[time-nuts] How hard is it to detect a GPS Jammer?

[Brooke Clarke]

Hi Hal:

Yes you can detect jammers driving by.

There was a prior case of unintentional GPS jamming around Moss Landing harbor, Monterey Bay, California caused by a 
faulty (oscillating) active TV antenna on a boat that was powered 24/7.

Military GPS receivers, like the DAGR or PLGR-II, include jamming detection.
http://www.prc68.com/I/DAGR.shtml#P2APPS

The patent Handheld GPS jammer locator
https://www.google.com/patents/US7233284
Contains some interesting info plus detailed plans for the hardware including mfg & model numbers, but not the Altera 
Model EPM7064STC44-10 FPGA code.  I suspect the FPGA not only does what's required for the patent to work, but also some 
other stuff like switching the LO to other frequencies (maybe both hi and lo side) so that it works not just for L1, but 
also all the GNSS positioning frequencies.  But you could use a micro controller to do the same thing for a one off unit.

What was not mentioned in the TED talk was how a US UAV was captured pretty much intact by spoofing a military GPS receiver.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

Hal Murray wrote:
> The recent discussion of solar flares screwing up GPS timing was interesting.
>
> I just watched Todd Humphreys TED talk again.  He's focused on location, but
> does mention time in terms of stock exchanges.
>    Todd Humphreys: How to fool a GPS
>    http://www.ted.com/talks/todd_humphreys_how_to_fool_a_gps.html
>
> He's got a good discussion of GPS jammers and spoofers, but no geeky details.
>
>
> What's the spectral/power output of the typical eBay GPS jammer?
>
> Suppose I lived near a major highway.  Could I build a receiver that would
> count jammers driving by?  Could I track them (at least somewhat) with a
> directional antenna on a rotator?
>
> Is this something semi-geeky amateurs could contribute to?
>
> What sort of gear has harmonics in the GPS band?
>
> ------
>
> I assume people are familiar with the trucker who jammed the FAA test in NJ.
> Here is a good story:
>    http://www.insidegnss.com/node/3676
>
> That article has a link to commercial gear targeted at this market.
>    http://www.exelisinc.com/solutions/signalsentry/Pages/default.aspx
> The graphics shows 3 receivers is a port/harbor setting.
>
>
>