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back to article LightSquared offers low-power olive branch to GPS

LightSquared, the firm which so upset GPS users with their 4G-at-satellite-frequencies plan, has offered to reduce the interference by dialling back the transmission power and clear an exclusive band for precision GPS. The wannabe network operator has already offered to shuffle away from the Global Positioning System, promising …

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Facepalm

"For precision applications, which today use the LightSquared (satellite) signal to augment GPS where high accuracy is needed within the USA (such as guiding tractors and such),"

Forget the tractors, how about also lumping in commercial aircraft guidance in there? LightSquared interfering with GPS navigation isn't going to work very well with the proposed "NextGen" air traffic control system relying almost exclusively on satellite navigation. What's more important, people getting their 4G data connections, or aircraft NOT crashing?

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Bronze badge

@Garry

Sadly I fear the answer is getting their data .

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FAIL

I think LightSquared are trying to pull a fast one, so to speak.

GPS was first. LightSquared are trying to move in and they know they will interfere with GPS yet they are still arrogantly forcing ahead knowing full well what they are doing will cause problems. Plus any attempt to use less power etc for a few years looks like just a cynical ploy to placate opponents to allow LightSquared to get a foothold in the market, then they threaten to will expand to make the their problem worse for others over time.

Also if that isn't bad enough, I can't even see how 4G at satellite frequencies is going to gain wide spread adoption because there will be too many problems with it. So is this just some cynical business ploy by the directors of LightSquared for their company to be bought out by a GPS company, so GPS companies can protect their system from interference from LightSquared? - that's the one angle that would make sense.

Which would make it yet another example of so called Horse Trading (as in unethical business practices). Unfortunately some business people do think like this. They want to cause trouble so they can then offer their solution, which makes them rich.

What LightSquared are doing seems all to dodgy as a business for me to ever risk my money on them. So there's no way I would buy a product from LightSquared knowing the problems its company faces with GPS. I couldn't even rely on LightSquared being around in a few years from now and its not the first communications company I've seen try something then go under and vanish with customers suffering as a result.

I think LightSquared are just trying to pull a fast one so to speak, to intentionally cause trouble, then they will try to be bought out and if that fails, the LightSquared directors will end up giving up and walking off with their rich wages payed for by the LightSquared investors money. The directors can then use the thin argument that the "market conditions were too difficult for success", whilst full well knowing they (the directors) will win big pay whatever happens to LightSquared.

I don't see the directors of LightSquared loosing whatever they do. The only potential looses will be with LightSquared investors and LightSquared customers, so they are not going to get my money.

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WTF?

Ah, the ironies presented by RSS...

This story appeared right next to this one:

http://www.wired.com/dangerroom/2011/09/north-korean-jammer-forces-down-u-s-spy-plane/

Coincidence? I think not...

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@Gary B.

You mean the air planes typically flying at kilometer or more above the ground? You know, a good distance away from the Lightsquared 4G implementation?

Some supplement may be necessary for landing guidance, like ILS and its radio beacons.

So no, this really won't be a problem for the next gen air traffic control systems. Especially since those GPS systems haven't been deployed yet and as such have absolutely no reason not to have sufficient filters.

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I mean the airplanes using GPS as a /replacement/ for ILS/VOR. Besides that, recent reports from testing LightSquared did elsewhere found that interference was generated several MILES from the base station. Even 35,000 feet is only 6 miles.

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Fly by wire

Think of a computer landing the plane, in the fog. These will use precision GPS to position the plane relative to the run way on approach, during the touchdown and taxi it to the runway. There is a university in Germany doing lots of research into the safety aspects of it a the moment.

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Stop

One little thing that is being overlooked here. LightSquared had legally purchased/licensed the allocated bandwidth. The GPS units are NOT designed to use this bandwidth, being licensed to use their own. The US FCC has specifically spelled out the guidelines for this under Part 15:

"This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference and (2) this device must accept any interference received, including interference that may cause undesired operation."

As the "interference" would be occurring not on the licensed bandwidth for the GPS unit but on the section of the spectrum that LightSquared has licensed, GPS clearly falls under sub-section (2) in that it must accept any interference received. As LightSquared is proposing to function in the segment of the spectrum that they have licensed, their signal is not considered interference. If their signal spills over into the GPS portion of the spectrum, then it would be considered interference. However, the complaint here is not that. It is that the GPS units have been using a portion of the spectrum allocated to another use and they do not want to have to filter out the unwanted interference.

The fact that LightSquared is offering to not use a portion of the spectrum they are leasing, and offering to step down their transmission power for what might very well be considered a generation of GPS manufacturing techniques (at greater expense to themselves due to needing many more base stations), shows that they are trying to alleviate the problem. The GPS manufacturers are playing "possession is 9/10 of the law" and refusing to even admit that their equipment is receiving signals on spectrum they are not licensed for.

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One "little" thing you have overlooked, they bought the spectrum and then lobbied to get the use of it CHANGED. If they used the spectrum for satellite use only, there would be NO interference. The FCC should retract their approval to change the use of the spectrum and force LightSquared to use the frequency for what they original bought it for in the beginning.

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Go

Authorized years ago

Actually, LightSquared's planned Auxiliary Terrestrial operation was approved by the FCC years ago, I think 2003. They just didn't use it for a while. So GPS receiver vendors saved a few pence here and there and built units that do not work near the authorized terrestrial transmiters. Now that LightSquared wants to use its licensed frequencies, the GPS industry has its knickers in a twist.

The high-precision GPS signal is separate from the widely-used one. They are willing to pay to move all of those receivers -- there are fewer than a million -- to a different frequency.

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No, I didn't forget

Regardless of the original use, the fact that the receivers are receiving parts of the spectrum they are not licensed to receive is the root of this issue. The receivers are the sticking point. They were built without the necessary filtering because no one was using that portion of the spectrum. So now they're whining because their failure is what is causing this problem.

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Silver badge
Meh

Non-Starter

LightSquared was a lobbying gift to begin with. Laws were changed to give them access to bandwidth that really couldn't be used and everyone knew it. Now that the implications are becoming clear they're offering concessions but at the end of the day they had nothing to offer that would compete with the many uses of GPS by the govt at civilians in the U.S.

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Gold badge

Wouldn't it be funny if...

... the GPS system, paid for by US taxpayers, ended up working everywhere except the US?

What's that you say? Switch it all off? Oh. So it *would* be our problem after all? Bugger!

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Go

Well, even then you'd still have GLONASS, COMPASS and the very beginnings of a GALILEO constellation. And lets face it, its not gonna happen tomorrow.

My guess is that increasingly there will be receivers that can use all four systems to get a position. Hell you could get a combined GPS & GLONASS solution (Ashtech GG24) at least ten years ago.

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Bronze badge

Somebody doesn't know math I believe!

The signal level of "-30dBm" is quite small. In fact is is only a MICROWATT. Yes, one millionth of a watt. I would check the original papers to see exactly what the power level really is.

Yes, GPS receivers are sensitive, but with an interfering transmitter at that level, I suspect it would be easy to filter out. As for Lightspeed, they are trying to barge in on a VERY successful service that our nice (US) government provides (our tax $$$ at work). Unfortunately there is a history of one minded companies taking a prototype with a commonly used frequency and asking our FCC (US equivalent of Ofcom) to grant a waiver for the frequency it wanted to use (I know of two examples). The problem is that these allocations become VERY permanent and after the company who originally wanted the allocation loses interest in the device/function/frequency, they have NO incentive to give back the frequency.

On Part 15: This is only for unintentional transmitters, of which GPS receivers are not. The GPS signal (from space) is properly allocated as a satellite service worldwide.

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Some more math

"-30 dBm is quite small". That all depends on what you compare it to. GPS, for a relevant example, is designed to arrive at the receiver at -135 dBm, making the -30 an overwhelming roar. Of course, the -30 will be attenuated by distance, but close to the transmitter you have a serious problem.

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Re: Somebody doesn't know math I believe!

The lightsquared signal might only be -30dBm but the signal strength of the GPS signals is somewhere around -120dBm, which is a huge difference. The problem is that the lightsquared signal will saturate the input filters of the GPS Rx causing loss of signal.

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Flame

Doesn't that mean the LightSquared will be strong than GPS if its closer than a ratio of 1:160 or basically everywhere under low earth orbit?

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Go

Received power on the ground

The -30 dBm is not the transmitter power of the Lightsquared base station, but the received signal strength, using an isotropic radio, at ground level 50 meters away. Since this is some MHz away from the actual GPS satellite frequencies, a decent receiver should be able to sort them out.

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Black Helicopters

Cheap GPS jammers?

The bigger question is who wants a bunch of low cost devices floating around that are not screwing up GPS only because they haven't been modified by evil people?

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Stop

Break GPS please...

...and make people follow the damn standards.

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Stop

Like starting with LightSquared following the existing "standards" to use the spectrum they bought for satellite-based communications?

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?

I don't follow, last time I was working in the GPS receiver bizz the public part of the system was pritty good at following the standard?

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