2006-02-08

NUMB3RS, GPS and Cell-Phones

I've been watching the last few episodes of the TV show Numb3rs. It is pretty good. It is nice to see a positive view of techy stuff on TV. We need to promote the sciences. And they do a very good job of not getting way too techy. If anything, they are pretty good at explaining some advanced math concepts so that an average person can get a feel for the concepts. I think I get to thank my sister for recommending the show :)

Watching the last episode, from this past Friday, I was taken a bit back. Here is a show that is trying to tech about the science of math, and they made a really careless error. They were talking about tracking a cell-phone. The cell-phone in question was used right near the investigators - and they say the GPS showed it was on campus.

The GPS? Cell phones don't have GPS! GPS isn't how they track where cell phones are!

They both use a similar methodology - triangulation. But a GPS receiver listens to 3 or more satellites in orbit to calculate it's position, and does not transmit anything.

A cell phone is tracked by what cell it is in - and if 3 cells can pick up a cell phone, that information can be used to triangulate the position of the cell phone. The ability was added mostly due to wanting to be able to pinpoint emergency calls.

The fact is that a cell phone does not have to make a call to be tracked. A cell phone will register itself when on to local cell towers. That is how the cell companies can immediately route a call to a specific cell-phone.

And more, this triangulation is being used for more than emergency use. Some cities are subscribing to cell-phone data to help track traffic. It seems many cars on the roads have cell-phones on board. Not making calls, just turned on. And they can use the data from the cell phones to calculate the speed of a significant fraction of the cars from this data. And they can tell when traffic is slowing or stopped - just because so many people have cell phones.

This is not the kind of mistake I would expect from a techy show. Of course, they would probably blame it on the fact that the character that said it is not one of the geeks.

It is interesting that people are worried that a GPS will rat on where they are, and never realize that their cell phone already does it. Yet a normal GPS cannot report on where you have been, unless you link it and download the data afterwards.

But there is a GPS device that does report back where you are. And it uses a cell-phone to report on you. The on-star system in 'select' GM cars. The core part of the on-star system is a GPS that uses an old analog cell-phone built in to report on your position.

And some rental cars are starting to have GPS units that can report in, either live, or as a report when you check-in.

Technology is wild. Big brother *is* watching! But what is he watching, and what is he doing with that data.

I noticed online that there is a horror movie coming out soon. It is based on GPS and geocaching - and is supposed to be based on a true story. I get the feeling that this will put a dark blotch on geocaching and GPS. Shame.

2 comments:

Stef said...

Eeek! Big Brother really is watching! Oh, my! Well, let him come find me!

I like that show, BTW, even though I never remember it's on until it's half over and am totally lost as to what happened before i tuned in.

Job search is going well, but no offers as of now.

And I've always wondered why I'm not on your blogroll...

Hope all is going okay with you. Talk to you soon-- Stef

Trinity said...

you're so techy geek keith ;)
xxx