Re: Detecting IEDs...


"Randy Poe" <poespam-trap@xxxxxxxxx> wrote in message
news:1193507282.959862.49910@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Oct 27, 10:45 am, "Tom Potter" <tdp1...@xxxxxxxxx> wrote:
"Sam Wormley" <sworml...@xxxxxxxxx> wrote in message

news:JptUi.172822$Fc.143347@xxxxxxxxxxxx

Tom Potter wrote:

And it would be a piece of cake
to build a device that:

1. Monitored the cell phone band.

Potter, since the signal is so weak at the GPS receiver antenna, a
single
small transmitter can "render unusable" all receivers over a large
area
(many hundreds of square km).

Sammy, reread my post, Randy Poe's post,
and the patent I referenced,

and get educated why "Jamming"
as you previously referred to it,

is not an effective way to
neutralize GPS weaponry.

Do your homework and get educated on why "Jamming"
is such an easy way to neutralize GPS receivers.

http://computerworld.com/securitytopics/security/story/0,10801,77702,00.html
"January 17, 2003 (Computerworld) -- Government officials and
communications experts are assessing the public safety and
security implications of a newly posted online article that provides
directions for making cheap devices that can jam Global Positioning
System (GPS) signals."

http://www.avweb.com/news/avionics/182754-1.html
"You think the only time you have to worry about getting your GPS
jammed is during wartime? Think again -- these devices are so
sensitive that many things could jam them."

http://www.theregister.co.uk/2007/06/06/mod_gps_jamming_trial_cornwall/
[an experiment in GPS jamming by the UK Ministry of Defense]
"According to a BBC report, effects on GPS receivers can be expected
up to 11km from Portreath"

- Randy

Randy, do you ever read your references?

I challenge you to post actual quotes and data
from these sites that supports your position.

Here is an excerpt from the patent I mentioned.
================
"Description of the Related Art

In recent years, multi-element antenna systems have proven themselves to be
extremely effective at protecting GPS receivers from high power jamming.
High dynamic range systems with digital back-end processing, such as those
developed at Rockwell Collins, Inc., are capable of spatially nulling
jamming signals by as much as 60 dB while simultaneously maintaining good
antenna gain to desired signal sources.

Recently, however, there has been renewed interest in C/A code spoofers and
repeaters (meaconers). A spoofer is a broadcast signal intended to look like
a GPS satellite signal."

Randy, note that proper techniques are
"extremely effective at protecting GPS receivers from high power jamming",

but that there is a
"renewed interest in C/A code spoofers and repeaters (meaconers)."

An ad for a commercial "jammer" is listed below.
Note that it takes 1000 Milliwatts ( One watt)
of RF power to jam receivers about 50 feet away.

And note that the power spreads out as a function of
the square of the distance, so it would take
4 watts to jam a receiver 100 feet away,
16 watts to jam a receiver 200 feet away,
64 watts to jam a receiver 400 feet away, etc.

Ad for a GPS Jammer.
==============================
Big Power GPS Jammer
Description:
Total Output Power: 1000 Milliwatts
Effective distance: 0 to 15 metres (in optimum conditions)
===================

--
Tom Potter

http://home.earthlink.net/~tdp
http://notsocrazyideas.blogspot.com/




.

Relevant Pages

  • Re: Detecting IEDs...
    ... Output Power - 4 W ... "EFFECTIVELY DENY USE OF GPS" ... Monitor all cell phone spectrum signals in the area. ... "Sammy, if I were trying to jam nearby GPS receivers, ...
    (sci.physics)
  • Re: Detecting IEDs...
    ... Jamming is a very effective way to neutralize GPS, ... extremely effective at protecting GPS receivers from high power jamming. ... "extremely effective at protecting GPS receivers from high power jamming", ...
    (sci.physics)
  • Re: L2C and other signals
    ... I am wondering whether the new gps signals will replace the oldies. ... what's the critical number of l2c transmiting satellites for seeing ... After 2020, legacy dual frequency receivers may still work, but the DoD would no longer assure that Ppower levels and the navigation message would remain the same. ... Just the United States CORS (Continually Operating Reference Stations) network alone comprises more than 1,000 receivers. ...
    (sci.geo.satellite-nav)
  • Re: for photography
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    (sci.geo.satellite-nav)
  • Re: Detecting IEDs...
    ... sensitive GPS receivers at the L-band frequencies. ... take much power to jam the signal. ... jamming signals by as much as 60 dB while simultaneously maintaining good ...
    (sci.physics)