[PW] GPS- stalking?

[jtg]

Again two angles:

A straight GPS receiver is passive, and it emits no greater electronic
signature than an IPod or similar device (and is about the same size). They
have varying memory capacities to store waypoints (notes of position/time).

Should someone want to know where you have been over a particular time
period they would need to secrete in your vehicle, say, a GPS set to
auto-store at a suitable interval, then later retrieve it and plot your
movements. The accuracy of the plot would depend on the time period and
number of waypoints storable. Whether this works at all depends on the
satellite signals being received by the unit: the car itself could well
block them as they are very weak and up in the Ghz. Tall buildings will
block them as well. The result would probably give a good idea of whether
someone visited a certain area in a town or city, but not whether they
stopped for a few minutes along a major road. The only way to detect
something like this is a physical search as for a bomb: given that the
device would need to be easily both placed and retrieved, the options are
fairly limited.

The other angle is active tracking where the GPS is attached to or
integrated with a transmitter. Then you have to detect the transmission
using a field-strength detector and frequency analyzer. Since the
transmission is entirely independent of the GPS frequency and could
conceivably be infra-red or ultrasonic, also since no physical retrieval is
needed and so the hiding place can be more sophisticated with a remote
antenna, it's time to call in the Spooks!      



HTH

John Germain

Jersey
British Channel Islands
-----Original Message-----
From: project-wombat-open-bounces at lists.project-wombat.org
[mailto:project-wombat-open-bounces at lists.project-wombat.org] On Behalf Of
sylvia ryals
Sent: Friday, October 05, 2007 9:45 PM
To: list at project-wombat.org
Subject: [PW] GPS

Since GPS devices are sometimes hidden and used to
stalk victims, what would it require to detect a
hidden one?

Sylvia

~~~
Namiko wrote:

Date: Thu, 4 Oct 2007 14:48:22 -0700 (PDT)
From: NS <sop2nd at yahoo.com>
Subject: Re: [PW] ? cell phone GPS
To: list at project-wombat.org

I think this depends on whether you're talking about
GPS or A-GPS.
Here's a quick overview of A-GPS:
http://www.globallocate.com/A-GPS/A-GPS_Frameset.htm

and of course, Wikipedia has an entry, with an
explanation of how the
system works: http://en.wikipedia.org/wiki/A-GPS

A-GPS is basically a bare bones locator that really
never turns "off"
unless the phone is off or the battery is dead, I
think, although
some handsets (like feature-rich smartphones and PDAs)
will allow you
to choose whether you want to turn the locator off and
go to
"emergency only" mode. 

A-GPS also works without the use of a SIM card; the US
uses both GSM
(like AT&T and T-Mobile) and CDMA (like Verizon and
Sprint) networks.

Namiko



       
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