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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."
One of the big issues is that those giant combines and harvesters on farms use GPS, so the farming industry is upset http://westernfarmpress.com/government/lightsquared-threat-gps-even-filters Lightspeed owns the bandwidth adjacent to GPS, but the GPS devices are still affected by transmission on lightspeed's bandwidth. So it isn't really "lightspeed zmog destroy teh GPS" by doing some dastardly deeds, it is them trying to use the bandwidth they purchased and older GPS devices not able to handle the interference (even tho they are class B and must not create interference and must accept interference). Airplanes are another issue with interference. http://macsblog.com/2011/02/should-i-worry-about-gps-jamming/ really, though, just a clash of the lobbyists in washington on who has to pay extra to make lightspeed able to use their bandwidth
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.
Then you'll need to get your information somewhere besides hotair.com.
When a reputable news source reports this, it will mean a lot more.
TFA is from Business Week. The HotAir.com article only quotes from Business Week and includes other relevant facts that seem well sourced.
I'm not sure how the GP ended up talking about Republicans, but this was reported by a reputable news source.
[Fuck Beta]
o0t!
Let's get over the sensationalism and realize the real problem: We had false expectations of GPS and therefore should not have depended on this technology in defense systems.
You do realize that the US military owns the GPS system. It seems to have worked out pretty well for them. Of course, no tech is perfect but I don't understand what you're whining about. It's not like Lightspeed is going to put transmitters in Afghanistan and if some nefarious persons try to block GPS signals with a transmitter well, the military has some nice little tools to solve that problem.
Faster! Faster! Faster would be better!
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!
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
And Philip Falcone is a huge donor for the Democratic Party.
According to Wikipedia
Not what I'd call a "huge donor for the Democratic Party".
Well, what he said was that the moderators can't handle the truth. Then, in the next sentence he mentioned corruption which I inferred to mean that whether the corruption is in the DNC or the RNC, it shouldn't matter to the moderators.
Yeah but that was 2010.
It's true that the Democratic party received about $20k from Falcone in 2010. But the Republican Party received nearly $50k in 2008.
If you go through his political contributions he tended to shotgun across party lines. And none of the money in 08 was for Obama. It was almost exclusively for Senatorial candidates and Giuliani and Chris Dodd.
http://www.campaignmoney.com/political/contributions/philip-falcone.asp?cycle=08
I have no political ties to LightSquared but considering they're trying to blanket the nation in broadband... I'm really hoping they resolve these interference issues as well. Not because I voted for Obama but because I want to see technology succeed. I also want to see white-space succeed which is another initiative the Obama white-house has advocated for. Again, not because of my voting registration but because I agree with their stated agenda of increasing access to highspeed internet.
GPS is *designed* to listen to frequencies outside it's transmission frequency. Ya know why? These satellites are zooming around the earth, causing the received signal on the ground to be different. It's called the Doppler Effect. It's somewhat of an important rule in physics.
LightSquared's spectrum is only licensed for satellite transmission, which is why they were able to buy it so cheaply. And if they used it as such, there would be absolutely no problem! Now they want to use it on the ground at much higher power, which will cripple ALL GPS devices. It's like trying to hear someone whispering in one ear while someone else is yelling in the other.
It has nothing to do with shoddy GPS engineering and everything to do with LS trying to use their spectrum completely inappropriately, then lying and saying they can fix it when the only fix is to change the laws of physics.
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.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
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.
A notch filter on your IF stage (after the pre-amp) doesn't affect receive sensitivity. The front end filter is just there to block IF and outband frequencies that would add/subtract to get IF.
Your comment is typical of paid pro-GOP astro-turfng on Slashdot.
Falcone is a registered REPUBLICAN and there is no record of any donations to the Obama campaign. Apparently he did make some donations in some congressional races, but the bulk of his donations were to REPUBLICANS.
Simply put, LightSquared should have known that use of high power terrestial base stations could adversely affect GPS receivers and they should have made an effort to see if a work-around was possible before acquiring rights to the frequency bands. Since they didn't, LightSquared management have probably opened themselves up to shareholder lawsuits.
The original allocation for the LightSquared frequencies was for satellite based transmitters and it is up to LightSquared to prove that shifting to terrestial transmitters will not cause harmful interference.
A Shadeless room is a brighter room.
So if LightSquared goes live, 75% of consumer (and possibly commercial) GPS units will have serious problems.
If you had been following along, you would know that consumer GPS units are not affected. That has already been resolved when LightSquared agreed to hold off using the upper band for a period of time, allowing most consumer GPS units to be replaced by normal obsolescence. Their use of the lower band will only affect precision GPS units.
If I was in to conspiracy theories, I'd say that little fact is left out of news articles intentionally to rile up the general population against LightSquared.
Looking at it as someone who has been following this for months, and has no stake in the game either way, it looks more like this; precision GPS manufacturers didn't feel the need to filter a band in between two that they were using since it wasn't really being by anything with any power, and it could have cost them a few more pennies per unit. And then LightSquared managed to somehow get the FCC to consider opening the band to terrestrial transmitters. Now it's a multi-billion dollar pissing match. Nobody is completely right, and nobody is completely wrong.
Another day, another update to a Google android app.