[aprssig] Terrestrial Threat to GPS Has Now Hit The Mainstream Media.

[John L. Wilson]

I found this article today.  It includes a video describing the issue and
has links to other sources of information.

http://www.lightreading.com/document.asp?doc_id=206519&#msgs

Monty Wilson, NR0A
jwilson at ncfcomm.com
-----Original Message-----
From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] On Behalf
Of Stephen H. Smith
Sent: Thursday, April 07, 2011 4:30 AM
To: TAPR APRS Mailing List
Subject: [aprssig] Terrestrial Threat to GPS Has Now Hit The Mainstream
Media.

News of the terrestrial wireless broadband network that threatens to
overload and block GPS receivers, that I posted about around a month ago has
now hit the mainstream media.

[The issue, if you missed my original post, is that the FCC, in it's
infinite idiocy, has authorized a terrestrial network to be built in
spectrum directly adjacent to the 1575 MHz GPS frequency. This spectrum,
previously used for satellite communications, will now have 10s of thousands
of ground-based transmitters radiating signals millions of times stronger
than those from satellites, which will cause major overloading,
desensitizing or blocking of GPS receivers in many areas.]

AP News via Yahoo! News

<http://news.yahoo.com/s/ap/20110406/ap_on_hi_te/us_tec_gps_threats>


  Planned wireless Internet network threatens GPS

By JOELLE TESSLER, AP Technology Writer Joelle Tessler, Ap Technology Writer
- Wed Apr 6, 3:02 pm ET

WASHINGTON - A new, ultra-fast wireless Internet network is threatening to
overpower GPS signals across the U.S. and interfere with everything from
airplanes to police cars to consumer navigation devices.

The problem stems from a recent government decision to let a Virginia
company called LightSquared build a nationwide broadband network using
airwaves next to those used for GPS. Manufacturers of GPS equipment warn
that strong signals from the planned network could jam existing navigation
systems.

A technical fix could be expensive - billions of dollars by one estimate -
and there's no agreement on who should pay. Government officials pledge to
block LightSquared from turning on its network as scheduled this year unless
they receive assurances that GPS systems will still work.

The stakes are high not only for the GPS industry and its users, but also
for those who would use LightSquared's network. In approving it, the Federal
Communications Commission seeks to boost wireless competition and bring
faster and cheaper Internet connections to all Americans - even in remote
corners of the country.

LightSquared and the FCC both insist the new network can co-exist with GPS
systems. But device makers fear GPS signals will suffer the way a radio
station can get drowned out by a stronger broadcast in a nearby channel.

The problem, they say, is that sensitive satellite receivers - designed to
pick up relatively weak signals coming from space - could be overwhelmed
when LightSquared starts sending high-power signals from as many as 40,000
transmitters on the ground using the airwaves next door.

"The potential impact of GPS interference is so vast, it's hard to get your
head around," said Jim Kirkland, vice president and general counsel of
Trimble Navigation Ltd., which makes GPS systems. "Think 40,000 GPS dead
spots covering millions of square miles in cities and towns throughout the
U.S."

One of the biggest risks is to the GPS navigation systems used by about 40
percent of commercial and private planes. Backup systems that rely on
ground-based radio signals are not as accurate and have coverage gaps. Some
older private planes have no backup at all.

With GPS interference, a pilot "may go off course and not even realize it," 
said Chris Dancy, a spokesman for the Aircraft Owners and Pilots
Association.

LightSquared's network could also undermine the Federal Aviation
Administration's multi-billion-dollar program to upgrade the nation's
air-traffic control system, which is based on World War II-era radar
technology.

The new GPS-based system is more precise and lets planes fly more direct
routes. That will save airlines time, money and fuel and cut pollution. It
is also key to accommodating projected increases in airline traffic by
enabling planes to fly safely closer together.

Public-safety officials, too, are nervous about LightSquared because they
rely on GPS to track and dispatch police cars, fire trucks and ambulances.
Many 911 systems also use GPS to help locate people. Disruptions could delay
responses to emergencies, said Harlin McEwen, an official with the
International Association of Chiefs of Police.

Even the Pentagon has expressed concern as it relies on GPS to guide planes,
ships, armored vehicles, weapons and troops.

LightSquared plans to compete nationally with super-fast, fourth-generation
wireless services being rolled out by the likes of AT&T and Verizon
Wireless. 
It won't sell directly to consumers, though. Instead, LightSquared will
provide network access to companies including Leap Wireless, parent of the
Cricket phone service, and Best Buy, which will rebrand the service under
its own name.

LightSquared has its roots as a satellite-phone operator, so its airwaves
historically have been reserved primarily for satellite communications. FCC
rules adopted in 2003 allowed the company to back up those signals with
ground-based wireless service, but only to fill in coverage gaps.

In January, however, the FCC gave LightSquared permission to use its
airwaves for a broader, conventional wireless data network. Although the
company will continue to offer satellite service too, it plans to cover at
least 92 percent of Americans by 2015 with high-power wireless signals
transmitted by base stations on earth.

Until now, GPS receivers haven't had much trouble filtering out noise in the
adjacent airwaves because it consisted mostly of low-power signals beamed
from space. But GPS manufacturers warn that will change once there is a
major ground-based broadband network next door.

Both LightSquared and the FCC say further testing is needed to determine the
true extent of any interference. The FCC is requiring LightSquared to
participate in a study group with GPS manufacturers and users.

LightSquared won't be allowed to start operating its network until the
government is satisfied that any problems are addressed, FCC spokesman Rob
Kenny said.

"We have every reason to resolve these concerns because we want to make sure
there is a robust GPS system," LightSquared executive vice president Jeffrey
Carlisle said.

Dan Hays, a consultant with the firm PRTM, insists the technical solution is
straightforward: GPS devices need to include better filters to screen out
the LightSquared signals.

Estimates on the costs of a fix, however, range widely.

Hays believes it will cost no more than $12 million - or 30 cents per device
- to install better filters in roughly 40 million standalone GPS units made
worldwide each year. Cell phones, he said, will be fine because they don't
rely solely on GPS to determine location and have better filters anyway.

But Tim Farrar, a consultant with TMF Associates, insists cellphones need
upgrades, too - raising the annual cost to as much as $1 billion.

Tens of billions of dollars of existing equipment may also need to be
replaced, Farrar said.

GPS manufacturers insist that neither they nor their customers should have
to pay.

That's because GPS receivers were designed to screen out low-power signals
next door, and now the government is changing the rules, said Scott Burgett,
software engineering manager with Garmin Ltd.

But Hays said GPS receivers are "eavesdropping on signals outside of where
they are supposed to be" - in LightSquared's space.

That was not a problem - until now.

Moreover, LightSquared and the FCC say the GPS industry should have been
preparing for a ground-based network nearby since the FCC first allowed
backup wireless systems in that space in 2003.

The real dilemma, Hays said, is this: "This is a situation where the
neighbor built the fence too far over the property line and may not have
realized it at the time. Now the other neighbor wants to build a pool and
there is not enough space. So the question is: who has to pay to move the
fence?"

___

Associated Press Writer Joan Lowy in Washington contributed to this report.





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