[ntp:questions] GPS Jammers in Use by Criminals - Warping Time for Fraud Suggested

Chris Albertson albertson.chris at gmail.com
Thu Feb 23 04:38:48 UTC 2012

On Wed, Feb 22, 2012 at 6:01 PM, John Hasler <jhasler at newsguy.com> wrote:
> Chris writes:
>> A sophisticated jammer would know exactly when to transmit over one
>> bit or two bits, and in a narrow band just enough to corrupt the GPS
>> data and would have a very lower average power output.
> That would be a very sophisticated jammer indeed.  GPS is not narrow
> band.  It's spread-spectrum.

That depends on the time scale.  Over all it is wide because they have
to allow for all the doppler shifts but at any one instant in time a
spread spectrum is a narrow band radio.

You are correct that spoofing is harder.  But there is an example of a
really excellent GPS spoof in Iran.

My main point was that it should be easy to find an unsophisticated
jammer.   You might even place detectors where they can trigger
existing red-light enforcement cameras

> Spoofing it is much, much harder than
> jamming it (though not impossible for simple consumer-grade receivers).
> BTW jamming won't do a bit of good for the "time warping" fraud
> suggested.
> --
> John Hasler
> jhasler at newsguy.com
> Dancing Horse Hill
> Elmwood, WI USA
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Chris Albertson
Redondo Beach, California

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