No. 1 Story on Fox News this morning - LightSquared

Is this possible?

"A source familiar with the technology told Fox News that the LightSquared spectrum would be 5 billion times stronger than the military's GPS system, rendering the military's system almost useless."

Keith

Well, decibels are a logarithmic scale.

http://en.wikipedia.org/wiki/Decibel

Someone here must know the output levels of GPS transmitters and the proposed output levels of the LightSquared towers.

> Is this possible?
>
> "A source familiar with the technology told Fox News that the LightSquared spectrum would be 5 billion times stronger than the military's GPS system, rendering the military's system almost useless."
>
> Keith

Possible? Yes. In fact, more than possible, it has already been proven.

The signal strength coming from the GPS satellites is equivalent to a 3 watt light bulb, plus that signal source is 21,000 miles away from your receiver. As you can imagine this means the signals our units gather are very very faint.

Now imagine a radio tower 2 or 3 miles from your receiver broadcasting at 10,000 watts. You get the idea.

I saw the graphics at the ACSM conference. The anti-Lightsquared people were being kind when they decided to compare the signal strength a mile away from the tower. Get closer and the signal strength disparity is much worse.

I also found it interesting that the Lightsquared rep was saying that their plans would mean that 95% of all users would be unaffected by the towers. Of course, they are counting a college kid with a cell phone (they are all GPS enabled these days) as exactly the same as a Survey Company's very expensive receivers.

Larry P

i heard a similar number. keep in mind, keith, that the gps signal is coming in from, what, 21000 miles out? has to penetrate ionosphere, troposphere all from a solar powered transmitter. the signal strength gets degraded.

now from a monopole that is maybe a couple miles away, and fed from ac power. seems a likely factor to me, but i am not a scientist.

edit: wow, larry, we're thinking on the same channel

FYI...here's a News Release from June 2011 from the “Coalition to Save Our GPS”...
FOR IMMEDIATE RELEASE: June 9, 2011
CONTACT: Prism Public Affairs
Dale Leibach: 202-207-3630 or [email protected]
Anne Tyrrell: 202-207-3632 or [email protected]

FCC Should Focus Its Efforts on Finding a Practical Way for LightSquared to Proceed
Tests Confirm Planned Network Will Cause Substantial Interference

WASHINGTON, D.C., June 9, 2011 – Speaking today at an event sponsored by the National Space-Based PNT Advisory Board, Trimble Vice President and General Counsel and founding member of the “Coalition to Save Our GPS” sent a strong message to the Federal Communications Commission (FCC):

“The test data discussed today makes clear that there is substantial interference to GPS if LightSquared turns on high-powered terrestrial facilities in the spectrum next door to GPS,” Kirkland said. “The data confirm what the industry told the FCC before it granted the waiver, and also confirms that there is no viable technical fix. It’s time for the FCC to stop squandering resources trying to find a solution to an unfixable problem. Instead, it should focus its efforts on finding spectrum that LightSquared can operate in –where LightSquared won’t interfere with GPS.

“When it comes to broadband and GPS, it’s not an either/or situation – the United States can, and should have both. LightSquared says it has other spectrum and it should use it,” Kirkland said.

At issue is an unusual waiver granted to LightSquared in January by the FCC’s International Bureau allowing the dramatic expansion of terrestrial use of the mobile satellite spectrum (MSS) immediately neighboring that of the GPS - utilizing extremely high-powered ground-based transmissions that tests have shown will cause interference to hundreds of millions of GPS receivers across the United States.

At the event, Kirkland and government representatives discussed testing conducted to measure interference to GPS receivers used in aviation and other critical government applications. In at least one test, LightSquared failed to deliver test equipment that matches its proposed operations, thus causing optimistic results – and even those optimistic results showed interference.

“It’s clearly a good thing that LightSquared is trying to do,” Kirkland said. “No one in the GPS industry opposes its goals of increasing wireless data capacity and competition, but the available data has shown overwhelming interference, and LightSquared should not be allowed to launch in the spectrum adjacent to GPS.”

A joint industry report is due to the FCC on June 15th, when the FCC will begin a public comment period before making its final decision.

About the Coalition
The “Coalition to Save Our GPS” is working to resolve a serious threat to the Global Positioning System. The FCC granted a highly unusual conditional waiver for a proposal to build 40,000 ground stations that could cause widespread interference with GPS signals – endangering a national utility which millions of Americans rely on every day. The conditional waiver was granted to a company called LightSquared.
www.SaveOurGPS.org

I thought most "GPS" cell phones used nearby cell towers for triangulation, and not the signals from GPS satellites...

The original release from the Daily Beast:

The Daily Beast: White House Pressure for a Donor?

GPS World:

GPS World: White House May Have Pressured General to Change LightSquared Testimony, Reports Daily Beast

Peter Lazio