[Boatanchors] LightSquared

Robert Nickels ranickel at comcast.net
Mon Oct 8 16:07:54 EDT 2012


I suspect everyone is in violent agreement that the Lightsquared plan to 
use spectrum adjacent to the GPS freqencies was a horrible idea and this 
is why the GPS industry has been fighting it for the past two years. The 
issue isn't Lightsquared per se, after all their original plan was to 
built a new LTE network that could increase competition and reduce 
broadband cost, which on it's own, wasn't a bad thing. The two major 
problems were the 1) their choice of spectrum (adjacent to GPS where 
their ground-based base stations would cause totally unacceptable levels 
of interference, and 2) the backdoor way they went about getting this 
allocation approved by FCC without diligent technical review or testing 
-- but that takes us into the realm of partisan politics so I won't say 
more about it here.

The following excerpt from a report written by Garmin in January 2011 
provides a good overview of the history and the impact the technically 
incompetent Lightsquared plan to modify how these frequencies are used 
would have had on GPS services. (I will leave the question of why our 
FCC failed to recognize these flaws and approved it anyhow to the reader)

"On November 18, 2010 l.ightSquared Subsidiary LLC filed an application 
requesting modification of its
authority for Ancillary Terrestrial Component (FCC File No. 
SAT-MOD-20101118-00239) of L Band 1 M55
(Mobile Satellite Service). This application proposes to fundamentally 
change the usage of the L Band 1
spectrum (1525 MHz- 1559 MHz) from MSS (very low power, space to earth 
signals) to fixed, high
power, terrestrial broadband service. The L Band 1 is adjacent to the 
GPS band (1559 MHz - 1610 MHz)
where the GPS and other satellite based radio navigation systems operate.

If this modification is approved, widespread, severe GPS jamming will 
occur. In careful, experimental
testing at Garmin using the technical details (power, frequency, 
modulation bandwidth) of the proposed
l.ightSquared system, two common state-of-the-art Garmin GPS receivers 
experienced significant
jamming within a radius of several miles from a simulated Lightsquared 
transmitter.

The nuvi 265W, a very common portable oonsumer automotive navigation 
device, began to be jammed
at a power level that represents a distance of 3.6 miles (5.8 
kilometers) from the transmitter. The nuvi
265W lost a fix at a distance of 0.66 miles (1.1 kilometers) from the 
transmitter.

A GNS 430W, a common FAA certified General Aviation receiver that 
suports the FAA’s NextGen RNAV
and RNP operations, began to be jammed at a distance of 13.8 miles (22.1 
kilometers) from the
Lightsquared transmitter. Total loss of fix occurred at a distance of 
5.6 miles (9.0 kilometers) from the
Ughtsquared transmitter. This GPS receiver is certified for LPV 
(localizer Performance with Vertical
guidance) approach operations to 200 feet decision height, yet will be 
completely jammed by
Lightsquared transmitters over 5.6 miles (9.0 kilometers) away. Further, 
due to the special FAA
requirements that this receiver is designed to meet, it takes on the 
order of 90 seconds to regain a fix
once lost."

Lightsquared expended a great deal of political and financial capital 
fighting this losing battle, but remains alive (albeit just barely, in 
Chapter 11). Their latest plan to resolve the technical problem while 
staying in business can be read here: 
http://www.wirelessweek.com/News/2012/10/lightsquared-latest-lte-plan-share-federal-spectrum/

While moving up to the proposed new band seems to eliminate the 
immediate threat, I suspect most GPS industry observers won't feel 
comfortable unless and until the adjacent segment (1.526-1.536 Ghz) is 
taken away and reserved as a perpetual guard-band around the critical 
GPS allocation.

I don't believe in punishing entrepreneurs and businesses, but when a 
company so egregiously acts against to the public interest, it may not 
deserve a second chance.

73 Bob W9RAN


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