See my earlier post. Briefly: Antennas do not have an infinite front-to-back ratio. (<40 dB)
The path loss from a surface jammer to a plane (10 miles) is many, many dB less than from plane to bird (15,000 miles). -John ============ > Considering that the GPS antenna in aircrafts is mounted on top of > fuselage, > and that its radiation pattern is upward, it seems that a ground jammer > will > have an uphill battle. > > > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on > Behalf Of J. Forster > Sent: Sunday, November 15, 2009 6:28 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] The Demise of LORAN (was Re: Reference > oscillator accuracy) > > > Or even into MP3 players, iPods, laptops, or cell phones. Then they'd > wander all over the place too. With the latter two hosts, they could even > be controlled remotely and even be fairly powerful. Would you notice > having to recharge your battery a bit more often? > > -John > > =========== > > >> Magnus Danielson wrote: >>> Chuck, >>> >>> Chuck Harris wrote: >>>> What makes you think it needs to be CW, and cannot be pulsed and >>>> chirped? >>> >>> May I roll in a noise jammer into the debate? >> >> Absolutely! They can be extremely power efficient. Raise the noise >> floor in the vicinity of the receiver, and it is all done. >> >> Probably the easiest solution would be to take a PN source and use it >> to drive a pulser that pulses a chirp oscillator. If you are feeling >> really polite, you could put a bandpass filter on the thing to protect >> other services. >> >>>> All it has to do is confuse the receiver enough so that you can't >>>> trust its readings. >>> >>> Depends on the goal. For some strategies, blackout is the goal, for >>> some >>> getting the readings go haywire every once in a while suffice. >> >> Agreed! >> >> My 9V battery suggestion was for a localized blackout device. You only >> have to make the receiver question each satellite's signal often enough >> for it to rule it out. No way is CW necessary, or even desirable. >> >> As John suggested, someone (say the Chinese) could put these things in >> battery operated stuffed animals, and set them up to jam a little bit >> now and then. After Xmas, the GPS landscape would be littered with >> these >> little stealth jammers, and willing supplicants to replace their >> batteries. >> >> -Chuck >> >> _______________________________________________ >> 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. > > > > > E-mail message checked by Spyware Doctor (6.0.0.386) > Database version: 5.13700 > http://www.pctools.com/en/spyware-doctor-antivirus/ > > > > > > E-mail message checked by Spyware Doctor (6.0.0.386) > Database version: 5.13700 > http://www.pctools.com/en/spyware-doctor-antivirus/ > > _______________________________________________ > 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.