MossRoad
Super Moderator
- Joined
- Aug 31, 2001
- Messages
- 65,366
- Location
- South Bend, Indiana (near)
- Tractor
- Power Trac PT425 2001 Model Year
From what I've read, there's PINGing and Triangulation.
PINGing the phone means the cell phone company asks the phone where it is. The GPS on the phone finds its coordinates, and sends it back to the cell phone company. That only requires one tower and a phone with GPS in it.
Triangulation requires three towers, and it compares signal strength and time delay to find the location of the phone. Doesn't need GPS, but does need a couple towers, three or more is better.
I don't think the local 911 dispatch anywhere could actually PING anyone's cell phone for location in the past. I believe they had to contact the cell phone company to do the PING for them, and that eats up valuable time. Same thing with triangulation. However, I also recall reading something about E911 that transmits the GPS data in the 911 call directly to the 911 center, so that may indeed bypass the need to contact the cell phone company.
As in the case of my in-laws' house, there is only 1 cell tower that they can hit from their house, and it is located a couple miles away in another time-zone. Cell phones at their house will frequently be off by an hour if auto-set isn't disabled. They also have an old flip-phone. It doesn't have GPS. So they'd be out of luck with no GPS phone and only one cell tower. They won't upgrade their phone, so we insist they keep their land-line. Parents!
PINGing the phone means the cell phone company asks the phone where it is. The GPS on the phone finds its coordinates, and sends it back to the cell phone company. That only requires one tower and a phone with GPS in it.
Triangulation requires three towers, and it compares signal strength and time delay to find the location of the phone. Doesn't need GPS, but does need a couple towers, three or more is better.
I don't think the local 911 dispatch anywhere could actually PING anyone's cell phone for location in the past. I believe they had to contact the cell phone company to do the PING for them, and that eats up valuable time. Same thing with triangulation. However, I also recall reading something about E911 that transmits the GPS data in the 911 call directly to the 911 center, so that may indeed bypass the need to contact the cell phone company.
As in the case of my in-laws' house, there is only 1 cell tower that they can hit from their house, and it is located a couple miles away in another time-zone. Cell phones at their house will frequently be off by an hour if auto-set isn't disabled. They also have an old flip-phone. It doesn't have GPS. So they'd be out of luck with no GPS phone and only one cell tower. They won't upgrade their phone, so we insist they keep their land-line. Parents!
