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How The FCC Plans To Destroy GPS – A Simple Explanation

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Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#31

Post by winthrowe »

mkr-hn wrote: post #27
winthrowe wrote: post #24

Earlier quoted context omitted.

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.

If you have time, I wouldn't mind some examples. I'm curious, not doubtful. Since this thread sprung up I've wondered what might be impacted by a GPS failure.

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.

http://en.wikipedia.org/wiki/Joint_Stand-Off_Weapon

http://en.wikipedia.org/wiki/Joint_Direct_Attack_Munition

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#32

Post by jbri »

marshray wrote: post #23

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…

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.

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#33

Post by crikli »

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.

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#34

Post by marshray »

jbri wrote: post #32
marshray wrote: post #23

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…

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.

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#35

Post by marshray »

crikli wrote: post #33

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 wh…

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?

http://licensing.fcc.gov/cgi-bin/ws.exe/prod/ib/forms/report...

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#36

Post by icegreentea »

kpeel wrote: post #19
mkr-hn wrote: post #15

Earlier quoted context omitted.

We need someone with air force experience in here. It doesn't seem like they'd let them fly without knowing alternate ways of navigating.

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.

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#37

Post by kpeel »

oomkiller wrote: post #26
kpeel wrote: post #12

Earlier quoted context omitted.

Funny enough, if GPS does get jammed, the USAF has a whole lot of equipment that would be almost useless... Like every modern airplane they own.

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.

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#38

Post by smallblacksun »

kpeel wrote: post #12
oigftrgtyh wrote: post #10

Earlier quoted context omitted.

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.

Funny enough, if GPS does get jammed, the USAF has a whole lot of equipment that would be almost useless... Like every modern airplane they own.

Conveniently, the USAF also has a lot of anti-radiation missiles that are very good at eliminating jamming sources.

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#39

Post by derleth »

riordan wrote: post #4

Meanwhile, the FCC's enforcement chief just put out a press release decrying cell/GPS jammers saying they "create safety risks". http://www.fcc.gov/Daily_Releases/Daily_Business/2011/db0209...

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.)

Re: How The FCC Plans To Destroy GPS – A Simple Explanation

#40

Post by Kadin »

oigftrgtyh wrote: post #10
Kadin wrote: post #9

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 LightSqu…

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.

Yes, the FCC has an enforcement bureau (http://www.fcc.gov/eb/).

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.)

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