Ugh, c'mon, people. The FCC isn't planning to destroy GPS. I hate the FCC as much as the next guy on the Internet, but that's too ridiculous for consideration.
What they're trying to do is balance the legitimate right that one user has to a piece of spectrum, with the legitimate right that a lot of users have to some that's adjacent. They'd be looking at nothing but an endless series of lawsuits if they told LightSquared that they couldn't use their spectrum (which they have a license to), particularly since LightSquared has a proposal which -- yes, on paper, but what's on paper matters -- says they'll not interfere with GPS.
It looks much more like the FCC is giving LightSquared an opportunity, either to show that they can make the system workable, or to come up with enough rope to hang themselves, one way or the other. If LightSquared can't resolve the interference issues, then the FCC will have a much better case for an enforcement action than they currently do. (Although an enforcement action might require a rule change, because it's not clear that they would actually be in violation of the rules; front-end overload is typically the receiver's problem, not the transmitter's.)
I'm all for spectrum users being vigilant, and perhaps GPS users need an organization analogous to the ARRL (which protects the Amateur Radio spectrum, and successfully defeated the shitty BPL implementations that were kicking around a few years ago) to nip these things in the bud. But the conspiracy-theorizing is a bit rich.
If all that they're doing is trying to "balance the legitimate right", then why aren't they following all of their standard procedures before granting access? The mere fact that they have not followed standard procedures is pretty good evidence that LightSquared is getting special treatment.
Has the FCC ever bothered to actually go after people that abuse bits of the spectrum? Wardrobe malfunctions they are right on top of - but anything that requires technical knowledge seems to escape them.
GPS does have a group that protects it's users - I believe it's called the USAF.
A few years ago the FCC showed up at a coworker's house with their van. Something in his house was emitting improperly. They eventually tracked it down to a computer monitor.
So there are enforcement people out there. They just don't happen in the middle of a superbowl broadcast.
They unfortunately do not have nearly enough officers to really do anything particularly effective, but if you are really egregiously bad about your spectrum abuse, to the point where you generate complaints from other users, they do sometimes pull licenses.
The only interaction with them I have any sort of knowledge of is secondhand; a friend of mine spent months trying to get the local power company to fix a bad transformer on the street that was failing internally and creating a lot of noise, pretty much from DC well up into the HF. (And I suspect it was making some pretty ugly AC waveforms.) They wouldn't do anything, and he eventually got one of the FCC Enforcement Bureau people involved.
You have to be a very "squeaky wheel" to get any sort of attention to a complaint, though; my friend had what amounted to a fairly serious engineering study of the failing transformer, done with parabolic antennas and spectrum analyzers, so that the FCC guy didn't really have to do a whole lot. (Presumably he verified things, but I don't know for sure.)
A few years back, a local WISP (in Montana) was shutdown because they were breaking the Part 15 power rule in several markets. Their custom made radios were putting out over 5 watts EIRP, when the maximum legal limit is 1 watt. It took the FCC several years to get out here, but they did do it.
Actually most modern munitions are guided by inertial navigation, mainly so targets can't jam them. Aircraft etc also have this capability. They have known about the risk of jamming since the beginning, so surely they've prepared for it.
Very true. My answer was a bit tounge-in-cheek, I just didn't get it across properly. While losing GPS would be a problem, it certainly wouldn't bring down our military.
This specific problem definitely wouldn't affect our aircraft simply because they would be at such a high altitude. Even if it was a problem, the military also has a some pretty impressive anti-jamming capability.
I'm not actually air force, but am a bit of an aviation buff with a private license. There would be backup nav systems in manned aircraft, but several popular modern munitions are GPS guided, and I would tend to think that modern battlespace information systems require it as well. Planes wouldn't fall out of the sky, but it would be a significant departure from the ideal state.
Of the munitions? I hear JSOWs and especially JDAMs are popular recently.
As far as BIS info, it's not something I've followed closely, but we're talking things like every plane, tank, and infantryman now (soon?) has gps and information on the location of all friendly forces is automatically shared so you cut down friendly fire.
Apparently caf has more info on milspec GPS than I do, I thought that it required the same main band as civilian, and just used additional military bands to increase precision, but apparently it can function fully independently (not really surprising when you think about it). At least that gives you a little info on some of the troubles of failure of military GPS, as unlikely as that is.
Why shouldn't this break military plane GPS as much as anything else. It will also remove the ability of USAF to GPS target missiles onto US population centres, which they have no need to do anyway. They can still bomb the rest of the world no problem.
Military GPS receivers operate on two carrier frequencies, only one of which is used by most civilian models. (And it's the shared military/civilian frequency which is adjacent to the spectrum in question.)
Using two frequencies makes the military receivers more robust, and also lets them do some clever ionospheric distortion cancellation that you can't do with one channel. (Basically they get the benefits of WAAS without actually needing to receive the WAAS signal.)
That said, neither the FAA or the military are going to tolerate any significant degradation of GPS, domestically or otherwise.
Yeah, I was joking a little. Most aircraft would still work pretty well off of inertial data. However there are quite a few weapons systems that just plain won't work without GPS.
BTW, I'm not a pilot, but I work for a government aerospace contractor, so I have some experience in this.
I thought the most common ones (JDAMs) still had an inertial navigation system cause GPS/INS is used nearly everywhere. It'll probably have horrible accuracy (I guess that depends on how the coordinates sent to the bomb are handled... if it can be calculated as an offset of what the INS thinks it is, then it wouldn't be that bad). But still better then unguided bombs.
While an interesting article which does a good job of breaking down the technical details AND citing industry, it doesn't seem to me the FCC is "Planning to destroy GPS".
This sounds a lot more like the FCC not entirely understanding the ramifications of what they approved and/or a company trying to take advantage of licensing loopholes which have unforeseen consequences.
Yes, the FCC fucked up here but it isn't time to bring out the tin foil hats yet.
Not at all. It's like the FDA approving a drug with a 100 mg /day dose, and a company rolling out a plan for 200 mg /day dose, and trying to convince the FDA that 200 mg is safe. Unless they actually get approval for 200 mg, they're not going to be able to ship.
And continuing the metaphor: having the FDA say "If your self-funded trials say it's Ok, then we're satisfied".
The funny part is, some times, that's how the FDA does work. That's how we wound up with all those depression drugs that were only as effective as a placebo.
I'm a licensed (technically "certificated") private pilot and this is article is bullocks.
Aviation, both general and commercial, relies increasingly on GPS integrated avionics to navigate the rigidly defined airspace that instrument rated pilots refer to as "the system."
GPS has become so prevalent that the decades old method of navigation using VOR (VHF omnidirectional frequency) radials is going the way of that which came before it, ADF ("Automatic" Direction Finder).
Even the smelly old 1965 Piper Cherokee I fly sometimes has a Garmin GPS unit in it. The guy that taught me to fly has a 1947 Cessna 140 with a GPS unit. It's become ubiquitous in general aviation and is a de-facto requirement in commercial aviation.
GPS isn't going anywhere because it's too crucial to one of the major facets of the national transportation system.
Perhaps you can explain why the FCC is granting this license/waiver even in the face of vehement opposition from a broad collection of GPS manufacturers and aviation groups?
The opposition was vehement, yes, but limited to strongly worded letters from (mostly) small general aviation companies. No Boeings, no American Airlines, no 'big guns' with be-suited lawyers to make the FCC wake up and smell the jet fuel.
Wait until a couple airliners go missed on RNAV GPS approaches in low IFR conditions (visibility < 1 mile or cloud ceilings at less than 500 feet). The airlines will raise hell, the FAA will get involved and that'll be all she wrote.
I think this company is a customer of Boeing's. Boeing builds their satellites.
As for the airlines, they are so heavily regulated that they might think twice about filing official comments on stuff like this without permission. No doubt FAA and FCC are talking about this even if it's not official. Their offices are only a few blocks away.
What about this article is bullocks? Would you please elaborate on it? The only thing for aviation is:
"The results are even worse for the aviation GPS. The FAA has essentially discontinued support for the old LORAN electronic navigation system in favor of GPS, and now LightSquared has proposed a system that essentially disables GPS in exactly the areas aviation needs it most."
The author is agreeing with you in that it would be a disaster for both commercial and non-commercial.
Was the article modified since you posted your comment?
Well, they do: Doctors and other medical professionals have come to rely on cell phones to be notified of emergencies quickly enough to save lives. If they are blocked, there's a realistic chance lives will be lost for no good reason.
(I've never heard of a good reason to block cell phone transmissions. It always seems to come down to trying to enforce some vision of politeness via technical means, which doesn't take considerate cell phone usage into account at all.)
This is why it should be possible for theatres and the like to set up alternate base stations that cell phones connect to, this way 911 calls and text messages incoming may still be delivered but no incoming/outgoing calls may be connected.
In the scenario I'm describing, the doctor is going to the theater when they get a call from the hospital saying there's someone there who needs their skill. (It's actually in their contract that, while they're on-call, they have to remain within a certain amount of travel time from the hospital so they can get there in time. This does affect home purchases.) If their cell phone is blocked, the call is missed and someone may very well die.
You could (presumably) attempt to fix this with technology. It might even work for a while, but when it breaks, someone could very easily die. And they'd have died of someone else's dislike for cell phones, which is not a good reason.
(sigh) The article was written by an alarmist moron trying to push his own agenda, and most likely, pushing it for his own profit.
The only real problem is GPS equipment manufacturers intentionally cut corners and costs by FAILING to implement proper bandpass filters.
When the LightSquared towers get turned on, and customers who bought incorrectly designed garbage from the likes of Garmin, the result will be simple: The equipment makers will get sued in massive class action law suits for selling broken equipment. And yes, the manufacturers deserved to be sued for cutting corners on bandpass filters and selling junk since THEY HAVE ALWAYS KNOWN the adjacent spectrum frequencies could be used at any time.
It's possible the LightSquared transmitters will be far more directional than the Garmin test gives them credit for. They may not run full power all the time anyway.
Regardless, it's generally the responsibility of the receiver to ignore signals in another part of the same band, and this is a different band entirely. Perhaps some receivers are built as cheaply as possible and don't have the best filters. If they all break, well, their customers should know not to trust that brand again. Any other policy amounts to no one ever being able to establish new radio service on its own part of the spectrum, on the theory that some other defective other equipment might fall over.
Personally, I think it's far more interesting the prospect of having a network of 20,000 steerable-beam transmitters approved for 15KW ERP each at 1.5GHz. 300MW is about half the output of a typical electrical power plant. If those were networked that could make one hell of an antisatellite weapon, phased-array radar illuminator, or maybe even an SDI-type directed energy weapon.
If the military isn't behind this, well they should be. <conspiracy theory>Maybe that's why the FCC is fast tracking it so much.</conspiracy theory>
It's the responsibility of the receiver to ignore signals transmitted at appropriate power levels, yes.
The receiver is not required to be overengineered to cope with transmissions vastly more powerful than expected - that's why limits on broadcast power exist in the first place.
OK I see it now. It looks like everything in that adjacent band had previously been designated space-to-earth.
I suppose it would be reasonable for an engineer to assume a receiver is not going to end up within a few KM of a 15 KW transmitter at those frequencies.
At high power you can overpower adjacent frequencies wether you have good band filtering on it or not. For example a 2 Watt FM transmitter at 100 Mhz can easily overpower radio's tuned to 95 Mhz just because of its power, even with the appropriate filtering.
The internationally-agreed upon plan for the adjacent band was to have all the transmitters in orbit and all the receivers on the ground. So I don't think a 2W transmitter in orbit is going to overpower receivers in a different band.
40,000 of 15KW transmitters on the ground may be another matter.
Why would the military want an array of tens of thousands of low-power emitters when a few klystrons will do? 10+ megawatts pulsed output in a single L-band device is not hard to achieve, and much higher can be achieved if you're willing to accept the higher cost and shorter lifespans associated with running at higher voltages.
1. They can repurpose existing infrastructure with just a software change
2. Nobody has to pay for much out of their own budget or build it in anyone's back yard
3. Nobody has to declare it under any treaties or such
4. The system can receive as well as transmit
5. It's engineered and tested for continuous operation. There may even be excess capacity available almost for free
6. The system is massively redundant and supplies its own power and backup generators
7. More is better
8. Why not?
9. If it saves one child...
10. ...
11. Profit!
and so on. Just tossing out wild ideas here.
If only Nikola Tesla were alive to see this plan, he would certainly approve.
Yes - without it's operation many senior members of staff would be forced to learn map reading to find their way around Washington (or at least their drivers would)
Galileo changed the frequency to be slightly different to GPS to allow selectively blocking one or the other - but it's still close enough for this to interfere.
I thought GPS was spread spectrum which would make it resistant to these kinds of interference? After all, GPS satellites broadcast at the same frequency as each other, that's the genius of how GPS works.
By the time the GPS signal reaches earth it is at a very low power, think milliwatts.
Lets think of it as you trying to eavesdrop on a meeting.
You have your ear pressed on a big thick wooden door that lets very little sound through, you are attempting to hear so you have everything around you very quiet and try your best to hear that very faint sound of your boss talking about the companies plan to fire everyone. Now your co-worker just a cubicle down is on the phone and instead of keeping it down is talking very loudly. It doesn't matter how hard you try to listen for the sound from inside the meeting all you can hear is your co-worker.
Now think of your boss in the meeting as the GPS satellites and your co-worker as this new company.
Unfortunately when it comes to transmitting power, the more you have of it the more likely you are to overpower other signals. This is the same issue that FM transmitters have as mentioned in the article.
Unless we put better band filters on GPS devices and attempt to filter out a very high power signal GPS is going to get lost in the signal that is being transmitted from the ground.
GPS signal strength at Earth's surface is -130dBmW, so that'd be attowatts... A GPS satellite capable of 0dBmW would be truly scary; it'd have about a petawatt of electrical supply.
What they're trying to do is balance the legitimate right that one user has to a piece of spectrum, with the legitimate right that a lot of users have to some that's adjacent. They'd be looking at nothing but an endless series of lawsuits if they told LightSquared that they couldn't use their spectrum (which they have a license to), particularly since LightSquared has a proposal which -- yes, on paper, but what's on paper matters -- says they'll not interfere with GPS.
It looks much more like the FCC is giving LightSquared an opportunity, either to show that they can make the system workable, or to come up with enough rope to hang themselves, one way or the other. If LightSquared can't resolve the interference issues, then the FCC will have a much better case for an enforcement action than they currently do. (Although an enforcement action might require a rule change, because it's not clear that they would actually be in violation of the rules; front-end overload is typically the receiver's problem, not the transmitter's.)
I'm all for spectrum users being vigilant, and perhaps GPS users need an organization analogous to the ARRL (which protects the Amateur Radio spectrum, and successfully defeated the shitty BPL implementations that were kicking around a few years ago) to nip these things in the bud. But the conspiracy-theorizing is a bit rich.