[Discuss] GPS feature in cellphones?

[Bill Ricker]

On Fri, Jun 6, 2014 at 11:56 AM, Bill Bogstad <bogstad at pobox.com> wrote:

> 4. GPS can be done passively by anyone anywhere, while cell tower
> triangulation requires endpoints that transmit (and as a result
> identify themselves.)
> I think that #4 is particularly interesting.
>

​Depends what you mean by "passive".
   Tower triangulation does not require cooperation of the device being
tracked, just correlation of its registration chirps, but doesn't let the
device know its location.
    GPS does not require transmission for the device to compute the
device's location (Navigation display), but requires a transmission to have
anyone else see it (GPS tracking devices, E911).



-- 
Bill Ricker
bill.n1vux at gmail.com
https://www.linkedin.com/in/n1vux