A friend was telling me that some Nav units (in the Pacifica) use cell towers instead of satellites as the points of referance. I haven't done much research but the little I did I found nothing to collaborate this. Any members here have details on how the GPS works in the jeeps. I thought all GPS and Navagation systems worked using satellites. I know that cell phones now need to be traceable incase of emergancies, which seems to ad a little merit to his comment.

Not really sure where your friend gets his information, but it's wrong.

For one thing, I have a hard time getting tower on my cell phone, so why in the world would anyone even consider using cell towers to pinpoint location. Also, if cell towers can pinpoint location, then why in the world do you need to have GPS inabled phones in order for authorities to find you in an emergency?

Didn't ask where he got it just thought I would try and look into it. Not knowing where u live I can't atest to your signal strength but I have pretty good signal strength where I am. Haven't dropped a call in along time. I agree with u on the GPS/cell not working in areas with no connection where as satellite, location should not be a problem which is why I thought I would ask u guys as this is a popular thread and alot of the SRTs have the Nav systems installed in them and u would know. I also don't think that cell phones need to be GPS enabled in order to find the location of the phone. They use triangulation between 2 - 4 towers the more towers the more accurate the final location. My friend bought the Pacifica but did not buy the Nav option because for some reason he thought that they used cell tower and thus it would not have the accuracy or even work all the time. He has a Garmin or something that he uses and it is dead nuts accurate. What does the owners manual say about the Nav units in your vehicles?

What does the owners manual say about the Nav units in your vehicles?
They go off of satellite signals, nothing else.

Thank you, I thought as much.

If it's GPS it uses satellites alone for location. The receiver needs a signal from 3 satellites for positioning and a 4th if you want to know your altitude as well.
As a side note, many automotive GPS units incorporate a logic module that allows the nav. unit to continue to display vehicle movement & location in the event you lose satellite reception for a short time. This "logic" uses the onboard speedometer, compass, etc. to keep the GPS screen scrolling without satellite info but it is capable of predicting only an approximation of your location.

How do you explain my cell phone with navigation that does not work with the satelites.As long as I stay on line it will take me anywhere I want to go.I can't get over this $29.00 samsung cell phone that does almost as much as my $1800. nav in my GC.I use it all the time when I'm driving my other cars.
It has to be using the towers to be as accurate as it is.

gps equipped phones use the cellular network they are running on for gps information. Usually a combination of cell tower triangulation and gps information based upon cell tower coordinates. Not the same as portable gps units that actually receive their information from satellites. I prefer the portable gps units. I have a Garman I use for geocaching. I've used it on airplanes and logged my flight data. You can't do that with a cell phone. Also, if you have no cell service, it's good to know where you are which you can get from your Jeeps Nav unit.

How do you explain my cell phone with navigation that does not work with the satelites.As long as I stay on line it will take me anywhere I want to go.I can't get over this $29.00 samsung cell phone that does almost as much as my $1800. nav in my GC.I use it all the time when I'm driving my other cars.
It has to be using the towers to be as accurate as it is.If your cellphone offers navigation it DOES work with the GPS satellite network, period. The towers are only used to transmit the maps. Your phone's GPS receiver gets the satellite info & transmits the location to the cell tower & the maps are generated & sent back on the tower network to your phone. The key is that your location is determined inside your phone using coordinates generated from the GPS satellite network.
Your phone is 1/2 of a hand held GPS unit. It receives the satellite signal exactly the same way it simply has no built-in map database. The mapping is done on the phone companies side & sent back to your phone.

Thank you very much.That is what is so great about these forums.I don't even like to talk on these little cell phones,but when they offered me this one with the navigation I thought that was great.Now I know how the work.Thanks again.

"Most phones with "GPS" in fact use A-GPS technology. The "A" stands for assisted, and means that the phone relies on the network for help in determining location. Although the phone does receive GPS signals directly from the satellites, it can't determine actual location without help from the cell network."

From Phonescoop.com

Thx for all the input guys now all I have to do is buy a GCSRT8, Can't wait:) .

They go off of satellite signals, nothing else.

well.... a lot of GPS units are equipped with DGPS and/or WAAS which are systems that use land based transmitters to increase accuracy.
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