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4G and GPS

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Initially Posted - 04/07/2011 : 13:12:47

Interesting tidbit from the current issue of "Seaworthy", the safety newsletter from Boat/US insurance:

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">The proposed expansion of the 4G broadband Internet service throughout the country, according to the GPS industry, threatens to wreak havoc with GPS receivers. An industry publication called GPS World says 4G transmitters “will create a disastrous interference problem for GPS receivers (complete loss of fix) when in the vicinity [about five miles] of these transmitters.” There are 40,000 transmitters scattered throughout the United States.

A test is being conducted to see which GPS devices are affected and what sort of filtering might work and what it might cost to correct. GPS is now widely used in automobiles, boats, and even smartphones. The good news is that the system is maintained by the Air Force, which isn’t likely to let surfing the Internet interfere with national security.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

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redviking
Master Marine Consultant

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USA
1771 Posts

Response Posted - 04/08/2011 : 06:46:35

The FCC will not let this happen... Too muck stuff runs on GPS now. The whole planet would get lost.

sten

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 04/08/2011 : 08:32:51

I'll wait for the results. GPS will certainly win for the military if there is conflict, but money is more powerful than sense in politics. Recreational users don't have the political $trength of telecoms and buying new equipment could be the suggested solution. It may be much ado about nothing, but it is worth following.

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Voyager
Master Marine Consultant

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USA
5379 Posts

Response Posted - 04/09/2011 : 22:02:15

I read an article in this week's TV Technology magazine, and the company, LightSquared, is very serious. They are a well-connected belt-way player who claims that their adjacent-channel interference will do no harm to GPS signals.
On the other hand, Garmin took two top-of-the-line commercial GPSs (one for ship navigation and another for commercial airplanes) and at 2.5 miles distance from the 4G transmitter, the GPS lost lock. The ship nav unit began to have spurious readings at 12 miles from the 4G transmitter.

Here's a quote from Garmin in the TG Daily: "LightSquared's proposed new 4G network is a disaster for GPS, jamming signals for miles around its transmitters. And it's not just geographically-challenged consumers that will suffer, but 911 systems, air traffic control and the military."

Add to that two important facts:
1. The current GPS satellites have no in-orbit spares. There's a constellation of 24 birds which is the required number for military use. The GW Bush white house cut launches during its two terms, and since 2009, no new birds have been launched. Lose another bird, and the system operates below spec.
2. Sunspot activity until recently, had been at an all time low. Now, sunspot activity is on the increase, and the intensity is expected to grow in the next 2-5 years. The radiation from sunspots tends to degrade and destroy satellites.
These two trends would have been bad enough by themselves, but add to that adjacent channel interference wiping out accuracy from several miles away, and you have a "catastrophe" on your hands.

GPS is not just for lost, clueless drivers who are unable to use a map. They are used in all kinds of applications including law enforcement (ankle braclets for prisoners under house arrest), trucking logistics for just in time deliveries, border-watching survelliance drone aircraft and directions for 911 and first-responders and cell-phone tracking data.

There is a very real possibility that LightSquared will prevail.

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glivs
Admiral

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USA
836 Posts

Response Posted - 04/10/2011 : 06:04:58

Bruce, not arguing that G4 raises serious concerns, but I question some of the details listed.

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">1. The current GPS satellites have no in-orbit spares. There's a constellation of 24 birds which is the required number for military use. The GW Bush white house cut launches during its two terms, and since 2009, no new birds have been launched. Lose another bird, and the system operates below spec.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

The [url="http://tycho.usno.navy.mil/gps.html"]U.S. Naval Observatory[/url] as of this morning lists 31 satellites currently in operation. Twenty-four constitute a full constellation, the others are redundant or held in reserve. The oldest satellite in the current constellation was launched Nov,1990, the newest was launched [url="http://www.usno.navy.mil/USNO/time/gps/current-gps-constellation"]May 2010[/url] and put into service in Aug of that year. This latest is the first of a new suite of satellites of which 11 others are scheduled to be launched. The next generation of "GPS" is supposedly in the works but who knows what it looks like or when it will materialize.

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Voyager
Master Marine Consultant

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USA
5379 Posts

Response Posted - 04/10/2011 : 10:00:24

Gerry.
Thank you for correcting my misunderstanding on that. I apologize for providing out-of-date information.
Good to know that since 2009 (when I learned of the situation), the fleet has been largely restored.

Nonetheless, having a 21 year old satellite that still operates as designed tells me two things:
1. Maybe it should become a spare;
2. The military really do a heck of a job designing and building the birds, as lives depend on them.

Still worried about the interference. Write your senators and congress-persons.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 04/10/2011 : 14:50:22

Probably should wail for the comprehensive testing to finish, it shouldn't take too long.

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