Courtesy of SURVICE Engineering
These color-coded soundings were gathered by volunteer vessels participating in a test of whether recreational boats can contribute
chart data autonomously.
accommodate a new business plan to provide broadband
communications on a wholesale basis. It asked for
permission to offer its service using only ground-based
devices, rather than integrating satellite with limited
terrestrial services. In January 2011, the FCC granted
LightSquared the waiver on the condition that the plan
did not interfere with GPS systems.
Here’s the problem: GPS signals for boating and
other civilian uses are transmitted in the GPS L1 Band
at 1559–1610MHz. This band is directly adjacent to
the L-Band frequencies LightSquared wants to use, at
1525–1559MHz. Until the FCC waiver, the latter had
been reserved for space-to-earth signal transmissions.
Satellites get their power from solar panels. GPS
transmissions need a very quiet interference environment
because they must transmit a signal more than 12,000
miles using solar power amounting to just 50 watts or
less. GPS receivers are designed to be extremely sensitive
in order to lock on to these whispered signals and use a
LightSquared opponents coalesced into the “Save
Our GPS” lobbying group, whose founding members
include Garmin, Trimble Navigation, BoatU.S.,
and other organizations and individuals. Garmin’s
lawyers were particularly articulate in their arguments
against LightSquared, explaining to the FCC why
LightSquared’s transmissions are almost certain to
overwhelm GPS signals. And BoatU.S. representatives
hand-delivered 15,000 comments critical of LightSquared
to the FCC on the July 30 deadline for public comment.