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Wireless Networking

FCC Bars Lightsquared From Using Airwaves 178

Posted by Unknown Lamer
from the lightsquared-disputes-laws-of-physics dept.
New submitter mc6809e writes with news that Lightsquared might have just been killed. From the article: "A proposed wireless broadband network that would provide voice and Internet service using airwaves once reserved for satellite-telephone transmissions should be shelved because it interferes with GPS technology, the Federal Communications Commission said Tuesday. The news appears to squash the near-term hopes for the network pushed by LightSquared, a Virginia company that is majority-owned by Philip Falcone, a New York hedge fund manager." LightSquared, naturally, continues to deny that the interference is real.
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FCC Bars Lightsquared From Using Airwaves

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  • by Anonymous Coward on Wednesday February 15, 2012 @10:08AM (#39043803)

    The FCC made a good and wise decision in this situation.

    It is unrealistic to expect the desires of a company which wants
    only to make money should override the safety of a public
    which depends increasingly on GPS.

  • by Anon E. Muss (808473) on Wednesday February 15, 2012 @10:09AM (#39043817)

    Really, the FCC and/or the GPS equipment manufacturer should be the ones being penalised.

    As a practical matter, there's no way to do that. If you allow Lightspeed to operate, you penalize the USERS of the (allegedly) badly designed GPS devices. It does suck to be Lightspeed, because GPS really is much more important than them.

  • by darkstar949 (697933) on Wednesday February 15, 2012 @10:18AM (#39043963)
    This has been coming up over on Ars Technica for awhile now and the explanation isn't so much that the GPS equipment is poorly designed but rather that Lighsquared is trying to use the spectrum in a way that it was not licensed to do so in. In short, the spectrum that they licensed is for low power satellite communications (i.e. GPS) and they want to use the same spectrum but to increase the power at which they broadcast it up to normal terrestrial levels. At that point the common analogy is that it is like trying to tell the color of a flashlight from a couple miles away: once you spot it you can tell when the color changes, but if someone comes along and places a high power search light next to it, the flashlight will drown out by the power of the other light source.

    Also, don't forget that radio signals aren't prefect pathways either and you can be broadcasting on one frequency and have it bleed over into another frequency. This is why radio stations and television channels are allocated in such a way that they aren't directly next to each other (think radio channel 100 and 100.1).

    So in summary, this isn't an equipment problem but a physics problem: making the equipment better isn't going to help the fact that the signal would be drown out if Lighsquared were to broadcast on a satellite channel at terrestrial power levels.
  • by tsj5j (1159013) on Wednesday February 15, 2012 @10:26AM (#39044037)

    The article seems to gloss over the most critical point that breaks this deal, painting LightSquared as a victim in the process:

    LightSquared's spectrum (which was bought from another company) was for SATELLITE transmissions, not TERRESTRIAL.
    Satellite spectrums are much cheaper, but can't be used for terrestrial transmissions.
    LightSquared is in fact trying to cheap out by using a cheaper spectrum.

    Analogy:
    LightSquared tried to buy a plot of cheap residential land to start a chemical/manufacturing plant, which affects nearby residents.
    They should have bought a piece of commercial land that supports their requirements.

    More technically:
    Satellite signals are weak as they are sent from huge distances from satellites with limited power. To receive these signals, the receivers must be tuned to be sensitive to these signals. If LightSquare were to transmit terrestrially from the bordering spectrum (to pass through walls and what-have-you), the transmitted strength will be thousands of times stronger than the GPS signals, invariably causing interference with GPS signals. Even if GPSes are built with a filter (which they shouldn't need to, the nearby spectrums should also be weak signals!), it would be prohibitively expensive/unfeasible to filter the strong terrestrial signals.

  • by smpoole7 (1467717) on Wednesday February 15, 2012 @10:36AM (#39044157) Homepage

    > you penalize the USERS of the (allegedly) badly designed GPS devices

    I maintain a 50,000 watt AM and two 100,000 watt FMs, and we get interference complaints all the time. The only fair rule for EVERYONE involved is to say, "as long as I'm following the terms of my license, and I'm SURE that my transmitter isn't putting out unwanted products, there's nothing I can do."

    I'm friendly; I offer tips and suggest filters; I help if I can. But there's really not much I can do if they have a cheap radio. Am I "penalizing" them for buying a $20 table radio from WalMart? I don't think so.

    You say "allegedly," but believe me, some of the cheap Chinese junk (albeit with good-sounding American brand names) being sold now isn't worth the money to crush and melt it. I would be astonished if the same isn't true of GPS equipment.

  • by fuzzyfuzzyfungus (1223518) on Wednesday February 15, 2012 @10:38AM (#39044179) Journal
    One wonders if Lightsquared thought that they had a good chance of pulling this off, either through technological optimism or confidence in their legal team(For whatever reason "Rural broadband!!!" appears to be the FCC's root password) or if this was some sort of long-odds/high-rewards gamble by the hedge fund chap...

    On the one hand, being able to convert a swath of satellite-to-ground spectrum into ground-ground spectrum would be crazy valuable, and likely result in some very nice returns. On the other, trying to go up against the now-firmly-entrenched users of GPS(ie. almost everybody) is a risky move indeed.

    Did they miscalculate the odds, or were they happy to take very bad odds for the possibility of extremely high returns?
  • by hamburger lady (218108) on Wednesday February 15, 2012 @10:40AM (#39044205)

    it's more like getting a permit to open a bar next door to an observatory but the city strictly requires you to keep your outdoor lighting to a minimum so as not to disturb the telescope next door. yet you still put up a huge neon sign and searchlight and when the observatory complains that your light pollution has ruined its ability to gather data, you say 'it's not my fault your telescope sucks'.

  • Fail. Just fail. (Score:5, Insightful)

    by DeadCatX2 (950953) on Wednesday February 15, 2012 @11:03AM (#39044505) Journal

    Let's rewind back to the year 2000.

    You're a hardware engineer. You've been tasked with building a GPS front end in a cost-effective manner.

    You decide to do your homework. You look up the FCC regulations for adjacent frequency bands. Since very high power terrestrial transmissions were prohibited by federal law (i.e. punishable by pound-me-in-the-ass federal prison time for violations), you run the calculations and decide how many -dB/octave your front-end filter needs to exclude signals that you could expect in real world applications.

    Sure, you could have gone with a filter that had 2x or 3x steeper roll-off. But why? Your manager asked you to do this in a cost-effective manner, and it's patently illegal for such strong signals to exist.

    So you're telling me that a hardware engineer who does his homework and designs a filter that can remove signals which are the maximum legal power is "shoddy"?

  • by Megane (129182) on Wednesday February 15, 2012 @11:07AM (#39044541) Homepage

    And what if someone decided to operate a station on an adjacent frequency channel, with 10 megawatts of power? Or even half a channel over? (Rules? What rules? We just want a little variance in the rules!) Then suddenly people trying to receive your station get interference because the channel separation rules weren't designed for that kind of power on adjacent channels? The problem isn't "badly designed GPS devices", it's that this is a band which was allocated specifically for the purpose of satellite communication, which is by its very nature rather low-powered to begin with.

    I'm almost surprised it took this long, except I'm sure there has been some ohbummer-related political interference going on behind the scenes. And it's probably still going on even now.

  • by thrich81 (1357561) on Wednesday February 15, 2012 @11:10AM (#39044595)

    Does it appear to anyone else that at least half the Lightspeed defenders must be paid shills for the company? Think about it -- GPS has been around for 20+ years and is considered a utility now, the facts of Lightspeed's purchase of the spectrum (only intended for satellite use) are not in question, and neither is the physics of humongously strong signals next to a band where the signals are below the noise floor. And, who gets all excited about some company's spectrum license unless have a vested interest -- it's not usually of much general interest. I'd like to be proved wrong so I can continue to trust he integrity of sites like /. but I'd say , "Reader beware".

  • by sirwired (27582) on Wednesday February 15, 2012 @11:29AM (#39044871)

    GPS was around way before LightSquared's current plan.

    Lightsquared doesn't want to set up a new SatPhone service. They want to use their satellite spectrum for ground-to-ground stations instead. GPS was using their own satellite spectrum LONG before LS decided they wanted to use adjacent spectrum for vastly more powerful (read: interfering) ground service. If all LightSquared wanted to do was set up a SatPhone service, then we would quite correctly be heaping scorn on cheap GPS makers...

    It's not "shitty design" when a GPS cannot block out a tidal wave of signal from an adjacent band, when that band was only supposed to contain a garden-hose sized signal. Yes, equipment must "accept any interference", but not if that interference vastly more powerful than the spectrum was originally supposed to deal with.

  • by Deadstick (535032) on Wednesday February 15, 2012 @11:34AM (#39044917)

    L2 made one big mistake. Stepping on a lot of toes? No biggie, happens all the time. Stepping on toes that are in a building with five sides? Might want to think about that.

  • by rally2xs (1093023) on Wednesday February 15, 2012 @12:33PM (#39045629)

    What's the sense in building a receiver to reject adjacent channel interference that, via an FCC band plan, was never meant to exist? Managing the spectrum so that large amplitude signals are not present is a whale of a lot cheaper than turning a $100 GPS receiver into a $200 GPS receiver when the design and construction of the filtering necessary to reject the supposedly non-existent adjacent channel high power signal causes the doubling of the price.

    If everyone just goes by the band plan, and doesn't try to do some end-run around the intent of the rules, then we can have $100 GPS receivers instead of $200 GPS receivers. I think building them cheaper is the better idea.

  • by sjames (1099) on Wednesday February 15, 2012 @01:22PM (#39046311) Homepage

    I'll bet you're not operating a terrestrial transmitter in a band that is restricted to satellite downlink are you? If you did, you would be shut down, and rightfully so.

    The GPS gear was designed to operate adequately within the environment the FCC promised they would be in. LS begged the FCC to go back on that promise and was given every chance to demonstrate that it wouldn't cause a problem for any existing application. They failed to prove their case. End of story. Note that the FCC was under no obligation to even give them a chance to prove their case, they were entitled to just give them a flat NO.

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