This is not an issue. Verizon does not use cheap consumer junk with front ends that are wide as a barn.
The issue is that Lightsquared has paid for bandwidth. They bought it fair and square. They should be able to use it in any way that meets the legal radiation limits for that space.
Now, if you believe that the government can step in and take bandwidth away that has been paid for, and re-purpose it for reasons relating to public service and the common good, that's fine. But if THAT is the case, why haven't most TV radio stations lost their licenses years ago?
Yes, however, since the Reagan administration pretty much gutted the FCC, no real attempt has been made to enforce these regulations. Walk into your local Wal-Mart with a field strength meter and you'll find the vast majority of consumer electronics on sale don't meet the Part 15 rules.
No, they come under either Part 90 or Part 95, since they are deliberate radiators. As long as their out-of-band emissions meet the standard requirements, they are legal and receiving devices have to accept the interference.
That's what the GPS manufacturers are lobbying about. They don't want to have to tighten up their receivers to deal with legal sources on nearby frequencies.
The military receivers have VERY VERY tight specifications for adjacent channel interference, and they also have much more robust lock-in algorithms. The Lightsquared devices will not be a problem with properly-designed receivers, and the mil-spec devices are more than just properly designed.
No, the terrorists already have GPS jamming devices. Hell, you can buy them at truckstops on rt. 95. I occasionally encounter them causing interference with 950 MHz broadcast auxiliary systems.
--scott
- - "C'est un Nagra. C'est suisse, et tres, tres precis."
***** Moderator's Note *****
Why would truckers want GPS jamming devices? Devices to jam police radar, I can understand, but not GPS.
Nor does the military, but the Air Force General in charge of GPS said it won't work.
Wrong: they bought an insolvent company with rights to use a SATELLITE band for SATELLITE reception, and are trying to bribe Congress to let them use the SATELLITE channels for ground-based communications.
First, it's not paid for: it's licensed. The FCC issues licenses to those firms who win spectrum auctions, provided that those firms _ALSO_ meet the requirements for a license in the band being applied for.
Second, the LICENSE issued to SkyTerra was for transmission *FROM* a satellite *TO* ground stations, *NOT* from ground stations to other ground stations.
And, third, the government *CAN* step in and take bandwidth away and "re-purpose it for reasons related to public service and the common good". The Class C and D Citizens Radio Service assignments at 27 MHz are in what used to be a 11-meter Amateur band. There is ample precedent for the FCC reallocating spectrum.
The reasons that "TV radio stations" don't lose their licenses aren't important to this discussion, except as they relate to the spineless nature of our current Congress and its willingness to sell their souls and our future for chump change.
Most of the trucking companies have gadgets on board the trailers so that the trailers radio their GPS position back home. This allows them to track containers, but it also allows them to check how fast the driver is going, how much time he's spending on breaks, whether he's goofing off, etc. Drivers don't like this, so they buy small jammers which are broadband noise sources that knock out all kinds of adjacent services.
Sure, it's illegal, but so are the 10 watt long-range cordless phones that they sell at the flea markets. The FCC has no money to actually enforce the rules.
Agreed, the complexity of keeping a single Geosynchronous satellite on station is hard enough (and when the fuel runs out and it drifts out of the assigned antenna window, well there's another piece of space junk to deal with), let alone a LEO constellation that probably depends on precise positioning of all the birds for the basic functionality of the system.
Actually, does anyone know if they use the last bit of fuel in a satellite to send it on a "death spiral" to eventually burn up and clear the sky of that particular piece of junk?
See what happened to Television channel '1', or the UHF channels 70-83. Also channel 37. And what is currently happening to TV channels 52-69.
Not to mention that TV station licenses _have_ been revoked in the past. I don't have the specifics to hand, but there have been 'more than one' such instance.
***** Moderator's Note *****
Oh, yes: I forgot to point out that SkyTerra didn't "buy" the spectrum at anything near the going rate: they got some low-rent SATELLITE spectrum, never paid to orbit the required SATELLITE, and were bought out by an avaricious gambler who wants his going-downhill-fast hedge fund to profit beyond the dreams of Croesus by ruining the GPS system for everyone.
All in a day's work, by the standards of Capitol Hill: I bet he figures that when the bill comes due and a few lightplanes crash and common people like me have to buy new, improved GPS receivers to compensate for his greed, he'll be a both richer and gone.
They definitely do that for geostationary satellites, as the geostationary orbital slots are a limited resource.
Wikipedia for "disposal orbit" - says they don't try to drop the satellite *down* into a burn-up orbit (probably requires too much delta-V and thus fuel) but instead boost it *upwards* into a higher, non-geostationary orbit.
I'm not sure what they do with GPS satellites... these are in much lower orbits and it might be feasible to drop them into a lower-altitude "enters atmosphere and burns up within a few decades" orbit.
In snipped-for-privacy@host122.r-bonomi.com (Robert Bonomi) writes: [snip]
Keep in mind that the military mindset for matters of this sort doesn't look at the "likely" problems, but gets concerned (more or less justifiable so) with the absolute worst case, even if highly unlikely, possibilities. So yes, the general is concerned.
It's kind of like... the folk who tell the villagers there's no need to keep banging drums to scare away the dragon that's eating up the sun during a solar eclipse...
Chances are there's no issue, but... what if there is...?
Keep in mind that the post-"W" political mindset for matters of this sort gets concerned (very justifiably so) with the absolute worst case possibilities. So, yes, I'm concerned: this looks to me like a sellout on a national scale, started by a deep pockets financier who is willing to endanger lives and ignore the expert opinions expressed by disciplined professionals who cannot gain anything, and might lose their jobs, by telling the truth.
There are millions of GPS location transponders that keep track of the location, speed, and arrival times of semi-trailers, freight cars on trains, and utility vans used by every major corporation from telephone companies to package delivery services.
That's not to mention the millions of consumers who have purchased GPS devices, smart phone "Aps", and GPS-enabled cellphones, all of which are affected by this sellout. I don't pretend that my Garmin GPS going dark is going to shake the earth or endanger my life: it will be an inconvenience that forces me to start printing trip routes from Google maps again. However, much of the E911 system's ability to track the location of persons in distress depends on GPS receivers which are installed in exactly the same class of devices that LightSquared's power grab will render useless in emergencies.
Of course, there are more immediate, more likely threats: such as the danger for thousands of General Aviation aircraft with GPS navigation equipment. If _those_ go dark, so may the pilots and passengers who depend on them.
General Aviation isn't high-budget military flying - it's people and planes that extend from restored Piper Cubs to multi-engine turboprops carrying both road warriers and vacationers from "spoke" airports to regional hubs, and they all depend on GPS to navigate safely to "off airways" locations and secondary fields which don't have the dedicated navigational aids present at major airports. In short, compromising the GPS system will kill more people every year than every firearm in every nut's hands, but politicians seem to be willing to pry GPS from the cold, dead fingers of aircraft pilots and passengers who did nothing more onerous than believe it would work as the government promised.
LightSquared's future is on one end of a political see-saw that has at its other extreme an entire system of navigation designed and implemented over decades, and nobody on Pennsylvania Avenue seems to care.
It's kind of like ... the little voice in the back of my head that says "Not him: I can't believe that Barack Obama would turn into the kind of politician he was elected to replace". "Oh, it can't be", the voice tells me, "please don't let him turn out to be for sale like his predecessor, that vote-for-anyone-but-him vicious, snarky, spoiled rich kid".
Chances are there's no issue, but ... if there is, then the Democratic party is dead for the next thirty years. If the President is a participant, then this is right up there with Watergate. If he's allowing it to go forward because he's unaware, then it's right up there with Teapot Dome. Either way, or anything in between, President Obama bears the blame.
Hate to tell you this, but that's not exclusively a satellite allocation there. Check the FCC frequency allocations. Satellite use is primary but not exclusive (much like that slice at 138 MC).
No, and that's basically the problem. This has been turned into a political football by nontechnical people who don't understand the issues, and you're buying right into it.
Not necessarily. It would be nice if our military's general officers were always concerned with the nation's best interests, but recall that many "retire" before they're too old to work, and they tend to get high-paying jobs in private industry. Why would a Pentagon politician be much different from a Capitol Hill one? And, as Danny Burstein noted,
El Moderador noted,
Not really. ATC (ancillary terresterial component) goes back a long way. I have personal knowledge of efforts to get ATC approved, so that satellite vendors could lease spectrum to terrestrial cellular-like operators, well before 2003, which is when I think SkyTerra (now called LightSquared) got its ATC approved. SkyTerra (originally called Mobile Satellite Ventures) has put up satellites; like other mobile-sat vendors, its business has been slow due to widespread availability of terrestrial cellular service. So it's mostly used by transportation, public safety and other industries that require widespread coverage.
The big change has been to allow ATC to be used on handsets without satellite capabilities. Satphone-only ATC has not been deployed much, so the GPS receivers didn't have to deal with it. Now they're essentially repurposing the band for dual use, providing more terrestrial capability.
GPS operates on multiple bands. The encrypted military stuff runs on lower frequencies (I think around 1200 MHz) than the civilian one in question here (which starts at 1557, right above LightSquare's upper band). The high-precision stuff uses a third signal, from either LightSquared's or Inmarsat's satellites, and the former would be clobbered by the planned ATC. Since only a fairly small number of receivers use the high-precision signal (mostly for farming and mining, not urban areas), LightSquared has offered to retune all of the ones on their frequencies (for around $400M) to shift to a different frequency.
Bear in mind that LightSquared has two bands, the lower one around
1510, the upper one around 1547-1557. The 2003 ATC license grant was for both, and they had planned to use them. But because GPS became more common since then and with some really crappy receivers that simply assumed that there'd never be ATC, they've since offered to not use the upper band for a few years, giving time for most of the crappiest receivers to die of their own accord.
If the mobile GPS receivers have barn door front ends, then they'll briefly lose signal when passing a LightSquared tower, once LightSquared opens its upper band. But they won't make the systems useless; real trucks and trains move a lot farther than the blanket-interference zone of a tower. The lower band won't harm even a bottom-end receiver.
Not if the lower band is the only one used. Your typical cell phone has a useful life of 2-3 years, so if they don't turn on upper band for 3 years, this gives cell phone makers plenty of notice. But again the impact would be very localized.
Probably not. Cell phone E911 is assisted GPS, getting part of the coordinates from the cell towers, and again only the upper band has any impact, so it's a at least few years off.
Your risk is greatly exaggerated. Same issue -- only if upper band is activated, and only near a tower. Planes rarely fly close to towers at low altitudes -- it's not safe -- and when they're above them, the signal going towards the plan will be weak, because cell antennas have narrow vertical plane patterns, generally with a downward beam tilt. So it might focus its signal from say -1 degrees to -11 degrees downwards, and thus an airplane above it would never intersect the strong-signal pancake (really a cone). Of course I would not really want aviation GPS to have barn door front ends anyway.
ATC was approved during the Bush years. What you have are makers of GPS receivers looking to save a few pennies by externalizing the cost of bad receivers.
We had a similar power play pulled in Congress a decade ago when the FCC first authorized low power FM. The new rules initially got rid of third-adjacent channel protection, so that an LPFM station could be 600 kHz away from another FM station. The old rules dated back to the 1950s, when "IF cans" were the norm, not ceramic filters, and even then they were overly strict. However, the NAB didn't want more competition, so they used their clout to limit LPFM, a law finally repealed last year. In the interim, though, China shipped over a lot of FM receivers, all implemented on one chip, selling for under $2 (often given away as convention or holiday favors and the like). These are indeed broad as a barn door. So are most hotel clock radios. But that's their fault. We can't waste good spectrum just because a few cheap receivers really stink. If LightSquared does get permission to follow its revised plan (low band now, high band in a few years), vendors will first cry, but then will miraculously discover that making better receivers only costs a tiny bit after all.
Primer on receiver overload: A receiver is prone to out-of-band signal overload for a few reasons.
- Front end intermodulation. If the initial amplifier or (more often) mixer in a receiver is not properly linear, then out-of-band strong signals will mix together and block desired signals. Integrated circuit mixers are not the best here; discrete circuits work better. JFETs work better than junction transistors too.
- Front end desensitization. Even if the out-of-band signals don't show up in the wrong place, the sensitivity of a receiver can be impacted by a strong signal out of band. This could be caused by insufficient local oscillator injection, a crappy mixer, or other design flaws, most of which cost a little to fix, which is why they're the norm.
- Phase noise. A frequency synthesizer is used to create the tuning local oscillator signal, and cheap (one-chip) synthesizers don't create clean sine waves. When you mix a noisy signal with the desired signal, you get a noisy output. Low-noise synthesizers are of course a bit costlier to build than high-noise ones.
- Filters. You can filter unwanted frequnencies, but again it requires a little bit of hardware.
So the drive to build the cheapest plausible product has lowered the quality of mass-market electronics, including GPS receivers. In the very deregulatory US, we don't have laws that require testing of most products to see that they meet some kind of minimum standard. So China ships us their worst.
-- Fred Goldstein k1io fgoldstein "at" ionary.com ionary Consulting
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