Who is our resident GPS expert?

[Hawkmoon]

http://www.washingtontimes.com/news/2011/sep/14/virginia-company-nears-breakthrough-in-nationwide-/

Interesting little squabble. New company wants to use the portion of the electromagnetic band ADJACENT to the portion used by/for GPS to revolutionize cellular services. GPS industry claims the new system will cause interference, the new company says the GPS folks shouldn't have built a system that's susceptible to interference from outside of its assigned portion of the spectrum.

Who to believe?

It's tough to argue with the new company's logic. The GPS argument is akin to television channel 7 objecting to anyone transmitting on channel 6 or 8 because of interference. Isn't that why they assign frequencies and spectrums? Aren't companies and systems supposed to operate wthin their assigned frequencies and bands?

[Scout26]

From what I understand the GPS portion is supposed to be "a quiet neighborhood", meaning very low power in nearby bandwidth's.

This company gambled that it could use the nearby frequencies and develop the tech that would still be somewhat quiet. (not interfere with GPS)

However it appears that they can't make it work "quietly", so they want to turn it up to 11, and a now acting all butthurt when the .mil and GPS folks are telling them "Nope, turn it down."  But it won't work then (meaning they lose their money)

So they get the WH to try to "lean" on the 4 Star to change his testimony.  Smart man that he is he tells Congress. 

Now, the WH is all butthurt that someone told them "NO', you can't just wish for rainbows and unicorn farts.  It don't work that way.

[TechMan]

Another article from a wireless publication.
http://www.dailywireless.org/2011/09/09/lightsquared-another-plan/

[grislyatoms]

Hi neighbor! Just bought the house next to yours, the real estate wasn't quite enough but I think we can make it work!
Hi neighbor! Would you mind if we put our mailbox a little on your lawn? Just because it interferes with the driveway!
Hi neighbor! Need a bigger mailbox now to handle all this mail!
Hi neighbor! We sank millions into this project and now we need your garage, and if we don't get it, we're going to court!

Not sure exactly where GPS bandwidth falls anymore, but the FCC allots ranges just like this. Any dev. company worth it's salt is going to avoid encroaching on an existing service. There are some exceptions, and the FCC has granted them, but with GPS? Ain't going to happen.

Oh, and I'm not a GPS expert by any stretch. I do have FCC RT Operator, GMDSS, and radar endorsements though.

[charby]

http://www.washingtontimes.com/news/2011/sep/14/virginia-company-nears-breakthrough-in-nationwide-/

Interesting little squabble. New company wants to use the portion of the electromagnetic band ADJACENT to the portion used by/for GPS to revolutionize cellular services. GPS industry claims the new system will cause interference, the new company says the GPS folks shouldn't have built a system that's susceptible to interference from outside of its assigned portion of the spectrum.

Who to believe?

It's tough to argue with the new company's logic. The GPS argument is akin to television channel 7 objecting to anyone transmitting on channel 6 or 8 because of interference. Isn't that why they assign frequencies and spectrums? Aren't companies and systems supposed to operate wthin their assigned frequencies and bands?

I had read somewhere about that, I think it was more related to WAAS and may hurt some of the consumer line GPS units accuracy.

[AJ Dual]

From reading the second article, they're hashing it out. And the company is even going to throw some development into making GPS even more sensitive to it's own frequency and ignoring interference from nearby bands.

The main problem is that we're running out of space in the RF spectrum as ever more devices and data services come online. Eventually AM/FM will shove around and go digital, which will free up a fair amount, like the retirement of VHF in favor of all-UHF digital TV transmission.

But all in all, the spectrum is already pretty crowded, and we've got ever more demand for it.

[birdman]

I had read somewhere about that, I think it was more related to WAAS and may hurt some of the consumer line GPS units accuracy.

In other words, the vast majority of users.

Having done a lot of work on some sensitive GPS stuff...this is a bad idea.  Light squared should be told to pound sand.  "making gps more sensitive" translates to "everyone else has to re-capitalize their existing stuff because we can't make ours work".  It's garbage.  There are many others that have tried in the past to do tuff close to the GPS bands, and were told they couldn't for all the same reasons...and they went and found other spectrum, for higher cost, and some made it work...rather than getting the WH to push it for politics. 
The GPS bands were chosen for a very good reason, back when the spectrum was cheap and they could have picked anything...the reason light squared was able to claim the costs they do, was they convinced others that they could make it work...and thus got previously denied spectrum cheap...and now they can't.

Yeah, it primarily would affect WAAS, HOWEVER, it would also affect any low SNR uses...or those that can't work without WAAS...or those that RELY on high SNR and WAAS (aircraft, so kiss GPS aided auto land and free flight goodbye under less than perfect conditions). 

So, true, under perfect conditions, it would likely have little input...but in imperfect conditions (weather, ionospheric scintillation, etc) it could compromise things...that's why current GPS has major margins.  The govt gave them an inch initially (as modern receivers don't need the huge original margins due to improved electronics) and now they want a mile. 

I say the general was dead on.   Additionally, if one looks at lightsquareds economics, it is very doubtful they will ever get the subscribers they need to be profitable, and considering they are already getting/in the process of government money (rural broadband initiative)...they will either need continuous infusions, or die on the vine...but then their spectrum and hardware could be resold, and the negative gps impact will last forever.

[Hawkmoon]

Another follow-up: http://www.thedailybeast.com/articles/2011/09/15/lightsquared-did-white-house-pressure-general-shelton-to-help-donor.html

[MicroBalrog]

But wait.

LTE services are already deployed in countries other than the US (Russia most prominently). How does GPS navigation work for clients in those nations? Does Yota's LTE mess up GPS receivers in Moscow?

[birdman]

But wait.

LTE services are already deployed in countries other than the US (Russia most prominently). How does GPS navigation work for clients in those nations? Does Yota's LTE mess up GPS receivers in Moscow?

I dont believe the other 4G-LTE services use spectral bands that close to GPS.  For instance, by definition, Verizon's LTE bands have to be further from GPS (since they can't be closer, and they by definition can't be the same as lightsquared's), thus, less interference.

The basic problem is since GPS receivers have to pick up very faint signals, they tend to use active antennas with front end amplification, and since all filters "roll off" outside of their pass bands, even a small amount of nearby transmissions in adjacent spectra can overwhelm the ability of the receiver to detect the faint GPS signal.   This is further exacerbated by the fact that the modulation method used for 4g-LTE results in high peak-to-average powers, and thus even though the average power of the transmission may be low, the periodic random peaks are significantly higher, and can easily louse up the ability of the GPS receiver to properly time the transmitted code.

[KD5NRH]

It's tough to argue with the new company's logic. The GPS argument is akin to television channel 7 objecting to anyone transmitting on channel 6 or 8 because of interference.

It's more like complaining because your neighbor built a 3x3 foot backstop right next to your bedroom window; after all, he'll only be shooting at an 8.5x11" target in the middle of that backstop.

[birdman]

It's more like complaining because your neighbor built a 3x3 foot backstop right next to your bedroom window; after all, he'll only be shooting at an 8.5x11" target in the middle of that backstop.

In this case, the above analogy would be more accurate if he was shooting a shotgun with 00 from 40yards...then told you that your windows would need to be "a little bit thicker" because the pellets are slowed down at that point.

I've read some follow up reporting...if it is as bad as some of the tests and simulation says....good luck.

[RaspberrySurprise]

So basically the area around GPS is zoned as residential but lightsquared wants to put the equivalent of a jet engine testing facility in next door?

[TechMan]

So basically the area around GPS is zoned as residential but lightsquared wants to put the equivalent of a jet engine testing facility in next door?

Ayep

[AmbulanceDriver]

And then tell people they need to wear earplugs.

[birdman]

And then tell people they need to wear earplugs.

Worse, it's not a correctable nuisance that is the impact.  If we are using the jet testing analogy, it would be like having an area where quiet was required for it's use....
So let's say we have a hypothetical building housing Allcorp Inc (a division of skynet ltd.) and they specialize in neurosurgery, LASIK, semiconductor manufacturing, large telescope astronomy, seismic measurement, and have designated quiet areas as well, for the final hole of the PGA championship, panda bear mating, refuge for crippling insomnia, blind people, and a bat cave.

They have built this building in a location where previous laws have restricted any normal loud noises to outside of a mile away.  Since then a company that specials in seismic profiling (thumper trucks), open pit mining, rocket engine testing, and explosives development moved in a mile away, and was allowed to do so because they said they would limit their own noise with an anechoic room the size of the super dome...however, after they got the permits, they now say the dome costs to much, and their noises aren't that different than "normal" noise...so they want to not build the dome and say if the noise bothers you, you hav to build your own dome.

That's really what is going on.

And a more fun note..,all the studies I've seen are base-station related...not handset related (which use the same bands, albeit at far lower power)...however, those could be much closer to the gps devices.  I would be willing to bet that an operating customer transceiver would have similar (albeit much closer range effects).  Given normal base station to handset power ratios, if a base station would cause severe problems out to 15km, a handset would do the same out to 500m or so.  (and a group of handsets, let's say 100, would affect an area 5+km in radius).  Again, this could be bad.

Other companies have encountered this before, and had to change THEIR operations...iridium for instance turns off their links over arecibo, the VLA, and other radio telescopes (as their frequencies cn interfere with the bands used for radio astronomy) to avoid interference.

Lightsquared is being stupid.   Unless I'm missing something, this is bad.

[Hawkmoon]

Thank you for the enlightenment (no pun intended).

Now that we have a technical explanation, I suppose the next question is: How deep into the White House pockets is Lightsquared? Is this another "stimulus" sweetheart backed by the Big O, like that solar company that just went belly-up?

[TechMan]

Thank you for the enlightenment (no pun intended).

Now that we have a technical explanation, I suppose the next question is: How deep into the White House pockets is Lightsquared? Is this another "stimulus" sweetheart backed by the Big O, like that solar company that just went belly-up?

Here's your answer.

Philip Falcone is one of the big backers of LightSquared, a telecommunications company that wants to develop a nationwide satellite phone network. Falcone is a billionaire hedge-fund manager who is known as “the Midas of misery” for his skills at exploiting economic failure. He is also a big political campaign contributor, usually to Democrats.

Read more: http://www.foxnews.com/politics/2011/09/16/scandals-undercut-obama-re-election-message/#ixzz1YFZOiWGm

[birdman]

It's tough to argue with the new company's logic. The GPS argument is akin to television channel 7 objecting to anyone transmitting on channel 6 or 8 because of interference. Isn't that why they assign frequencies and spectrums? Aren't companies and systems supposed to operate wthin their assigned frequencies and bands?

Just noticed this and thought of something else.  Whenever spectrum is allocated, users have to minimize spill-over, and in some cases, purchase broad enough spectrum so their needed bandwidth has sufficient guard bands to avoid interference (as if you do interfere, you can be sued).  For very sensitive applications, guard bands are imposed (gps).  In your tv channel analogy (while not entirely accurate, as TV's use AMD require completely different RF front end designs that are far less susceptible to adjacent band interference), each TV channel transmits on a bandwidth that is smaller than it's actual reserved bandwidth, hence the guard bands.  In this case, the govt gave them the benefit of the doubt and reduced the gps guard bands, GIVEN they PROVE they don't cause interference...(which they were originally confident in based on their transmit freq's and power), now after further analysis, they found that to make it work it does, which means their initial deal (you get the bandwidth IF you don't interfere) should be void...but now they are whining to their investors, who (like smart investors) donated to the pols so when stuff like this happens, they "know a guy". 

I wonder why Obama hates GPS so much...it's a perfect example of the government providing a service to the people.  Maybe because while it did cost a bunch, I bet if you put a one-time surcharge of <$1 on any GPS receiver chip, you could easily pay for the entire constellation and it's maintenance.  So maybe it's not the best example, as it could be easily privatized and profitable.

[MicroBalrog]

How can it? I mean, GPS chips are receivers-only.

We could hardly stop a manufacturer in China or Somalia from making a chip that also receives our signal.

[birdman]

How can it? I mean, GPS chips are receivers-only.

We could hardly stop a manufacturer in China or Somalia from making a chip that also receives our signal.

How can it what? 

[CNYCacher]

I think he means "How could you charge a $1 surcharge on any chip?"

[dogmush]

I think he means "How could you charge a $1 surcharge on any chip?"

The easy way would be to reintroduce the error in the signal and then license the software needed to get a usable position.

[birdman]

The easy way would be to reintroduce the error in the signal and then license the software needed to get a usable position.

Even easier than that.  The GPS system was designed to have multiple codes, each with different levels of potential encryption and error levels.  By simply licensing encrypted firmware to production companies, only those who paid would be able to obtain their needed precision.  A company would purchase X licenses, or a fixed fee production license, subject to revocability if they violate the agreement.  Periodic code changes could be used to ensure compliance.  In effect, a civilian version of the M code.

True, it would only be as "secure" as normal software DRM, but unlike normal software, each product, by definition, has a known hardware spec it must work with, so that simplifies things.

In any case, it wouldn't take much, $0.25-0.50 per year effective cost per user (effective meaning actual cost degraded by piracy, etc) to fully fund the system given the large (billion-plus) users. 

I don't know about you, but I would pay a buck a year to have assured GPS, and actually quite a bit more.  The incremental cost could be built into the devices, and would be negligible ($1-2 increase on a phone or satnav) and the revenue could be used to enhance the service (more, higher power satellites, tiered service, etc), while freeing the DOD funds to be usedon more pressing needs.

Anyway, just thinking out loud.

[CNYCacher]

The easy way would be to reintroduce the error in the signal and then license the software needed to get a usable position.

Yeah, turning SA back on was my first thought as well.  You're gonna nerf every consumer-model GPS made since the Clinton days, though.

I'm not comfortable with the entire concept, though.  Charging for GPS is just another pretty box to .gov's Pandora