[time-nuts] Lightsquared and a little math

[Charles P. Steinmetz]

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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