Planned wireless Internet network threatens GPS

This could be a game changer in the USA
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Joelle Tessler, AP Technology Writer, On Wednesday April 6, 2011, 3:02 pm EDT

WASHINGTON (AP) -- A new, ultra-fast wireless Internet network is threatening to overpower GPS signals across the U.S. and interfere with everything from airplanes to police cars to consumer navigation devices.

Whole page article at this link
Planned wireless Internet network threatens GPS - Yahoo! Finance

Aiken -

Thanks for that. It is an interesting article...

D.

Prior to the LS issue, the adjacent spectrum was not a problem. The FCC had set aside ALL of the surrounding spectrum for - and this is KEY - "space to earth" communications (see http://www.fcc.gov/o...le/fcctable.pdf ). As received on the planet here, those wind up being very low power signals. With very low power signals being received from space, there was no need for concern by the GPS manufacturers.

LS started talking space to earth comms, and then in a bit of a "bait and switch" move, tried to slide through a deviation for spectrum use for their terrestrially based system -- using that spectrum previously set aside for ONLY space to earth comms. Unlike satellite signals, which due to distance and spread tend to be rather weak, these ground based systems would likely swamp an existing GPS unit's ability to reject the interference from adjacent frequencies.

So while it's true that the selectivity of commercial and consumer GPS receivers wasn't exceptionally tight, neither was there any reason for it to be. During the design phase, there was NO anticipation of a terrestrially based use of the adjacent spectrum. There wasn't SUPPOSED to be terrestrially based equipment there, but LS's attempt (and so far, it's only that, thanks to some alert people out there) to make ground based use of "space to earth" spectrum was a game changer.

LS tried to slide one by the FCC, and the FCC nearly let them. You can determine for yourself whether money and politics had a hand in this, but even assuming the unlikely idea that it did not, it was clear that the FCC did NOT do its job when reviewing LS's application for a deviation from allowed use of spectrum.

All we can do now is hope that sanity is brought to this issue and soon. Phil Falcone / LightSquared / Harbinger have a huge ($billions) financial stake in this slight of hand if they can pull it off. Then again, if the civil and criminal investigations of Falcone by the SEC for prior bad acts pan out, perhaps all of this will be moot. This LightSquared scheme is already considered by many to be seriously underfunded, and Phil's empire isn't nearly as cash rich as it used to be. That said, he's put more than half of his eggs in this LightSquared basket in hopes of recouping his prior losses, so you can bet he'll fight tooth and nail.

Nobody designs ANY receiver with vastly (and vastly is the right word in this situation) more sensitivity or selectivity than the application warrants. Neither are free. There's even a point where it's not even possible. There's no point in building in unnecessary cost in electronic gear.

Let's draw a fair comparison here. You can pick up a simple AM radio that will do just fine for picking up the AM broadcast band. Nothing below the AM broadcast band, and nothing within it, is permitted more than 50KW power in the U.S. (We'll leave aside such Mexican border anomalies as XERF for now). The design of a typical radio can handle adjacent channel interference pretty well. However, even those suffer when trying to listen to a distant station on one frequency (e.g, 540KHz) when there's a boomer 50KW location station on an adjacent channel (550KHz - and we'll leave aside that this particular frequency doesn't allow for 50KW night use - it's JUST an example). Some manufacturers put some extra cash into the selectivity of the unit, and do a better job of rejecting such adjacent channels. Some don't handle it very well at all. But the cost of selectivity, while not free, is at least within reason relative to not doing it. Makes for competition in the market. A professional unit will have better selectivity than your dime store five transistor special.

Now for the ugly comparison. The FCC is suddenly going to let me deploy MEGAWATT transmitters all over the country at 530KHz, focused on urban markets. Yes, megawatt. That's a more than fair ratiometric comparison to 50KW of what's about to happen vs. space signal strength. Good luck with that. Try finding an AM radio that will successfully pull in that signal on 540KHz now. You can't afford one, and so far, nobody makes one. THAT is the moral equivalent of what the FCC did when allowing the adjacent channel terrestrial equipment. It'd be just like allowing megawatt stations to pop up on 530KHz. NO manufacturer would EVER put the kind of money into a consumer rig necessary to reject a signal like that on the odd chance that the FCC would have their collective heads up their collective patoots and allow something like that to happen. And if it did happen, you don't retrofit the receiver to solve the problem. You start over with the hardware design. That's what would be necessary for even the higher end GPS gear to operate with a powerful land-based signal sitting right under L1. Don't expect to see the FAA certified receivers getting upgrades to solve this either. I guess you can keep the case and the display. It's a whole new RF front-end and I.F. section at a minimum. Depending upon how it all pans out, it might not even be practical to build something that would cope with the LS transmitters. We'll have to wait to see what comes of the testing. I understand they have until June to duke it out in the labs, assuming Garmin and the rest of the working group can procure something that mimics the LS equipment. From what I'd heard, LS wasn't in any hurry to help with that.

At some point, the finest hardware made can't sort it out. Initial testing with a consumer grade Nuvi and a Garmin aviation unit says this is precisely what happens, and the distances they projected for interference, and finally loss of lock, were not good. The Nuvi was projected to become useless at about 2/3 mile from the transmitter, and the GNS 430W aviation unit at an astounding 5-1/2 miles out. Without seeing the test plan, it's impossible to know whether these initial findings will continue to hold in final testing, but if they are even remotely indicative of what the LS equipment causes, it's a non-starter.

Given the significant hit to the Garmin aviation unit, and the dramatically increased dependence upon GPS by the aviation industry and FAA, I believe that we have no real reason to fear the end result of all of this. Someone will either sort out the problem to (at a minimum) the satisfaction of the FAA, or the FCC will have to put its collective tail between its legs and retract its conditional authorization for the LS request for 'deviant' use of the spectrum. Or the entire enterprise may fail on its own. The plan may fail due to 1) underfunding, even with half of Falcon's money already in the pot (40,000 sites is a bunch of equipment to buy, negotiate site costs for, and maintain) or 2) Falcone might not be in a position to see the deal through due to his SEC issues, or 3) members of the US Congress may prevail upon the FCC to review their very "unique" handling of the LS petition - which could still be denied out of hand if the politics eventually go the wrong way.

I would imagine the FAA and US military might have more impact in this decision than the GPS manufacturers, I was surprised when I first saw this issue a few months ago that LS has been allowed to get as far as this with the proposal - Mike

While this would be an inconvenience for the military, it wouldn't be a game changer. They're running much of their GPS system down in the L2 band, far away from the frequencies involved. The FAA, on the other hand, seems to be the key. Still, the FCC has said that they won't make a final decision on the LS application until it can be demonstrated that it won't degrade consumer equipment in L1, either. We'll see.

I just googled " Phil Falcone Obama "

Like Artie Johnson used to say, "verrrry interesting"

There may be political stink all over this. I guess we will just have to wait and see just what are the priorities of the federal government and the FCC.

This should raise a few eyebrows.... political agenda anyone?

LightSquared: Did White House Pressure General Shelton to Help Donor? - The Daily Beast

Seems congress is finally going to require more testing maybe.


And some more skulduggery
Emails show wireless firm's communications with White House as campaign donations were made | iWatch News

"Any suggestion that we have run roughshod over the regulatory process is contradicted by reality".

The "real" reality is that they tried to slide a request for a deviation from accepted spectrum use through the FCC. It was very nearly rubber stamped in spite of the obvious technical problems. The "alternate" realities of which LightSquared's Ahuja speaks are the financially painful results of being caught at it. Cry me a freaking river.

"For a company that allegedly is ‘wired’ inside the Beltway, we've been unable to even get the House Armed Services Committee to allow us to have one representative at today’s hearing — a hearing in which we are the subject,” he said."

Having already co-opted the White House, and by extension, the FCC, they assumed their scheme would be approved, and never thought they'd need support from the HASC, much less the DoJ... else I'm sure they'd have done more work there, too.

Back in the day, a friend of mine did an analysis of how many people you need to bribe to buy anything in the USA.

Initially, the analysis pointed to president, 50%+1 of the House, and 60 Senators.

It was a sad state when considering how easy it is to buy a dictatorship, but luckily I reminded him of the constitutional congress which could override the dictatorship...

OK, back on topic now...