On 10/6/13 9:59 PM, 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?
There were a series of articles in GPSWorld last year(?) that described
test on some jammers. For the most part, swept VCOs, as I recall.
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?
Yes..
Or do what real sigint receivers do, use multiple antennas less than a
have wavelength apart and interferometry to do direction determination.
Is this something semi-geeky amateurs could contribute to?
Yes, but more in the long term policy sense. you could measure the data
and publish a paper saying "here's what the jammer incidence is".
It's not like you could say "I detected a jammer, and it appears to be
coming from license plate ABC 123". I suppose you could send such data
to the FCC, but I don't know that they have a good ingest mechanism.
What sort of gear has harmonics in the GPS band?
Poorly operating TV antenna booster amplifiers are notorious, as are
some plasma flat screens.
------
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.
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