LightSquared Says GPS Tests Were Rigged

itwbennett writes "Would-be cellular carrier LightSquared claims that the company's LTE network was set up to fail in GPS interference tests. 'Makers of GPS (Global Positioning System) equipment put old and incomplete GPS receivers in the test so the results would show interference, under the cover of non-disclosure agreements that prevented the public and third parties from analyzing the process,' LightSquared executives said on a conference call with reporters Wednesday morning."

Comments

Really?

[Zeromous]

>old and incomplete GPS receivers

I'm not an expert in the deployment of GPS, but is this not what we would consider a real-world test? Why should they be set up to pass the test, by only testing the latest deployments of GPS?

Don't you test, in order to understand previous unknowns or to flesh out previously unforeseen scenarios?

Re:Really?

[ZaMoose]

They're desperate and in spaghetti-against-the-wall territory, to be honest.

Re:Really?

[Anonymous Coward]

And thank god for that. Forget the millions of drivers for whom GPS is a convenience; LightSquared would spell an end to the major advanced in aviation navigation systems and the accompanying time- and fuel-efficiency gains that have come with it. Check out Canadaian airline WestJet's use of so-called "RNAV" approaches into airports; their use of GPS in those systems saves them millions of dollars in fuel every year, plus gives them and their passengers the benefit of faster trips. No more bouncing around through the 3000 or so VHF Omnidirectional Radio beacons that dot North America.

Re:Really?

[Anonymous Coward]

They are just completely fucked, and I actually feel kind of bad for them. I mean, they theoretically "own" this nice slice of wireless spectrum, which they bought at considerable expense, and they want to do something pretty cool with it, but they're not allowed to because some other industry has been illegally bleeding into their spectrum for years and now it's too late to fix it.

Re:Really?

[CompMD]

It is a real world test. LightSquared has this fantasy that people replace GPS hardware like they do cell phones every two years (or less). There are LOTS of GPS receivers out there that are 10+ years old, and they can't grasp the fact that THOSE WORK FINE.

Re:Really?

[PhxBlue]

Don't be an idiot. GPS receivers don't broadcast -- that's up to the satellites, which transmit timing and location data on two separate bands (three for newer GPS-IIR and IIF satellites).

Re:Really?

[rahvin112]

And they got a steal on the residential parcel and if they can get it rezoned for the skyscraper it's worth 100X what they paid for it. This was nothing more than a gamble to try to get spectrum reallocated to ground prices. They paid almost nothing for spectrum that if it was ground based would be worth almost 6 billion (based on the last auction). The entire reason the spectrum is cheaper is that it costs $2billion minimum to put a satellite in orbit to use it.

Lightsquared is neither innocent nor deserving of sympathy. They were told multiple times the waiver they were given was for testing. It would be foolish of the FCC to not allow them a chance to prove they have developed filtering technology capable of working around the physics. When their testing showed their signal would destroy high precision GPS they had the gall to suggest that the billions of installed GPS receivers have to be replaced that's when they lost all sympathy from me. I have a feeling they've not only known from the begining that this would never work but that they thought they had the political muscle to move it through. Not only that but I don't believe they ever really intended to build a network, but their real intention was to get the spectrum usage switched then sell it 10X what they paid for it.

Re:Really?

[Anonymous Coward]

1 - the LightSquared frequency is actually pretty far from the GPS frequency (10s of MHz), so the filtering challenge is not as bad as you make it out to be.

I did not ignore this fact. As I stated, all time limited signals have mathematically infinite bandwidth. So it doesn't matter how far away on the spectrum one frequency is from another, some part of the signal from the frequency will spill into another.

For quick reference see this: http://en.wikipedia.org/wiki/Bandlimiting

When something like this happens, it's not just about filtering anymore. Filtering only gets rid of the unwanted sideband signals. However, if a larger signal happens to be sitting right around (or pratically on top) the frequency of your signal of interest, there are other issues. There are techniques to recover your signal of interest and the information from it (see channel estimation and forward error correction to start), but it can only work up to a certain point (the larger signal can pretty much entirely swamp out the smaller signal).

2 - Military spec GPS devices have no problems nor do they suffer reduced sensitivity, if someone is already doing it then it definitely can be done.

Military spec GPS devices uses different codes than civilian devices. It is probable that the nature of these codes makes it more robust against interferance (i.e. they were originally designed to be robust against jamming). And can we be certain that these devices won't ever fail under all interfering conditions from LightSquared's network?

Anyways, I haven't seen any of the actual data and test conditions, so I'm not qualified to make a concrete statement about what devices can deal with interferance with LightSquared and under what conditions. I just wanted to illustrate the problem that LightSquared is introducing. This is all without considering that military spec devices are generally more expensive and their implementation is treated at a higher classification level than consumer grade electronics. The hardware/software on military spec GPS devices are all probably covered under ITAR and thus prevent (or at least hinder) manufacturing of critical components outsides the US. If consumer grade GPS were to go under the same scrutiny, I don't think it'll be a while before consumer grade GPS could be affordable to the general public.

Re:Really?

[DeadCatX2]

That depends on your definition of "proper engineering".

Your boss comes up to you and says "Make a GPS receiver". As part of your design, you know you'll need a filter to block signal that's out of the GPS band. So what do you do? Do you make the biggest, baddest filter that you can possibly achieve without regard for expenses?

Or do you analyze the expected power in nearby frequency bands to determine what kind of specification your filter must meet in order to work efficiently without driving up costs unnecessarily?

"Proper engineered devices" would be the ones with the engineer who knows he needs -x dB/octave roll-off in his filter because he knows that the signal in adjacent bands cannot legally exceed y dBm because of the way the FCC has allocated the spectrum. And it is those devices which will get fucked in the ass by Light Squared - all because some engineer actually did his homework.

Fraud, sour grapes, or late complaint?

[davidwr]

If this is fraud on the GPS companies' part or the testing authority's part then there should be hell to pay.

If this is sour grapes then LightSquared just libeled the companies involved.

If, on the other hand, "old and incomplete equipment" tests were a required part of the test for good reason, then LightSquared is a bit late in its complaints - it should've made these complaints well before testing happened, and its current statement should've started off with "As we said before the tests were run, testing for old and incomplete equipment is not a valid test...."

Re:Fraud, sour grapes, or late complaint?

[holmstar]

Of course there's a good reason. Do you really think every GPS device out there is nearly new? There are hundreds of thousands of older devices out there still in use. It would be wrong NOT to test in such a way as to assure that these currently functional devices, which people payed their hard earned money for, continue to work properly.

Big problem with that theory

[Zouden]

What possible motive do the GPS manufacturers have for rigging the tests? If modern, properly-configured GPS units don't recieve interference, then why would they care? I read the article expecting some important link, like Garmin having an alliance with Verizon, but there was no mention of that.

In fact if anything, GPS makers would enjoy selling modern units to customers with older units that no longer work because of LightSquared.

Sorry, but it's just too much of a stretch to believe in this conspiracy. I think LightSquared are simply desperate to get the FTC to give them their waiver. Their business is royally screwed without it.

Re:Big problem with that theory

[HornWumpus]

LTE often called (one of the underlying technolgies) 4G.

I think lightsquared is pissed because they thought they had paid enough bribes and now somebody isn't delivering.

Really? Invalid Test?

[bobbied]

All I can say to LightSquared is ... (sarcasm on) "Right...." (off) This company is *done* unless they can find a way to lower their required power or move their spectrum away from GPS. They are fighting for their very existence and it's getting down to the wire so they are saying *anything* in an attempt to keep things going. The test was rigged eh? Guess physics did you in guys, no need to rig the test. Had you asked an RF engineer you could have saved yourself a pile of cash trying to fight this issue. If the FAA didn't do this idea in because it would make Airborne navigation using GPS unreliable (and thus end the practice), the DOD's arguments should win the day. Further, the FACT that the consumer use of GPS would surely be impacted (if not totally disabled) for miles around their transmitters regardless of what they do should nail the coffin shut. I guess, to be fair, with the FCC buying tickets to the Broadband over Power Lines (BPL) circus, the chance that they'd buy into this sideshow was worth a try. However, the game is over guys.

Wherefore the FCC?

[AB3A]

Missing from the discussion is why this happened to begin with. The Federal Communications Commission was created with the explicit mission to avoid allocation problems like this with the electromagnetic spectrum. This is not the first time they've screwed up like this. In the late 1980s we installed a SCADA sytem on 928.8 MHz. A year after we were up and running, high power paging showed up on 929.03 MHz. You could light a neon bulb with the energy we were getting from our Master receiver antenna.

Our remotes were transmitting with 5 watts and the paging systems were transmitting with over 3 kW ERP. Our receivers had been optimized for sensitivity, not selectivity. But even with the state of the art receivers designed for selectivity, we were still getting clobbered. Only with massive effort did we overcome this problem.

The FCC screwed up because they don't do their homework any more. Even back then, engineers were being relegated to the broom closet while attorneys and political hacks took charge. Applicants were being told to hire consultants to suggest available frequencies, do interference studies and to submit the consultant's work with their license application. Tell me there wasn't a conflict of interest even then!

For all I know things are still like that today. LS probably paid for a consultant who told them what they and the FCC commissioners wanted to hear.

This is why we can't have nice things. We need an FCC to keep this from happening. And instead of an FCC, we get political hacks of both flavors who don't know a damned thing about the state of the art or even what the radio spectrum is.

Re:Who is interfering with whom?

[makomk]

Not really. He portrays it as some kind of heroic battle between some Goliath GPS industry and their army of lobbyists and the poor innocent LightSquared, failing to mention their billions of dollars of backing, or the fact that their own lobbyists were probably the only reason they managed to push this through despite the obvious technical flaws and all the rules designed to prevent exactly the kind of interference they will cause.