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Does the GPS on your cell phone work?

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Skud

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Does the GPS on your cell phone work?
Target 8 checked different models, places

Updated: Thursday, 03 Nov 2011, 11:00 PM EDT
Published : Thursday, 03 Nov 2011, 11:00 PM EDT

By Ken Kolker

GRAND RAPIDS, Mich. (WOOD) - It's big news when it works -- cell phone signals leading police to overturned boats, to lost and injured deer hunters, to fleeing thieves, even killers.

But the technology couldn't pinpoint 3-year-old Ethan, who recently called 911 from a cell phone at his home near Sparta.

Does the GPS on your cell phone work? | WOOD TV8
 

tampabaynews

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When I was in dispatch, I had this problem several times with certain carriers. One that comes to mind is MetroPCS. A lot of times it will show the nearest tower, but not the actual location. And the process involved to get the carrier to try to ping a better location or give you the residential address of the owner takes 30 mins to an hour.
 

fineshot1

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Its common sense that any cell phone service provider networks that depends
on a cell phones ability to receive gps signals is going to have limitations
when a cell phone calling 911 does not have line of site to the satellites
over head.

Some cell phone networks also use a triangulation method between 3 or more
cell sites and this can work much better in a situation where the calling cell
phone has no line of site over head.

I am not sure which cell service providers use which methods so i can not
comment on that.
 

ff-medic

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And the process involved to get the carrier to try to ping a better location or give you the residential address of the owner takes 30 mins to an hour.

I thought most cell carriers wanted a warrant before giving out that information. A warrant which requires an affidavit before hand that states why the information is needed.

There was an uproar about this, as I read about a year ago, by most cell phone companys. No warrant, no GPS location.

FF - Medic !!!
 

ff-medic

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Its common sense that any cell phone service provider networks that depends
on a cell phones ability to receive gps signals is going to have limitations
when a cell phone calling 911 does not have line of site to the satellites
over head.

Some cell phone networks also use a triangulation method between 3 or more
cell sites and this can work much better in a situation where the calling cell
phone has no line of site over head.
Satellites overhead?

As I have noticed " In my area". Most cell phone towers have three antennas : 120 degrees apart. reading the ESN ( Electronic serial number ) , could they not determine the signal strength to determine aproxmate location?

Could not two towers alone triangulate a location of a cell? I am not a cell phone / tower expert, but it appears that two towers, could give a good location of where a cell phone is. One tower could very well get you in an aproxamte area, especially if used with a mapping program, a regular county - city - state map and good deduction and theory, or simply google earth?

Time and distance traveled between two or more towers, before the incident ( lost person, car wreck ), and determining location using cell phone records seem very probable to me.

FF - Medic !!!
 
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tampabaynews

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I thought most cell carriers wanted a warrant before giving out that information. A warrant which requires an affidavit before hand that states why the information is needed.

There was an uproar about this, as I read about a year ago, by most cell phone companys. No warrant, no GPS location.

FF - Medic !!!
A warrant would be necessary if an agency needed the GPS information to press criminal charges on a caller.

In an emergency where the caller may be in grave danger, almost all carriers I dealt with only require a form. It is filled out by the call taker, signed by dispatch supervisor, and faxed to the provider. Usually we'd get a response in 30 mins to an hour.

I used this once on a kidnapping call. Smart victim put his phone in his pocket so I could hear the perps in the background until the line went dead a few minutes later. Bad thing is he had a crap MetroPCS phone so I couldn't get his location without going through the provider. We went through the process and they gave me his location in a half an hour. We went out to the location and found him tied up in his trunk.
 

fineshot1

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Satellites overhead?

As I have noticed " In my area". Most cell phone towers have three antennas : 120 degrees apart. reading the ESN ( Electronic serial number ) , could they not determine the signal strength to determine aproxmate location?

Could not two towers alone triangulate a location of a cell? I am not a cell phone / tower expert, but it appears that two towers, could give a good location of where a cell phone is. One tower could very well get you in an aproxamte area, especially if used with a mapping program, a regular county - city - state map and good deduction and theory, or simply google earth?

Time and distance traveled between two or more towers, before the incident ( lost person, car wreck ), and determining location using cell phone records seem very probable to me.

FF - Medic !!!
yes - satellites overhead - you know those orbiting devices that provide GPS signals
so that your cellphone can supply a GPS location on a 911 call(or any call for that
matter).

The triangulation technologies work most accurately with a minimum of three cell sites
involved in the process. As a fire fighter medic I am sure you know it does not help if
a medic gets dispatched to a location around the block from where it is needed.

I think you mean each cell site has 3 "sectors"(not antennas). Each sector covers a 120
degree direction. In each sector I have seen some cell sites with 2 or 3 directional panel
antennas and also for triangulation purposes each cell site sector has an additional
antenna near the top of the tower - a sort of a (not sure how to describe it) patch antenna
which is used to help in finding the exact direction. Combined with software and signal
processing in the network all working in unison together to provide a pretty accurate
location which I have heard claims of being within several yards of the actual incident
location.

I worked in the cellular network industry from 1990 - 2000 for two different providers and
when I left most of this technology was just being developed and is in service now.
 

ff-medic

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I think you mean each cell site has 3 "sectors"(not antennas). Each sector covers a 120
degree direction. In each sector I have seen some cell sites with 2 or 3 directional panel
antennas and also for triangulation purposes each cell site sector has an additional
antenna near the top of the tower - a sort of a (not sure how to describe it) patch antenna
which is used to help in finding the exact direction.

In my area, I have only noticed the three antennas on top the tower - which are tan or creme colored, thin and tall. They are about 120 degrees of each other - ??? direction = North - Southeast and Southwest. Some towers have the three tan / creme antennas, and tall whip antennas on top, possibly with a microwave antenna on the tower ; about ?? 25 feet below the cell antennas.

Microwave on a cell site is beyond me, unless it is for data transmission , maybe a public safety agency has some antennas on top. Again, I am not a cell site expert, I only have limited knowledge.

FF - Medic !!!
 

fineshot1

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Microwave on a cell site is beyond me, unless it is for data transmission , maybe a public safety agency has some antennas on top. Again, I am not a cell site expert, I only have limited knowledge. FF - Medic !!!
The microwave antennas are for cellular network voice/data back haul to the local cellular switch
where ever that may be located. Some cellular service providers use microwave and some do not.
If they do not, then they use a combonation of T1/T3 terrestrial circuits provided by the local
telephone company or companies in the area.

The cell site equipment itself does not route calls, but routes the call voice and data to the local
cell switch which in turn routes calls to the local PSTN or the long distance carriers like AT&T
or SPRINT or whomever.

Cellular network systems are usually very complex.
 

mikewazowski

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If they do not, then they use a combonation of T1/T3 terrestrial circuits provided by the local
telephone company or companies in the area.
T1/T3 is pretty old technology. A lot of sites are fed with GigE via fiber from any number of fiber providers

The cell site equipment itself does not route calls, but routes the call voice and data to the local
cell switch
With LTE, eNodeB's can talk to each other.

If your familiar with UMTS, the RNC has been removed and the eNodeB's
now perform this function.
 

zz0468

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...and also for triangulation purposes each cell site sector has an additional
antenna near the top of the tower - a sort of a (not sure how to describe it) patch antenna
which is used to help in finding the exact direction.
I've never heard of this. Are you sure it's not a GPS antenna? Cell sites use GPS for timing.
 

fineshot1

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T1/T3 is pretty old technology. A lot of sites are fed with GigE via fiber from any number of fiber providers



With LTE, eNodeB's can talk to each other.

Mike - this is not an a to z list of all cellular network capabilities.

For the sake of keeping it simple for a newbie i left out many things
that are not relevant to this thread.

If your familiar with UMTS, the RNC has been removed and the eNodeB's
now perform this function.
I've never heard of this. Are you sure it's not a GPS antenna? Cell sites use GPS for timing.
I am well aware of how cell sites acquire their timing. These antennas I referenced are
NOT gps antennas. I'll see if i can find a pic of them and post it.
 

mikewazowski

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Many cell sites use timing derived from incoming transmission from the switch.

None of the cell sites I have ever worked at or seen have any antennas used for triangulation except for the regular cell antennas.

Never once has this triangulation antenna been mentioned in any if the Ericsson training sessions I have attended.
 

mikewazowski

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They are about 120 degrees of each other

FF - Medic !!!
That would probably be a 3 sectored site although many antenna manufacturers now make an antenna that provides two or more beam widths that allow an antenna to cover more than one sector. Those 3 antennas might actually serve a six sectored site.

There are also omnidirectional one sectored sites which are generally found in rural areas.

2 sector sites can sometimes be found along highways shooting the signal up and down the highway where the population on either side of the highway is low.
 

fineshot1

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Many cell sites use timing derived from incoming transmission from the switch.

None of the cell sites I have ever worked at or seen have any antennas used for triangulation except for the regular cell antennas.

Never once has this triangulation antenna been mentioned in any if the Ericsson training sessions I have attended.
Mike - I never said Ericsson used this technology and I do not know what they use,
but its strange that you mentioned this because Ericsson filed many patents back
between 1994 and 2000 (and perhaps after) developing triangulation methods which
I remember reading up on some of them. I think the antenna I am referring to is a
phased array panel of some type but its been a few years so I don't recall exactly
and again I'll post a pic if I can locate one.

I know that when cell sites were analog they used timing from the switch via the
T1 circuits but I am pretty sure once they all went to CDMA, TDMA, GSM, etc
they switched to the gps received timing standard. Every cell site I have been to
in many years has had (for each cell provider) a base station gps antenna mounted
somewhere close to the base of the tower or if a building top somewhere just outside
the cell site - see link below of typical base station gps antenna. This antenna would
feed a gps timing standard and that would distribute to the base station equipment.
This is also typical of simulcast trunk systems.

GPS0015 Base Station GPS Antenna
 

mikewazowski

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I know that when cell sites were analog they used timing from the switch via the T1 circuits but I am pretty sure once they all went to CDMA, TDMA, GSM, etc they switched to the gps received timing standard.
TDMA and GSM was generally timed off a T1 as well although GSM could use an optional GPS reference at the base station.

I believe most carriers that went CDMA used a GPS reference at the base station and as you said, typically mounted on the shelter or about 10 feet up the tower.

UMTS and LTE do not require GPS at the base stations.

As I'm typing this, I've got 3 RBS2000 GSM cabinets and 1 RBS3000 UMTS cabinet (all Ericsson equipment) within reach.

The 3 6000 series UMTS units are a couple of racks away and out of my reach.

This site actually does have a GPS reference but that is only used for the pre-Wimax equipment installed here.

The 2G/3G equipment does not connect into that reference at all.

The only other non-wimax sites that have a GPS antenna are the paging simulcast sites.

Time to get back to work.
 

zz0468

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I know CDMA requires GPS timing, and it transfers that timing to the handset. In fact, there are time standards available that get their primary signal from a CDMA cell site, because GPS-quality timing is passed through to the CDMA carrier.
 
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