LightSquared Hires Lawyers To Prep For GPS Battle 195
itwbennett writes "Following Tuesday's FCC ruling saying that the company's LTE network interferes with GPS, LightSquared's primary investor Philip Falcone is looking to sue the FCC and the GPS industry. Alternately, Falcone is considering ways to appeal the FCC's decision or even swap spectrum with the Department of Defense."
Re:Oh come on. (Score:5, Informative)
They bought a license to transmit a candle's worth of power on a sattelite based band, and are sad that the FCC won't let them send an arclight's worth of signal out from ground based stations. Ars [arstechnica.com] link.
Re:Oh come on. (Score:5, Informative)
Comment removed (Score:4, Informative)
Tradeoffs (Score:5, Informative)
The GPS on a phone has to operate a few centimeters from a transmitter, and on top of this there is likely all sorts of digital hashing it has to deal with as well, which tends to have wide frequency content (over a short distance). The interior of a smartphone is a relatively harsh RF environment and the GPS needs stronger filtering to operate. This additional filtering (and space constraints that limit component selection) result in more attenuation of the GPS signal, and thus worse fixes. But it doesn't matter because it is just a cellphone, and the GPS is a nice-to-have which can be augmented with other coarse positioning systems when needed.
Navigation systems need to have a stronger GPS signal, so they have more reliable and precise solutions. The designed their filters to adequately attenuate adjacent frequencies, for what they were licensed for, while minimizing attenuation of the GPS band. Furthermore, given the larger size, they can use RF shielding on the cabin as a way to block the closest sources of interference, and only need to design the filters to block signals from the ground. These are higher quality filters (since they can afford the money/space for better components), they are just engineered with different goals. They could have filtered more, but it would have been counter-productive.
LightSquared is proposing to transmit with over 10,000 times the power that they are currently licensed for, which is more than 1 million times the power of GPS signals here on the ground. Even if you were to upgrade every GPS system out there with the best filters we can make today, you would still have either increased interference from the proposed LightSquared system, or attenuation of the GPS signals. And LightSquared has yet to offer to upgrade every GPS system out there.
The fact is that LightSquared picked the worst possible piece of spectrum to convert to terrestrial broadband. They acquired the company who owned it for cheap because everyone else (all the incumbent wireless operators) realized this, and spend their money licensing other (more expensive) spectrum instead. LightSquared has no one to blame here but themselves.
Re:Oh come on. (Score:4, Informative)
Um, no. The FCC only licenses transmitters, not receivers. The only transmitters in GPS are in the satellites. And part B is not a license, it is a section of type 15 UNLICENSED transmitters (specifically unlicensed devices which are unintentional transmitters, like computers).
Re:Oh come on. (Score:5, Informative)
As I understand it
Lightsquared were/are a sattelite communications provider and owned a peice of spectrum intended for sattelite downlink (where signal power at earths surface would be very low) close (spectrally) to GPS. According to wikipedia they got permission to make ancillary use of this spectrum terrestrially and are now trying to get permission to use it for pure terrestrial cellular devices. However terrestrial transmitters mean much stronger signals at the earths surface. Signals that are close in spectrum and widely different in power are problematic due to imperfect filters and nonlinearities in both tranmitters and receivers.
If they succeed they will make a mint, if they fail then it will likely be a massive hit to thier buisness. Especially if in the process of failing they were to lose the ability to run any terrestrial services in the band.
It's kind of like buying land/buildings with the intent ot trying to get "planning permission"* to build something and/or to change the use of the property. If you get the permission you can make a shitload of money but if the council decides your planned use is inappropriate for the area you can be stuck with property you can't do much with.
* This is a UK term, I dunno what the american equivilent is
Re:So let me get this straight... (Score:4, Informative)
The FCC only certifies TRANSMITTERS (both intentional and unintentional transmitters). GPS receivers are not transmitters.
The "must not interfere" and "must accept all interference" rules which people on here are so fond of quoting have nothing to do with technical requirements. If they were technical requirements the consumer would have no reason to know about them. They are USAGE requirements. "Must not interfere" means that, even if your type accepted device is operating 100% properly, if it is causing interference with licensed operations you must stop using it. "Must accept all interference" means that if something (licensed or unlicensed) is interfering with your transmissions, that is just too bad.
Re:So let me get this straight... (Score:4, Informative)
> not susceptible to interference from lawful emissions in other parts of the spectrum.
_Lawful emissions_. GPS uses spectrum within a portion of the L-Band allocated for use in space -> ground communications. This means that future allocations on adjacent bands should be very low power. Indeed, I'd say that's rather the entire point of having a blocked out bit of spectrum for satellite communications: They must be a much lower power, so receivers can't easily filter out much more powerful ground based interference. By blocking ground signals a good distance from satellite ones you make filtration much easier.
GPS receivers were built with the expectation (if not guarantee) that interfering signals would be roughly at the same power as GPS. However, the transmitters Lightsquared was planning to build would be, literally, one million times stronger than GPS on a good day (-70dBm vs -130dBm). So, I'd hardly call such interference 'lawful' just because the FCC thought they could change the law after the devices were built.