GPS freqs at risk by LightSquared Inc

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Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Apperantly in our rush to ipod, andorid and G5 technology we forgot that there is a limit to how closely you can stack the frequencies together and still get everything to work.
LightSquared is setting up a ground based high power next gen link for all you folks that are using your PDAs while doing what ever it is you do all day. Unfortunatly the band (L-band) they are going to use at 1000 watt level is right next to the band that GPS uses (at micro watt levels). Bleed over is expected which means NO GPS. LightSquared is doing this nationally (US) so all you non-US folks have nothing to fear.
Call the FCC and your congressman, LightSquared is using the time tested method of calling GPS something else to hide the criticality of what they are doing. In this case GPS becomes RNSS (radio navigation satellite service)

http://en.wikipedia.org/wiki/LightSquared
 
Roger Long

Roger Long

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Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
After the way industry and governement have handled Internet security, our financial system, and just about everything else, I can very easily believe that this could be allowed to happen.

More:

http://www.gpsworld.com/gnss-system...us-gps-jamming-fcc-approved-broadcaster-11029

The f**kers are working with the GPS industry to see which models will have to have filtering added. Of course, the GPS industry loves that because many existing units will suddenly become obsolete and they have to sell millions of new ones, crying all the way to the bank.

http://www.insidegnss.com/node/2471

Google "Lightsquared GPS interferrence"

 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
So what you are saying is an enterprising young man with a resonant antenna could make a lot of money selling them to those poor saps that find themselves obsolete. This one is pretty easy to fix as long as LightSquared keeps their “out of band” transmissions in order.
 
Roger Long

Roger Long

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Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Bill Roosa said:
So what you are saying is an enterprising young man with a resonant antenna could make a lot of money selling them to those poor saps that find themselves obsolete.
Click to expand
I don't know much about radio so I'll take your word for that being a solution. I hope you are right. However, I'm sure Garmin won't be selling us those antennas, they'll tell us we need a whole new chart plotter (with the magnetic door latch and auto routing that takes you over rocks) :) My Garmin antenna sends NEMA to the chartplotter and not raw GPS signal so Garmin can chose to put the filtering in new chartplotters and make zillions more money forcing complete upgrades.

We have it relatively easy in boating because we can just plug in the new antenna. Pity the poor pilots, even more exposed to this interference, with their 10K and up GPS units. Due to FAA regulations and inertia, any aftermarket resonant antenna would take about a decade and a million bucks to receive FAA approvals.

Would it be feasible to install some kind of plug in filter box between a GPS antenna and the GPS? What about the laptop puck dongles?
 
KD3PC

KD3PC

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Sep 25, 2008
1,069
boatless rainbow Callao, VA
" This one is pretty easy to fix as long as LightSquared keeps their “out of band” transmissions in order."

like that is going to happen..??? Not likely. Google BPL, they promised the same thing...and then found out, it could not be done. Brute force can't be put back or contained once emanated.

Industry spent millions to try to do BPL (broad band over the powerlines) in a similar stunt, baffle the FCC, municipalities (see Manasas, VA) and collect "development grants" to do so. Several years later, it still doesn't work and they never did keep things in band. The lawsuits are still being swung to FORCE people to accept substandard engineering and antenna practices by the proponents, for their financial gains. Damn the science or the facts.

Similarly the Congress, with no radio experience, is currently fixing to take away the 440Mhz ham bands to be auctioned off...this after a great showing that in an emergency (9/11 and Katrina) ONLY the hams have ANY communication capabilities that can be deployed or used. The wonderful cell phones and towers are limited to a few days operation when the batteries run out. Then the infrastructure fails to over loads. Millions have been spent on "interoperability" and trunking radios...but they still can not communicate between agencies or even the various emergency departments at the local level. Hams CAN and WILL do it, but they need the frequencies.

Call you congress lizard NOW, and ask them to stop this nonsense...

BTW, I do know a little about radio, gps and the like and the filters, attenuators, antennas, pucks or software are not going to help...certainly not at a price you would be happy with.
 
sailaway78

sailaway78

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May 11, 2005
3,431
Seidelman S37 Slidell, La.
Military

I don't believe that the military will allow anything that could interfere with GPS. What with their navigation not to mention what that would do to a cruise missle's navigation. You would hear generals and admirals screaming like never before.
 
shemandr

shemandr

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Jan 1, 2006
7,076
Slickcraft 26 Sailfish
Nice N Easy said:
I don't believe that the military will allow anything that could interfere with GPS. What with their navigation not to mention what that would do to a cruise missle's navigation. You would hear generals and admirals screaming like never before.
Click to expand
I wish for this to be true.
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
The good news is that after the catastrophe and the batteries run down the GPS will work again and you will be able to talk on any band, ham or not, due to "emergency conditions"
Don't sell that sextant or LORAN. Yea, I know LORAN is dead, but you have to understand the military industrial complex. LORAN ain't dead it is just hibernating.
 
JVB

JVB

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Jan 26, 2006
270
Schock Wavelength 24 Lake Murray, SC
Nice N Easy said:
I don't believe that the military will allow anything that could interfere with GPS. What with their navigation not to mention what that would do to a cruise missle's navigation. You would hear generals and admirals screaming like never before.
Click to expand
Fortunately cruise missiles have the ability to navigate by comparing terrain "seen" below to onboard electronic maps. And I suspect they use inertial navigation units (which measure accelerations and turns) like those used in expensive airplanes and spacecraft. GPS is not the sole source of position data.

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

http://wiki.flightgear.org/index.php/Inertial_Navigation_System
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Even robot aircraft know to not use only one source of nav information!
 
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Gary_H

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Nov 5, 2007
469
Cal 2-25 Carolina Beach NC
I can tell you who is going to end up paying, the consumer. If there is mass interference then I would think a class action lawsuit would be close on the heals. Personally I can't afford to by all new GPS equipment nor should I be force to pay for any service packs, fiters or upgrades.
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
The article fourpoints posted is inaccurate. GPS satellites have a very narrow bandwidth and are "well behaved" outside that bandwidth. This is due to the regulations on "out of band transmissions" for satellites. Terrestrial bandwidth is not nearly as regulated. So the suspicion is that LightSquared will be broadcasting at high power in a band right next to the GPS band operating at low power. Any out of band transmission (there are ALWAYS out of band transmissions BTW) will be most felt near the band in question. This will result in a GPS receiver listening for low power transmission in the presence of a high power out of band noise environment. They were never designed to do that and will have problems discerning the low power GPS signals. Most of the GPS receivers that are not military spec have broad band antennas which will only make the receiver’s job harder.
Luckily there is a home brew narrow band antenna that can help. Unfortunately it will require some skills with a soldering iron to install the microwave amp in the antenna line.
Should also consider buying stock in the microwave amp company.
 
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Gary_H

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Nov 5, 2007
469
Cal 2-25 Carolina Beach NC
I'm glad there will be a fix but the point is if the problem was caused by lightsquared to existing operational equipment, would it not be their responsibility to provide the remedy (fix) free of charge to those that are affected? If not then in the end it will be the consumer who will end up with the time, expense and possibly burnt fingers fixing what someone else broke. Of course the government has said that they will not allow Lightsquared to proceed if there is an interference problem. So I'm not worried, we all know how we can trust the government to always look after our best interest ...right?
 
Roger Long

Roger Long

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Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Gary_H said:
Of course the government has said that they will not allow Lightsquared to proceed if there is an interference problem.
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It depends, as usual, on what you mean by "is". If the GPS manufacturers have been sloppy by letting their units listen across the "fence" line of the defined frequency bands and Lightsquared can keep their units rigorously on their side of the boundary, the FCC could well say there is no "problem". All new GPS units will simply be made to tighter tolerances and we will all be free to buy them.

If "is" means that the normal and inevitable bleed over between adjacent bands will create great danger to people like pilots and require replacement of an enormous installed base, then the FCC will tell Lightsquared that they will have to make their pool a bit smaller (see earlier threads).

I still fear the GPS manufacturers will make a lot of noise and then "reluctantly" settle for a solution that gives a lot of people a very strong incentive to buy a new GPS.

This shouldn't be a problem for most boaters as we are low to the surface and far away from probable antenna locations. The pilots with their GPS units that cost as much as a car and can't have Bill's signal booster wired in because of FAA red tape must be going crazy over on the aviation forums.
 
FourPoints

FourPoints

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Apr 8, 2010
1,606
Frers 33 41426 Westport, CT
Bill Roosa said:
The article fourpoints posted is inaccurate. GPS satellites have a very narrow bandwidth and are "well behaved" outside that bandwidth. This is due to the regulations on "out of band transmissions" for satellites. Terrestrial bandwidth is not nearly as regulated. So the suspicion is that LightSquared will be broadcasting at high power in a band right next to the GPS band operating at low power. Any out of band transmission (there are ALWAYS out of band transmissions BTW) will be most felt near the band in question.
Click to expand
unless I read it wrong, the guy was claiming that the problem is not out of band transmissions, but a lack of a signal filter on the receiver so that the receiver is picking up the transmission, even though they are not transmitting out of band.

RF signal (bandpass) filters are generally very large (and expensive) units that will not easily fit into most GPS installations (example of a 900mhz filter http://www.streakwave.com/Itemdesc.asp?ic=WR550-1002&eq=&Tp= A 1.5ghz filter would be a little smaller than this).

For decades the FCC has allocated white spaces between bands for the purpose of preventing adjacent channel interference, but in recent years they seem to be eliminating all white space and selling it off for cellular communications (where do you think much of the 700mhz stuff came from, it wasn't only TV station channels)

basically LightSquarred is saying the concept of white spaces is no longer needed, and any device designed to operate assuming a white space exists and fails to work if it doesn't, needs replaced.

Sunday I was heading down I-95 to my boat, it was a clear sunny day. My car GPS lost signal, didn't regain a lock for 10 miles. My girlfriend was down in DC for the weekend visiting one of her friends, and said she had problems Sunday with her GPS too...

I wonder if this is related to the problems sunday? Did anyone else experience GPS problems on Sunday?
 
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Gary_H

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Nov 5, 2007
469
Cal 2-25 Carolina Beach NC
It figures ..I just bought a new GPS chartplotter. I haven't even used it yet. I guess I'd better go somewhere this weekend so I will have gotten some use out of it before it's obsolete. Oh well there's still paper charts...and bread crumbs. Might be good time to learn how to use that sextant....chip log......and that compass thingy.
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
The problem is not white space specifically. Though the lack of it does not help. the band Lightsquared is operating in was reserved for low power space to ground communications so interference between the different satellites was pretty easy to handle. Now you have high power transmitters on the ground in a band "right next door" I don't care what they tell you no transmitter transmits exclusively in its band. There are ALWAYS out of band transmissions.
 
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