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

David Woolley david at ex.djwhome.demon.invalid
Thu Feb 23 08:05:50 UTC 2012

Chris Albertson wrote:

> 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.

It is direct sequence, not frequency hopping. I think the spread 
spectrum is more to do with interference rejection and coding gains. 
The significance of Doppler is that it rules out frequency division 
multiplexing.  For the L2 signal, it is also a question that the 
chipping code is cryptographic.  The chipping codes for L1 are 
published, so a consumer GPS signal could be completely spoofed.

> 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

I think the news items originate from press releases about a study that 
involved installing a network of jammer detectors and suggesting the 
best places to put them (although only really in relation to stolen 

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