Re: [time-nuts] ***SPAM*** How hard is it to detect a GPS Jammer?
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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ***SPAM*** How hard is it to detect a GPS Jammer?
On Sun, Oct 06, 2013 at 09:59:50PM -0700, Hal Murray wrote: 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? I would think this would be a natural task for one of the SDR setups like the USRP and gnuradio... and using the more sophisticated MIMO versions of the USRP and a suitable DF antenna array of GPS antennas you could use correlation interferometry to get a pretty good bearing on a passing jammer (no mechanical rotating antenna needed). Use a couple of these in a suitable relationship to the road and you probably could locate the vehicle in question and capture video of it. Might be some quite interesting statistics near an interstate with heavy truck traffic. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ***SPAM*** How hard is it to detect a GPS Jammer?
On 10/7/13 4:51 PM, David I. Emery wrote: On Sun, Oct 06, 2013 at 09:59:50PM -0700, Hal Murray wrote: 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? I would think this would be a natural task for one of the SDR setups like the USRP and gnuradio... and using the more sophisticated MIMO versions of the USRP and a suitable DF antenna array of GPS antennas you could use correlation interferometry to get a pretty good bearing on a passing jammer (no mechanical rotating antenna needed). Use a couple of these in a suitable relationship to the road and you probably could locate the vehicle in question and capture video of it. Might be some quite interesting statistics near an interstate with heavy truck traffic. AN excellent project for a student. You could make a nice senior project or Master's thesis with this. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] ***SPAM*** How hard is it to detect a GPS Jammer?
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. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
