Sorry, GPS L1 is, of course, 1575.42 MHz (or 1.57542 GHz).
Charles
Stanley wrote:
Wonder if the clients of this network reduce power as cell phones
do to increase battery life and reduce interference or they will
use a dish on the fixed clients, not that would help with
interference from the sat. The web site reads like the sat will
distribute the internet signal direct to the clients
The issue is not signals from satellites, which are very
weak. Satellite operators serving mobile and portable devices
(which generally cannot employ high-gain, narrow-beamwidth antennas
like the dish antennas used for stationary ("fixed," in FCC
parlance) satellite services such as direct-to-home television
reception) have found that there are significant coverage "holes"
and have asked the FCC to allow them to use an "ancillary
terrestrial component" ("ATC") -- i.e., base transcievers on towers,
like cellular base stations -- to cover the holes. The ATC rules,
as they are currently written, require the ATC component to be
ancillary to and integrated with a robust satellite system that is
available to all system users (the "integrated service" rule).
Even with ATC, the Mobile Satellite Service ("MSS") has never really
caught on, so it represents a fair chunk of spectrum getting very
little use. Some MSS providers seek to create primarily-terrestrial
systems with an essentially vestigial satellite component. The FCC
(in its National Broadband Plan -- see
http://www.broadband.gov/plan/) has started to move toward allowing
terrestrial-only services to operate on a co-primary basis with the
MSS on MSS spectrum, which has emboldened MSS
licensees. Lightsquared, which is an MSS licensee, petitioned for a
conditional waiver of the "integrated service" rule, which the FCC granted:
http://fjallfoss.fcc.gov/edocs_public/attachmatch/DA-11-133A1.pdf
One of the conditions imposed by the FCC was "the creation of a
process to address interference concerns regarding GPS and, further,
that this process must be completed to the Commission's satisfaction
before LightSquared commences offering commercial service, pursuant
to the approval of its request, on its L-Band MSS
frequencies." This process is expected to be completed within 90
days. See paragraphs 39-43 of the FCC order linked above.
So: The FCC seems determined to allow the expanded use of L-band
MSS frequencies for terrestrial use to deliver mobile broadband
services, and Lightsquared is just one company looking to
benefit. The primary threat to GPS (GPS L1 is 1575.42 GHz) is from
terrestrial base stations serving mobile devices and operating up to
1.559 GHz, although millions of mobile handsets operating between
1.6265 and 1.6605 GHz may also be a worry.
The FCC has made way more than its share of boneheaded technical
decisions over the decades (to name just the most visible tip of the
iceberg: NTSC, multiplexed FM stereo, NRSC preemphasis of AM
signals, AM stereo, forcing the switch to digital television, choice
of ATSC/8VSB as the digital television standard, choice of IBOC as
the AM/FM digital radio standard, etc., etc. -- and that's just in
the broadcast area). This time, it's a mad, desperate dash to find
500 MHz of spectrum usable for mobile broadband in the next 5 years.
In my view, this technical tone-deafness at the FCC persists because
there has been no engineering expertise or background at the
Commission(er) level since ... well, I'm not sure there ever was,
but perhaps in the 1930s-'40s. The FCC staff is supposed to provide
engineering support, but Commissioners often do not listen to the
staff as carefully as they should and sometimes the staff gets it
wrong. IMO, the 5-person Commission should always include at least
one engineer and one economist so that at least in theory it has
enough expertise to do a reality check on proposals at the Commission level.
Thus, the truth (at least as I see it) is much more complicated than
a simplistic conspiracy theory -- but then, it always is.
Best regards,
Charles
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