LightSquared Disrupts 75% of GPS Connections In Government Test

Freddybear writes with this quote from BusinessWeek: "Philip Falcone's proposed LightSquared Inc. wireless service caused interference to 75 percent of global-positioning system receivers examined in a U.S. government test, according to a draft summary of results. ... The tests worked off an 'extraordinarily conservative' threshold and didn't show the devices' performance was affected, [LightSquared exec Martin Harriman said]. 'If we're affecting the performance of the device — my goodness, we'd like to be sure that doesn't happen,' Harriman said. The laboratory testing was performed for the National Space-Based Positioning, Navigation, and Timing Systems Engineering Forum, an executive branch body that helps advise policy makers on issues around GPS. It found that 69 of 92, or 75 percent, of receivers tested 'experienced harmful interference' at the equivalent of 100 meters (109 yards) from a LightSquared base station."

Comments

This is being whitewashed from the white house

[SuperKendall]

This story is bad enough until you find out the white house was pressuring people to hide issues related to LightSquared.

And Philip Falcone is a huge donor for the Democratic Party.

I'm not saying Republicans are angles or anything like that. I am saying this a very bad case of corporate ties directly to the whitehouse that is threatening to disrupt a major technology just to make some money...

Re:This is being whitewashed from the white house

[LtGordon]

I'm not saying Republicans are angles or anything like that.

You could, however, say they are quite obtuse.

Re:This is being whitewashed from the white house

[Shadowruni]

But the Republicans are Right (angles)! Thank you ladies and gentlemen I'll be here all week. Try the fish!

Re:This is being whitewashed from the white house

[Anonymous Coward]

You forgot to mention that Phillip Falcone is under investigation by the SEC.

Re:This is being whitewashed from the white house

[Anonymous Coward]

I'm an electrical engineer. I did my doctorate in a GPS lab working on safety-of-life applications (landing planes and such). The LS issue has been a very hot topic of discussion in the technical community for most of the past year. At the annual ION GNSS conference this past September, there was a panel discussion on the preliminary test results described in TFA. Out of approximately 600 people in the room, there were exactly two who expressed opinions supporting LS's contention that the interference to GPS would be insignificant: one guy was the LS General Counsel, and the other was a guy who is claiming he has retrofit kits (RF notch filters) that will eliminate the interference. It should be noted that, when asked how his kits would be fitted to the millions of GPS receivers already in the field, the latter person had absolutely no answer.

It is not at all a stretch to say that very nearly 100% of the people who have done LS testing, or evaluated the results from an engineering perspective, conclude that the effects as proposed will be somewhere between "significant" and "catastrophic."

--Jake

Re:This is being whitewashed from the white house

[Megane]

It's not that they're using "cheap parts". It's that the signal from those little solar-powered tin cans whizzing around in the sky is so weak that adding a notch filter to increase selectivity would significantly affect the ability to receive the signal at all. And they want to drop this elephant right next to it.

But hey, they paid their donations to the Party, right?

Re:This is being whitewashed from the white house

[vlm]

The nearest GPS freq is 1575.42 MHz but is the L1 freq

Very close but not quite. The L1C signal is not a simple continuous carrier like the old transit sats from the 50s/60s. The data rate is somewhere around ten megabits and it modulation is BPSK. The exact answer requires more detail but the actual transmitted BW will end up maybe 10 megs higher and 10 megs lower than the center theoretical carrier. Which is getting uncomfortably close to the lightsquared signal.

So... that's 1565 or so, vs the interference at 1559. So you head over to minicircuits.com (a seller of many microwave components, including the high pass filter you are trying to purchase) and look for a coaxial filter with a curve showing almost 0 dB attenuation at 1565 and up to keep your noise figure usable, and at least 60 dB out of band attenuation at 1559. Then you realize why the EE types claim "its a law of physics" that this simply cannot be worked around. Oh and note the ones that don't even come close to making the grade are roughly the size weight and cost of a very small cell phone. Generically building a filter in that frequency range with those specs is impossible, but building the device to that exact frequency spec and stable over any temperature range makes it even more impossible.

Before the sorta knowledgeable DSP types jump in, yes, you can get filter curves like that using DSP. However you need a analog input clean enough to do the DSP on it... So, again, you're screwed. Just plug your 60 dBm 3rd order IMD preamp into your 32 bit A/D 10 GHz A/D converter and then process it. This is technobable of the finest level, components with specs like that Might exist in just 50 years or so, but they sure don't now.

Re:This is being whitewashed from the white house

[Anonymous Coward]

Run the numbers on the Q factor required and the maximum possible passband attenuation to keep the noise figure of the front end usable... If you know what "snake oil" is WRT crypto it sounds like this guy's offering sounds suspiciously like "frequency grease" WRT RF.

Note that if the problem is front end overload, his snakeoil/freqgrease might be a simple 10 dB attenuator, probably being sold at an immense markup. If would be easier to duct tape aluminum foil to the existing antenna until the incoming signals are knocked down enough that the FE is not overloading but optimistically there is still enough RF signal left to decode.

This is assuming its not at the RF technology level of those stickers you put on cell phones to magically do things that sound good.

I am intimately familiar with the RF arguments. The proposed notch filter is indeed snake oil, but not for reasons of insufficiently steep stopband rolloff. Rather, it's a relatively bulky thing which will work just fine for the receivers produced by the guy's company (Javad), and maybe even other receivers that could be retrofitted. But it is totally unusable for most embedded receivers (handhelds, etc.) due to size (and cost), and there are a lot more of those deployed in the world. The "snake oil" part of the argument is that he is being spectacularly disingenuous about it: when asked how he intends to retrofit every TomTom, Garmin, GPS-enabled wristwatch, and mobile phone already out there in the field, he just waves his hands and says, "those devices won't be affected."

While I'm on the subject, people seem to be unaware of a further bit of deception on LS's part. Their initial proposal included two bands just below GPS (the so-called "Low 10" and "High 10"). When testing showed that the resulting interference would make the proposal a non-starter, LS submitted a modified proposal in which they would only the lower of the two bands (farther away from GPS), and at a lower broadcast power level. The thing is, LS never stated that this was their intended final configuration. Indeed, upon further discussion, it emerged that this revised proposal was intended only to placate objections in the short term, and that LS fully intends to use both bands and the higher power levels (as in their original proposal) eventually. In other words, the potential interference problem was never addressed, just kicked down the road a bit.

In short, the proposed filter was far more sophisticated than the bits of aluminum foil you might see for sale on QVC on channel 179 at three in the morning... but it's virtually meaningless in any practical sense.

You don't understand how this works do you.

[SuperKendall]

Solyndria (another company propped up by the white house despite many reports saying the company was not financial viable) was given a ton of money, which the founders (also heavy donors to the Democratic party) got a lot of, then the company went bankrupt but they left with a few million dollar paychecks.

It doesn't matter if the company folds. Just that Philip Falcone makes money in the process, which he will.

More Context

[Anonymous Coward]

This came out during the week, but was overshadowed by the news that Falcone And Friends got Wells Letters, SEC notices that are basically game-over. Investors in Harbinger Capital Partners, Falcone's hedge fund, are likely to flee, but they'll be limited in their ability to withdraw funds. This has happened before to Harbinger in 2009, and Goldman Sachs seems to have gotten preferential treatment in exiting.

The LightSquared bit is juicier, though, because of the hints of corruption that have squeaked out through the press. Air Force General William Shelton, testifying before Congress about LightSquared and the interference that its plans could cause GPS, complained that the White House had told him to change his testimony to make it seem that he was less opposed to LightSquared's plans. There are also allegations of $30,400 donations being given to the Democratic Party by Falcone and LightSquared's CEO on the days of meetings and on days when meetings were arranged.

Re:Farm GPS, airplanes, and who owns the bandwidth

[jchernia]

Yes, but the towers are broadcasting signals that are orders of magnitude more powerful to ground receivers than the gps satellites. If Lightspeed was a satellite phone system (so if it was another satellite system producing the crosstalk), it would not interfere even if the frequencies were directly adjacent.

Re:Farm GPS, airplanes, and who owns the bandwidth

[Anonymous Coward]

I'm not an expert, but read some back issues of GPS World. Lightsquared is doing dastardly deeds - this frequency was never intended for terrestrial broadcasting. They pulled a fast one and got this for a steal. The FCC screwed up big time - either incompetence or someone was asked to do a favor or paid off. There's a lot of FUD - Lightsquared has been planting stories claiming that the GPS devices won't work do to shoddy engineering. The facts are that they should be building terrestrial base stations that broadcast near GPS frequencies and not have to at least go through a thorough review and pay what this spectrum is really worth.

You don't see consumer electronics or their suppliers companies publicly complaining because it's not in their best interest to show a weakness at this time. e.g. if company A says that this will impact them, then company B can use that statement when they pay a visit or market to A's customers.

Fortunately this only impacts the good old USA. The rest of the world can continue to reap the benefits of GPS while they ramp up their systems. (Glonass has been on the rise. Galileo is finally making progress. Compass is on its way and hopefully they will eventually publish their ICD.)

Re:Farm GPS, airplanes, and who owns the bandwidth

[DeadCatX2]

It's not so much that the nearby frequencies need to be silent. I believe it was actually the case that those frequencies were originally licensed for low-power signals. So when the hardware engineer was designing his GPS receiver circuit, he would use the expected max power that could be licensed for that band in his calculation for determining how many -dB/Octave his filter needs. Now LS comes in and wants to relicense that spectrum for signals of many orders of magnitude more power; the circuits were simply not designed to handle this because such signals were illegal at the time of manufacture.

It's not the hardware engineer's fault that the adjacent bands were "zoned" to be residential and now LS wants to come in and build an airport.

Re:Farm GPS, airplanes, and who owns the bandwidth

[sillivalley]

Nope, it's not adjacent channel interference -- the precision positioning people use a correction signal (from a satellite) in L band, below the GPS L1 signal, that is completely swamped by the LightSquared system -- these precision positioning systems, which are also used in highway construction and other large developments as well as in large scale agriculture, are among the systems that the study identified as impossible to make work even with a redesign -- these bands were meant for weak signal reception of satellite signals, NOT for multi-kilowatt ground stations.

And when you talk about adjacent channel, remember that GPS boxes aren't so much receivers as correlators -- and they are working with signals that are effectively below the noise floor -- that's why correlation techniques have to be used. What might be acceptable as adjacent channel in other modes is devastating to correlator-based designs.

See for example the FAA report at:

http://scpnt.stanford.edu/pnt/PNT11/2011_presentation_files/09_Bunce-PNT2011.pdf

Stanford Symposium held 2011/11/17

[sillivalley]

Look at the docs posted for the recent symposium at Stanford:

http://scpnt.stanford.edu/pnt/

Opening comments on how LightSquared destroys GPS:

http://scpnt.stanford.edu/pnt/PNT11/2011_presentation_files/01_Parkinson-PNT2011.pdf

the FAA report on testing:

http://scpnt.stanford.edu/pnt/PNT11/2011_presentation_files/09_Bunce-PNT2011.pdf

The LightSquared idea is a good one, but not on the frequencies they've selected!

Re:Farm GPS, airplanes, and who owns the bandwidth

[Anonymous Coward]

Read more of those issues, or read Inside GNSS: this does indeed impact Galileo and it impacts anything within 600 miles of US borders, which means it impacts intercontinental aviation.

In a letter filed yesterday (July 19, 2011), Heinz Zourek, director-general for enterprise and industry, wrote to FCC Chairman Julius Genachowski that if LightSquared is allowed to begin broadcasting in the band, “What are now neighbour MSS [mobile satellite service space-to-Earth] transmissions at similar receive powers to RNSS [radionavigation satellite service such as GPS and Galileo] would in future be many orders of magnitude higher and with the potential to severely disrupt reception of RNSS signals.”

He cited analysis — including ESA studies —carried out in Europe that showed interference effects to Galileo equipment would occur from 100 meters to almost 1,000 kilometers (620 miles), “depending on the type of receiver being used.”

Emphasis mine. Source: "EC Official Adds Galileo, EGNOS Worries to FCC’s LightSquared-GPS Deliberations,"Inside GNSS, July 20, 2011. That's right, July. The Europeans knew this was going to interfere with GPS/Galileo for aviation back in July. They had tested it, and they had numbers showing how far the interference would spread.

I'll leave it to the tin-foil crowd to speculate on why the FCC is only getting around to publishing its findings now. I'd suggest, though, that what they come up with might not be so paranoid after all in this case. Those who want to dig through some glaring evidence of bipartisan corruption will find it without looking too hard into this story, because the shady deals were conducted practically in the open on this one, from the SkyTerra days on through the past week. The Republicans are already working overtime on trying to assemble a timeline of Falcone's dealings with Obama: if the Democrats were smart, they'd have a team doing the same to show Republican connections, because they are there too (SkyTerra got permission for this back in the Bush era).

The fact that this story is dying in the back pages while Lindsey Lohan's Playboy spread and the circus clowns that have hijacked the Republican nomination get near-orgasmic coverage is a sad comment on how useless journalism has become.