How does 4G conflict with GPS?

4G or 4th Generation uses the same frequencies already in use by cell phones. The difference in generations - very simply speaking - was going from analog to digital, then increased speeds for digital data. It didn't involve "new" frequencies.

One company has received a conditional waiver from the FCC to build a new network in the same frequency band used by the GPS satellites to provide high speed broadband data services using the same transmission types which will be used by cellular companies. That transmission type is LTE which the cell phone companies call 4G. The new network will not use satellites but ground based transmitters and their signals will drown out the GPS satellite frequencies.

never heard about this issue before.

and the gps companies are not up in arms about it?

The proposed lightsquared systems are to operate in the frequency band adjacent to the GPS (L1) signal.

It's the "adjacent" that causes problems.

The transmitters lightsquared (or anyone else for that matter) will use will end up splattering some signal outside of their designed frequency range. There are FCC limits on how much of that splatter is allowed.

On the GPS side, while modern GPS receivers have filters on their front ends, for the most part those filters aren't very sharp. The sharper you make a filter, the more expensive it becomes, and the more loss and distortion it introduces into the system.

GPS receivers are already working with very weak signals -- below the noise floor in fact, only picking up signals using pretty amazing correlation techniques.

That makes GPS receivers particularly susceptible to splatter from those adjacent frequencies.

With my fixed-location GPS antenna used for timing and frequency reference, it would be easy (no, it would be a pain in the * and expensive) for me to add a collar to the antenna so it would not "see" any signals within 20 degrees of the horizon; that would most likely eliminate interference from ground-based systems.

Mobile/portable and particularly airborne GPS systems do not have that luxury of shielding the antenna.

Other solutions are to make lightsquared drastically reduce emissions in the GPS band, or render obsolete (unusable) a whole lot of existing GPS receivers.

Does this mean our current GPSr's are gonna be junk?

When the Lightsquared project is built (yes I did say WHEN), your GPS will most likely be useless in urban and suburban areas where they plan to rollout the terrestrial transmitters. When you are near one of their transmitters, your GPS will most likely lose signal lock.

The article at http://www.gpsworld.com/gnss-system/news/data-shows-disastro... gives an overview of the test results and a comparison of consumer grade device degradation versus commercial device degradation. The consumer devices actually fare a bit better as they are not as sensitive as the commercial equipment. In the rural areas it should not be as big a problem because Lightsquared intends to use satellites to cover the vast areas as it would be prohibitively expensive to cover rural areas with transmitters. Right now when you are in various rural areas you have no cellular coverage because building cell towers in those low population density areas would cost more than the return. Lightsquared solves that using satellites and avoiding tower construction in those areas.

I'm up here in Canada so (when/if) this becomes a reality I suspect Canada will be years behind in this technology so it won't be a pressing issue.

Unless Industry Canada gets stupid and decides to follow the FCC's lead in reallocating the L1 band, Canadians are safe. The ground based transmitters will not have the range to effect Canada except for perhaps urban/suburban border areas like Buffalo/Fort Erie, Niagara Falls, Detroit/Windsor, etc. Toronto, Ottawa, Montreal, Victoria, etc. would be safe.

Good news is if my 765T becomes useless in my area here on Long Island, I can always give it to my sister living in Mississauga. She already has my C550.

Thanks for the info. I never cease to be amazed at the amount of knowledge that this forum has if you just ask.

It never ceases to amaze me the way our government continues to make such stupid decisions. This is likely based on the fact that someone in government is going to make a truckload of money out of the deal.

You are too kind to our FCC. It is unfortunately a combination of stupid and money grubbing.

The FCC has been selling freq allocation for many years now and the current set of bosses at the FCC are technically not savvy and want the income from sales of allocations.

They are the same ones that tried to make broad band over AC lines to pollute the HF spectrum.

It is not so much splatter onto adjacent uses like the GPS as it is too close of frequencies to enable even the best of GPS receivers to not be desensed and loose signals. It used to be the FCC would test this themselves. Now they let the fox guard the chicken coop and tell them there are no chickens missing at the end of the day!

The FCC is not doing it's job and is violating even its own rules! Your tax dollars at work!

Jaydub

As usual, our Governments hard at work to give more to the cell companies.

This news makes me a tad bit angry!!!

Only a 'tad'? Maybe that's why this shyte happens. You ain't gettin' mad enough!

quote=Juggernaut Only a 'tad'? Maybe that's why this shyte happens. You ain't gettin' mad enough!

True Fact.
Here's the first step- look here to find out who your reps are, and then email them.

IMO, Tell them that what you wanted for broadband access to ALL citizens was affordable and available service WITHOUT sacrificing something else like TV (done..garbage reception in low and object-cluttered areas) and your GPS reception.

The driver for all of this is because we bite in comparison to other countries for high speed internet access. (see this and this.

The only problem is that FOR SURE someone at the FCC will benefit by tipping the advantage to the wireless/cable/telco industries and NOT the consumer, imo.