clear when the LightSquared wireless broadband, assuming it gets final FCC clearance, might begin operation. A question to the company on where and when operations might began drew the response from Stern that, "The service in question has not yet been launched."

Podlich said it's uncertain when the FCC might give it's final decision, because the entire process for LightSquared has apparently been put on a fast track, in keeping with a federal government goal of bringing Internet and broadband services to the entire country, including rural areas. Reaching rural areas is one of LightSquared's stated goals.

"We have 15 days to get comments in, and that's the most important deadline," Podlich said. After July 30, there will be a 15-day period where the FCC will accept "comments on the comments," she said, but then the schedule is uncertain.

LightSquared will not offer broadband service directly to customers. According to the company's website, "As a wholesale-only operator, LightSquared will deploy an open 4G network to be used by existing and new service providers to sell their own devices, applications and services – at a competitive cost and without retail competition from LightSquared."

Ironically, while LightSquared may be a problem for boaters using GPS, its system could bring broadband services to them while afloat.

"One unique element to LightSquared's network is an integrated satellite and terrestrial network," said Stern. "So if a boater is out of range of the terrestrial network he or she would have access to the satellite network. One important point. LightSquared intends to be the nation's first wholesale wireless network and the service the boater would subscribe to would be purchased from one of LightSquared's customers such as Best Buy or Leap Wireless."

Want to find out more about this issue? Check these:

  • LightSquared's website:
  • Coalition to Save Our GPS:
  • A BoatU.S. press release on the topic. This includes a link to send a comment to the FCC and a sample message for those who oppose the LightSquared project:
  • This BoatU.S. webpage has a link to the FCC's technical report: Scroll down and click on the link to "GPS Working Group Final Report." The report is more than 300 pages and may take a while to download.
  • For instructions on how to comment directly to the FCC (refer to FCC IB Docket No. 11-109, Interference with GPS Signals): Remember, comments must be filed by July 30.

If you want to discuss this issue further -- and/or if you have the technical expertise to evaluate some of these competing claims -- your comments are welcomed on the Duckworks Forum on Yahoo Groups.

© 2011, Gary and Helen Blankenship

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