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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

#41

Post by X-Istence »

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…

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?

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

#42

Post by X-Istence »

marshray wrote: post #34
jbri wrote: post #32

Earlier quoted context omitted.

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.

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

#43

Post by X-Istence »

derleth wrote: post #39
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…

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.

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

#44

Post by Kadin »

aj700 wrote: post #22
mkr-hn wrote: post #18

Earlier quoted context omitted.

It's obvious now that I think about it. Even with GPS, they're going to be told landmarks and indicators (roads and stuff) during a briefing.

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.

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

#45

Post by X-Istence »

wickedchicken wrote: post #28

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.

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

#46

Post by crikli »

marshray wrote: post #35
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...

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.

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

#47

Post by btilly »

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…

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.

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

#48

Post by georgecmu »

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…

I find the GPS World publication [1] on this subject a lot less alarmist and better balanced.

[1] http://www.gpsworld.com/gnss-system/news/data-shows-disastro...

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

#49

Post by crikli »

X-Istence wrote: post #41
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…

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…

I scanned the article, rushed to judgement about the context, and totally missed that part.

Basically I was that guy on the internet I complain about.

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