[aprssig] LightSquared GPS Interference Issue Flares Again in Senators' Letter

Fri Apr 15 13:43:02 EDT 2011

http://www.wirelessweek.com/News/2011/04/Policy-and-Industry-LightSquared-GPS-Interference-Senators-Letter-Government/?et_cid=1411150&et_rid=54167317&linkid=http%3a%2f%2fwww.wirelessweek.com%2fNews%2f2011%2f04%2fPolicy-and-Industry-LightSquared-GPS-Interference-Senators-Letter-Government%2f

*LightSquared GPS Interference Issue Flares Again in Senators' Letter*

Senators Pat Roberts (R-Kan.) and Ben Nelson (D-Neb.) want the FCC to stop
LightSquared from deploying its LTE network until it proves its service
doesn't interfere with GPS services.

In an open letter released yesterday, the lawmakers asked their fellow
senators to call on the FCC to ensure that GPS service is not compromised in
any way by LightSquared's planned hybrid-satellite LTE network.

LightSquared plans to deploy its services on spectrum directly adjacent to
GPS bands. The company has developed filters to stop its signal from
bleeding into GPS service, but major GPS stakeholders, including the Defense
Department, fear that widespread GPS "dead zones" are inevitable if
LightSquared's network goes live.

"The full Commission must be involved and require LightSquared to
objectively demonstrate non-interference as a condition prior to any
operation of its proposed service," the Senators wrote in their letter.
"Anything less is an unacceptable risk to public safety."

GPS systems are used by the military, public safety, aviation and consumers.
The technology is also used in critical applications across a wide swath of
U.S. industries, including agriculture and civil engineering.

LightSquared received a
waiver<http://www.wirelessweek.com/News/2011/01/carriers-FCC-Clears-Spectrum-Restrictions-for-LightSquared/>from
the FCC earlier this year to use spectrum formerly reserved for
satellite services for land-based LTE services. The L-Band spectrum is
located next to bandwidth used by highly sensitive GPS receivers, which also
use parts of the L-Band spectrum to fine-tune their coordinates.

Many in the GPS industry say the signal sent out by LightSquared's network
of 40,000 base stations will create major interference problems that will
overwhelm GPS receivers.

"LightSquared is trying to define the potential for interference in a very
narrow way – if they filter it so none of the signals go out of their band,
that's all they have to do," says Jim Kirkland, general counsel at Trimble.
"They say we're eavesdropping on their band, but I would say we can't help
but hearing what they're doing in their band."

The FCC has said it will not allow LightSquared to launch commercial
services until the GPS interference issue is addressed, but that has done
little to assuage fears of the GPS
industry<http://www.wirelessweek.com/News/2011/03/Technology-Group-Targets-LightSquared-GPS-Interference-Wireless-Networks/>.

SkyTerra, which later became part of LightSquared, first proposed
incorporating a land-based component into its L-Band satellite services in
2003. The company also worked with the U.S. GPS Industry Council (USGIC) at
the time to manage interference posed by out of band emissions.

Manufacturers of GPS equipment continued building receivers that listened in
to portions of the L-Band after 2003, a practice Kirkland says is for
legitimate technical and business reasons.

Jeff Carlisle, head of government and regulatory affairs at LightSquared,
says GPS receivers should have been designed differently after 2003. The FCC
does not regulate receivers, only transmitters, adding to the complexity of
the issue.

"Even though our transmitter is doing exactly what it's supposed to do and
not sending any signal into GPS, the receiver is looking into our spectrum
either by accident or design," Carlisle said in an interview conducted
earlier this month. "There's no problem with that until the receiver crosses
the boundary into our area. After 2003, the receivers should have been
designed so they were protecting themselves from that interference."

LightSquared says it spent $9 million to develop filters to minimize
interference issues and has formed an FCC-mandated technical working group
with the U.S. GPS Industry Council (USGIC) to study the issue. LightSquared
is set to file a new report from the technical working group today.

Carlisle said in a statement that LightSquared is confident the interference
issues can be addressed, and reiterated the company's intention to launch
commercial operations only after the FCC is satisfied with the review
process.

"To ensure that the LightSquared network and the GPS systems can coexist, we
will continue to work collaboratively with federal agencies and the GPS
community, just as we have over the past ten years since the proposed scope
of LightSquared's terrestrial network was first publicly announced,"
Carlisle said.

LightSquared has already signed up Best Buy and Cricket
Communications<http://www.wirelessweek.com/News/2011/03/Technology-Preparing-Liftoff-LightSquared-Company-Wireless-Networks/>for
its wholesale LTE service and plans to begin commercial operations in
the first quarter of next year. It is not clear whether the issues with
potential GPS interference could affect the company's launch plans.

-- 
Tyler Griffiths
N7UWX

See where I am:
http://map.findu.com/n7uwx-12
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.tapr.org/pipermail/aprssig_lists.tapr.org/attachments/20110415/02b511b6/attachment.html>