Hi If you run through the article the author claims that he's getting a few hundred feet of range with a few hundred mw of power into a good antenna.
Your cell phone and FM broadcast radio are equally susceptible under typical conditions. Bob On Nov 22, 2010, at 8:24 PM, scmcgr...@gmail.com wrote: > The Phrack article's jammer attacks the offset frequencies. > > Phrack.org/issues.html?issue=60&id=13 > > This article shows just how vulnerable L1 GPS is > > Scott > Sent from my Verizon Wireless BlackBerry > > -----Original Message----- > From: Magnus Danielson <mag...@rubidium.dyndns.org> > Sender: time-nuts-boun...@febo.com > Date: Tue, 23 Nov 2010 01:29:56 > To: <time-nuts@febo.com> > Reply-To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Subject: Re: [time-nuts] GPS jamming susceptibility > > On 11/23/2010 12:19 AM, Bob Camp wrote: >> Hi >> >> There is *very* little signal hitting the ground from a normal GPS bird. >> Even a few mili watts close at hand is going to be an enormous overload. The >> typical GPS does not use a lot of bits in the front end A/D. >> >> I suspect that if you tuned your little gizmo down to the FM broadcast band, >> it would take out your favorite FM station quite nicely. Same would be true >> of your cell phone if you tuned it there. Jamming from close by isn't all >> that hard to figure out, or to implement. There are switching power supplies >> that make wonderful jammers for low frequency signals. If it's RF, it can be >> jammed. The real question is can you jam it from a reasonable distance? > > There are a few reports and articles going into the susceptibility of > civilian receivers to jammers. Some public texts have also been written, > so the field is not completely covered only on green paper. > > A CW jammer will basically grab the AGC and as it gains down the CW the > GPS reception is gained down with it. In particular 1-bit receivers is > susceptable to this effect. 1,5-bit receivers with separate AGC > detection was developed and was able to combat the CW jammer situation. > The relative time when the code can control the bits quickly becomes > just a fraction since a sine spends long times in the extremes far away > from detection limits. > > Next thing to attack is lack of supression in the C/A code, and list of > offset-frequencies which is more susceptible can be found. > > Noise jammers is also possible. > > Things like these alongside the weak signal makes civilian receivers > quite sensitive, so quite a bit of line-of-sight distance can be jammed > with a fairly low output. > > Cheers, > Magnus > > _______________________________________________ > 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 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 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.
