(All below assumes a cellphone with no GPS tracking; I am assuming this because the searches are said to have been prompted by cell phone pings, and the search locations are all around the island. IMO, if her phone had GPS they would search in a different way)
http://searchengineland.com/cell-phone-triangulation-accuracy-is-all-over-the-map-14790
Ok, I have been reading about locating a person via cell phone pings. Cell phones are pinging whether you are using them or not. To get a really close location, you need three towers in the vicinity. (Thus the "cell phone triangulation").
For example: I have only 1 cell tower with a 4 mile radius. A ping can only indicate I am somewhere in that radius. Now, I have 2 cell towers. If they are far apart and their circles are seperate, it's just like having 1 tower. If, however their circles join, and both towers pick up the ping, then I am somewhere in the location where they both have signal. If I have three towers that ping me, now I can get REALLY close to the location- it's somewhere that all three join up. It's easier to see if you scroll down and look at the three circles in the above link.
Then there is the issue of whether or not the cellphone antenna is a directional antenna. If you have two towers that intersect WITH directional antennae, then the entire intersecting area doesn't have to be covered. This is also shown in the link, with two circles and the direction being represented.
What I would like to know is this: As you enter and go deeper into Sauvie, where are the cellphone towers and what is their radius? Are they using omnidirectional or directional antennae?
I want to know how close one can actually come to pinpointing that someone is on that island by cell pings.
Guess the only way to do that is to start googling the towers and their reception circles and map it out. If I ever get it all figured out I will post. I'm kind of hoping someone else here might have a map of all the local towers and their corresponding radii.
Here's a snippet of the article:
However, there are many places where there are fewer cell towers available, such as in the fringes of the cities and out in the country. If you have fewer than three cell towers available, pinpointing a mobile device can become a lot less precise. In cities where there are a lot more vertical structures which can be barriers to cell phone broadcasting and receiving, there have to be many more cell towers distributed in order to have good service. In the countryside, there are relatively fewer cell towers and a phone’s signal may be picked up only by a single one at much greater distance.
Those areas where a phone is only getting picked up by a single tower, and if it’s equipped with only omnidirectional antennae, the accuracy becomes even less.
