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Senator Uses FCC Nomination Process To Question National Wireless Network
K7DAN contributes this excerpt from the intersection of politics, regulation, and high technology: "Sen. Charles Grassley is standing by his threat to place a hold on two nominees to the Federal Communications Commission over concerns about a controversial new wireless network the agency has allowed to move forward. The Iowa Republican this week accused the FCC of refusing to comply with his requests for information on its discussions with Virginia company LightSquared regarding its next-generation national wireless network. Some fear the network would hinder the effectiveness of high-precision GPS systems — used by the military, farmers and others. Grassley also raised questions about the involvement of Harbinger, the hedge fund behind the project and founded by Democratic donor Philip Falcone."
Maybe if GPS manufacturers hadn't disregarded the DOD requirements on GPS, the technology wouldn't mess with your GPS http://m.lightsquared.com/press-room/press-releases/gps-industrys-failure-to-comply-with-department-of-defense/
Imagine I bought a timeshare for 2 weeks a year and noticed that nobody was using the week after mine and I started planning 3 weeks stays. A few years down the road, somebody else shows up and wants to stay during that third week. What right would I have to be pissed?
Personally, I'm more concerned to find out that it's apparently really easy to knock out military GPS.... It seems like somebody would want to fix that rather than complain about spectrum usage. Just my 2 cents.
I don't have time to make a sig
They're doing some crazy testing to make sure that it won't interfere. They're not going to deploy a technology that could take down the entire US without making damn sure it won't. Besides, Garmin's guys are the ones saying it'll mess everything up- testing sponsored by LightSquared shows that is has a small effect, if any. I don't think they'd bias the tests- most of those labs, if not all, are good labs.
Sent from my CR-48
The issue at hand is that Lightsquared plans to place strong, satellite-based signals very close in frequency to that of the GPS system -- specifically, signals at 1526-1536 MHz (initially; although Lightsquared has rights to 1525-1559 MHz) that will be 60 dB stronger on the Earth's surface than the GPS L1 signals at 1575.42 MHz.
Since GPS signals are so weak (-130 to -150 dBm at the receive antenna terminals), most GPS receivers have minimal RF filtering, to avoid the insertion loss of the filters and thereby optimize GPS receiver sensitivity. Recognizing that GPS receivers do not have sharp selectivity, for decades it has been national policy (as well as good engineering practice) not to place strong signals near the GPS frequencies. This change in policy is the issue at hand.
Technically, the problem with the Lightsquared proposal is, even if the Lightsquared guys put lots of filtering on their transmitter, so that it is spectrally clean and has substantially no energy at the GPS frequency itself, the millions of existing GPS receivers already in the field will be unable to receive the desired L1 signal in the presence of the strong undesired Lightsquared signal, due to their limited filtering and dynamic range -- and, short of replacing every GPS receiver in the country, there's nothing Lightsquared can do about that.
Why Lightsquared thinks this scheme will work, and they won't be vilified in the press once GPS problems crop up, is something for the psychologists and sociologists to ponder.
Big Time Obama Donors are trying to get approval from the Obama FCC for something that might conflict with GPS. The Big Time Obama Donors are accused of exerting inappropriate political pressure on the FCC. The Republican in charge of FCC oversight wants to hold a hearing to check and make sure that the thing doesn't conflict with GPS (and that the FCC wasn't inappropriately pressured.)
Only a hack can read that and see "Republicans are evil." This is a pretty textbook example of the Legislative Branch acting as a check on the Executive Branch. This is EXACTLY how things are supposed to work.
By commercially viable you really mean cheapskates who failed to implement the recommended guidelines because it would have increased the component count and cost and are now screaming foul because their own devices cannot block out the adjacent band transmission because they failed to implement the proper rejection into their devices...
Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
Then your understanding would be wrong. Lightsquared wants to set up an LTE network, with nationwide coverage. They would use terrestrial stations transmitting on frequencies immediately adjacent to GPS frequencies. The terrestrial stations would cover areas of dense population, and rural areas would be covered by satellite.
These frequencies were formerly allotted solely to satellite use. Lightsquared got someone at the FCC to do a fast track (public comment period of only 7 business days after announcement, and across Thanksgiving holiday 2010) approval for also using these frequencies terrestrially.
The problem is, terrestrial signals are MUCH closer/stronger than satellite ones, and many/most GPS receivers were designed based on adjacent signals having a satellite-level strength, and therefore are subject to interference from Lightsquared's terrestrial signals.
This isn't so much a political thing (except perhaps how Lightsquared's approval got fast tracked), but a technical one.
Here's something describing the situation as GPS users see it, and another, which describes the fast tracking which was done:
"National Security is the chief cause of national insecurity." - Celine's First Law
There is stuff that you can do here but it would be expensive and possibly power hungry (some GPS receivers have to run off of batteries).
Normally this issue is resolved by placing guard bands around downlink bands where terrestrial transmitters are not allowed. By not doing this in a reasonable way, the FCC has simply messed up.
The one thing you left out of your informative post is that Lightsquared bought the radio spectrum it intends to use for cheap because it was restricted to satellite use. If they can convert that to terrestrial use they make a cool 500% profit ($2 billion vs $12 billion according to this link http://www.generalaviationnews.com/2011/10/27/coalition-debunks-claims-by-lightsquared-on-gps-issue/) on the radio spectrum. Those of us in the casual GPS user community have watched this unfold in disbelief that the FCC would allow something to shut down most of the existing GPS receivers in the country. I at least figured that the FAA and military would step in and put and end to this. Lightsquared must really have some political juice in Washington DC.